Flame-retardant charcoal layer multi-source test data fusion determination method

Abstract

This invention discloses a multi-source test data fusion and judgment method for flame-retardant char layer, relating to the field of flame-retardant material testing technology. Instead of using the residual char area, morphology, or amount after combustion as a single criterion for judging the effectiveness of the flame-retardant char layer, it determines the original fire zone location based on the image of the fire-exposed surface before combustion, determines the heat release rate threshold window based on the heat release rate curve data, and combines the exposure event results from the combustion process video data and the substrate pyrolysis damage state of the corresponding cross-sectional area in the post-combustion cross-sectional image data to form the exposure heat release time correspondence result and the location damage confirmation result. Therefore, for cases where the test sample still has a char layer after combustion, but within the heat release rate threshold window result there has been an opening in the char layer, exposure of the substrate, or interruption of coverage leading to location damage confirmation, a judgment result indicating insufficient continuous protection of the flame-retardant char layer is generated.

Description

Technical Field

[0001] This invention relates to the field of flame retardant material testing technology, specifically a method for determining the multi-source test data fusion of flame retardant char layers. Background Technology

[0002] Flame-retardant materials are widely used in building decoration, transportation, electronics, wood products and polymer products. The evaluation of their combustion performance usually requires a comprehensive judgment based on the material's combustion behavior after being exposed to fire, changes in heat release, mass loss and residual state after combustion. Among these factors, the char layer formed during combustion has a significant impact on blocking heat, oxygen and combustible pyrolysis products. Therefore, multi-source test data analysis focusing on the char layer formation process and protective effect is an important research direction in the performance evaluation of flame-retardant materials.

[0003] Currently, the evaluation of flame-retardant char layers often focuses on outcome indicators such as whether there is residual char after combustion, whether the residual char area is large, whether the residual char morphology is continuous, whether the residual char rate is increased, and whether the heat release rate is reduced. However, these indicators reflect the residual state or overall combustion performance after combustion, and cannot directly indicate whether the char layer has been covering the original fire-affected area during key stages such as rapid increase in heat release and significant acceleration of mass loss. Therefore, it is possible that the residual char morphology is relatively intact after combustion, while the char layer has cracked, exposed the substrate, curled, or failed to recover in time during the combustion process. Summary of the Invention

[0004] This invention provides a method for fusing and determining multi-source test data of flame-retardant charcoal layers, which solves the problems mentioned in the background art.

[0005] A method for fusing and determining multi-source test data of flame-retardant charcoal layers includes the following steps: S1. Acquire images of the sample before combustion, video data of the combustion process, heat release rate curve data, and cross-sectional image data after combustion. S2. Obtain the original fire zone location result based on the image of the fire-exposed surface before combustion, and obtain the heat release rate threshold window result or the non-entry window mark result based on the heat release rate curve data, the preset initial heat release rate value and the preset final heat release rate value. The preset initial heat release rate value is lower than the preset final heat release rate value. S3. When obtaining the heat release rate threshold window result, the original fire zone location result and the heat release rate threshold window result are used as the identification range. In the combustion process video data, the exposed event results that appear or continue to the heat release rate threshold window result are identified. The exposed event results include at least the time of the exposed event and the location of the exposed event. S4. When the heat release rate threshold window result is obtained and the exposure event result is identified, the ignition time of the sample to be tested is used as a unified time reference. The exposure event result is matched with the heat release rate threshold window result in time to obtain the exposure heat release time correspondence result. S5. Determine the corresponding cross-sectional area in the post-combustion cross-sectional image data based on the location of the exposed event, and obtain the location damage confirmation result based on the substrate pyrolysis damage state of the corresponding cross-sectional area; when both the exposed heat release time corresponding result and the location damage confirmation result are generated, generate the determination result of insufficient continuous protection of the flame-retardant char layer; when the result of not entering the window has been generated, the result of exposed heat release time corresponding result has not been generated, or the location damage confirmation result has not been generated, generate the result of undeterminable continuous protection state of the flame-retardant char layer.

[0006] Preferably, step S1 includes: S11. Before conducting the combustion test on the sample to be tested, an image of the fire-exposed surface of the sample to be tested is acquired to obtain an image of the fire-exposed surface before combustion. S12. During the combustion test of the sample to be tested, video data of the combustion process and heat release rate curve data are collected simultaneously. After the combustion of the sample to be tested is completed, cross-sectional images of the corresponding positions of the fire-affected areas of the sample to be tested are collected to obtain cross-sectional image data after combustion. S13. Using the ignition time of the sample to be tested as a unified time reference, the video frame time in the combustion process video data and the sampling time in the heat release rate curve data are all mapped to the unified time reference.

[0007] Preferably, step S2 includes: S21. Determine the fire-receiving boundary corresponding to the conical calorimetric heating area, the flame contact area, or the preset fire-receiving area in the fire-receiving surface image before combustion. S22. The fire-affected boundary and the fire-affected area enclosed by the fire-affected boundary are determined as the original fire-affected area positioning result.

[0008] Preferably, step S2 further includes: S23. Find the sampling time when the preset initial heat release rate value is first reached in the heat release rate curve data, and determine the sampling time when the preset initial heat release rate value is first reached as the window start sampling time. S24. Using the window start sampling time as the search starting point, find the sampling time in the heat release rate curve data that first reaches the preset end heat release rate value, and determine the sampling time that first reaches the preset end heat release rate value as the window end sampling time. S25. When the window start sampling time and window end sampling time are found, the time range between the window start sampling time and the window end sampling time is determined as the heat release rate threshold window result; when the window start sampling time or window end sampling time is not found, a result indicating that the window has not been entered is generated.

[0009] Preferably, step S3 includes: S31. Based on the original fire zone location results, determine the video recognition area in the combustion process video data, and based on the heat release rate threshold window results, determine the video recognition time period in the combustion process video data. S32. Identify carbon layer opening events, substrate exposure events, carbon layer curling away events, carbon layer collapse events, or carbon layer coverage interruption events within the video recognition area and the video recognition time period, and determine the identified carbon layer opening events, substrate exposure events, carbon layer curling away events, carbon layer collapse events, or carbon layer coverage interruption events as exposure events. S33. Determine the start time and location of the exposure event based on the video data of the combustion process; when the exposure event first appears within the video recognition time period, determine the time corresponding to the first video frame in which it appears as the start time of the exposure event; when the first video frame in the video recognition time period already contains an exposure state, search backwards along time for video frames at the same location where the charcoal layer coverage state changes to an exposure state, and determine the time corresponding to that video frame as the start time of the exposure event; determine the start time of the exposure event as the exposure event occurrence time, determine the location of the exposure event in the area corresponding to the original fire zone location result as the exposure event occurrence location, and form the exposure event result from the exposure event occurrence time and the exposure event occurrence location.

[0010] Preferably, step S3 further includes: S34. Locate the moment when the exposed event disappears in the video data of the combustion process; S35. When the moment when the exposure event disappears is found, the time period from the time the exposure event occurs to the time when the exposure event disappears is determined as the exposure event's continuous state. S36. When the moment when the exposure event disappears is not found, the time period from the time the exposure event occurs to the time when the combustion ends is determined as the exposure event persistence state, and the exposure event persistence state is written into the exposure event result.

[0011] Preferably, step S4 includes: S41. Based on the unified time reference, determine whether the occurrence time of the exposure event in the exposure event results is within the heat release rate threshold window results; S42. When the time of the exposure event is within the heat release rate threshold window, generate the corresponding result for the heat release time of the exposure. S43. When the exposure event occurs earlier than the window start sampling time, determine whether the exposure event continues until the window start sampling time, and generate the corresponding result of the exposure heat release time when the exposure event continues until the window start sampling time.

[0012] Preferably, step S5 includes: S51. Based on the original fire zone location results and the cross-sectional acquisition locations of the post-combustion cross-sectional image data, establish location correspondence results; S52. Based on the location correspondence results, the location of the exposed event in the exposed event results is mapped to the cross-sectional image data after combustion, and the cross-sectional area in the cross-sectional image data corresponding to the location of the exposed event is determined as the corresponding cross-sectional area. S53. Select the cross-sectional area corresponding to the location where no exposure event occurred in the post-combustion cross-sectional image data, or select the cross-sectional area adjacent to the corresponding cross-sectional area, as the reference cross-sectional area; when a comparable reference cross-sectional area cannot be determined, the generated reference cross-sectional area is insufficient.

[0013] Preferably, when the ungenerated reference section area is insufficient, step S5 further includes: S54. Along the thickness direction from the fire-exposed surface to the unfired surface, obtain the unpyrolyzed substrate retention thickness at the corresponding position within the corresponding cross-sectional area. S55. Along the thickness direction from the fire-exposed surface to the unfired surface, obtain the thickness of the unpyrolyzed substrate at the reference position corresponding to the reference cross-section area. S56. When the thickness of the non-pyrolytic substrate at the corresponding position is lower than that at the reference position, and the thickness difference between the non-pyrolytic substrate at the corresponding position and the non-pyrolytic substrate at the reference position is greater than a preset thickness difference threshold, a position damage confirmation result is generated; when no position damage confirmation result is generated, the damage closure condition is insufficient.

[0014] Preferably, step S5 further includes: S57. Determine whether the result corresponding to the exposure heat release time has been generated, and determine whether the location damage confirmation result has been generated; S58. When the results corresponding to the exposed heat release time and the location damage confirmation results have been generated, the flame-retardant char layer of the sample to be tested is determined to be in the heat release rate threshold window result as not providing continuous protection to the area corresponding to the original fire zone location result, and a judgment result of insufficient continuous protection of the flame-retardant char layer is generated. When the result of not entering the window has been generated, the result corresponding to the exposed heat release time has not been generated, the result of location damage confirmation has not been generated, the reference section area is insufficient, or the damage closure condition is insufficient, the result of the continuous protection status of the flame-retardant carbon layer is not determined.

[0015] This invention provides a method for fusing and judging multi-source test data of flame-retardant charcoal layers, which has the following beneficial effects: 1. By jointly judging the char layer exposure during combustion, the heat release rate threshold window result, and the pyrolysis damage of the substrate at the corresponding location after combustion, the effectiveness evaluation of the flame-retardant char layer is no longer limited to the appearance and amount of residual char after combustion. This avoids misjudging char layers that remain after combustion but have experienced openings, substrate exposure, or coverage interruptions within the heat release rate threshold window as continuously effective char layers, thereby improving the accuracy and verifiability of the evaluation of the continuous protection status of the flame-retardant char layer. Attached Figure Description

[0016] Figure 1 A schematic diagram of the process for determining the multi-source test data fusion of flame-retardant char layer; Figure 2 This is a schematic diagram illustrating the logic for determining the fusion of exposure events and co-located injuries. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] Example 1 This embodiment can be applied to evaluate the char layer protection effect of flame-retardant materials such as flame-retardant wood panels for building decoration, flame-retardant composite panels for transportation interiors, flame-retardant polymer materials for electronic and electrical appliance casings, and substrates coated with intumescent flame-retardant coatings. In multiple application scenarios, wood panels coated with intumescent flame-retardant coatings are selected as the test sample for illustration. During the cone calorimetric combustion test, a flame-retardant char layer forms on the fire-exposed surface of the test sample. During the combustion process, the opening of the char layer, exposure of the substrate, curling and separation of the char layer, collapse of the char layer, or interruption of the char layer coverage are captured by video. The heat release rate threshold window result is obtained through the heat release rate curve, and the cross-sectional image corresponding to the fire-exposed area is obtained after the combustion ends, so as to determine whether the flame-retardant char layer provides continuous protection to the area corresponding to the original fire-exposed area within the heat release rate threshold window result. It should be noted that: when using wood-based panels as an example, the pyrolysis damage state of the substrate includes carbonization, pyrolysis discoloration, and retention of the non-pyrolysis substrate; when the sample to be tested is a flame-retardant polymer material, a flame-retardant composite panel, or an electronic appliance casing material, the pyrolysis damage state of the substrate corresponds to matrix melting, thermal degradation discoloration, thermal damage to the resin matrix, exposure of the reinforcing layer, retention of the non-thermally degraded layer, or retention of the non-thermally damaged substrate layer.

[0019] This invention provides a method for fusing and determining multi-source test data of flame-retardant charcoal layers. Please refer to [link / reference]. Figure 1 This includes the following steps: S1. Acquire images of the sample before combustion, video data of the combustion process, heat release rate curve data, and cross-sectional image data after combustion. S2. Obtain the original fire zone location result based on the image of the fire-exposed surface before combustion, and obtain the heat release rate threshold window result or the non-entry window mark result based on the heat release rate curve data, the preset initial heat release rate value and the preset final heat release rate value. The preset initial heat release rate value is lower than the preset final heat release rate value. S3. When obtaining the heat release rate threshold window result, the original fire zone location result and the heat release rate threshold window result are used as the identification range. In the combustion process video data, the exposed event results that appear or continue to the heat release rate threshold window result are identified. The exposed event results include at least the time of the exposed event and the location of the exposed event. S4. When the heat release rate threshold window result is obtained and the exposure event result is identified, the ignition time of the sample to be tested is used as a unified time reference. The exposure event result is matched with the heat release rate threshold window result in time to obtain the exposure heat release time correspondence result. S5. Determine the corresponding cross-sectional area in the post-combustion cross-sectional image data based on the location of the exposed event, and obtain the location damage confirmation result based on the substrate pyrolysis damage state of the corresponding cross-sectional area; when both the exposed heat release time corresponding result and the location damage confirmation result are generated, generate the determination result of insufficient continuous protection of the flame-retardant char layer; when the result of not entering the window has been generated, the result of exposed heat release time corresponding result has not been generated, or the location damage confirmation result has not been generated, generate the result of undeterminable continuous protection state of the flame-retardant char layer.

[0020] In this embodiment, by jointly judging the char layer exposure during combustion, the heat release rate threshold window result, and the pyrolysis damage of the substrate at the corresponding location after combustion, the effectiveness evaluation of the flame-retardant char layer is no longer limited to the appearance and amount of residual char after combustion. This avoids misjudging char layers that remain after combustion but have experienced openings, substrate exposure, or coverage interruptions within the heat release rate threshold window as continuously effective char layers, thereby improving the accuracy and verifiability of the evaluation of the continuous protection status of the flame-retardant char layer.

[0021] Example 2 Specifically: Step S1 includes: S11. Before conducting the combustion test on the sample to be tested, an image of the fire-exposed surface of the sample to be tested is acquired to obtain an image of the fire-exposed surface before combustion. Specifically: Based on the application scenario in Example 1, the sample to be tested is a wood board coated with an intumescent flame-retardant coating. Before the combustion test, the sample to be tested is fixed in the placement direction during the combustion test, so that the fire-exposed surface of the sample is facing the image acquisition device, and the outer contour of the fire-exposed surface of the sample, the opening boundary of the sample clamp, or the boundary of the preset fire-exposed area are located in the same image, thereby acquiring the image of the fire-exposed surface before combustion.

[0022] S12. During the combustion test of the sample to be tested, video data of the combustion process and heat release rate curve data are collected simultaneously. After the combustion of the sample to be tested is completed, cross-sectional images of the corresponding positions of the fire-affected areas of the sample to be tested are collected to obtain cross-sectional image data after combustion. Specifically: During the cone calorimetric combustion test of the sample to be tested, the combustion process of the sample's exposed surface is continuously captured by a camera device to obtain video data of the combustion process. At the same time, the heat release rate of the sample during the combustion process is recorded by the cone calorimetric testing equipment to obtain heat release rate curve data. After the sample has finished burning and cooled, a cross-section is cut according to the center line of the exposed area, the preset partition cross-section line, or the preset cutting line in the exposed area and the cross-sectional image is acquired. Alternatively, a cross-section passing through the location of the exposure event can be supplemented according to the location of the exposure event, thereby obtaining the cross-sectional image data after combustion. It should be noted that the cross-sectional image data after combustion is used to observe the pyrolysis damage state of the substrate in the direction from the fire-exposed surface to the unfired surface. The cross-sectional image should include the fire-exposed surface, the unfired surface, the carbonized area, the pyrolysis-damaged area, and the unpyrolyzed substrate area, so as to facilitate the subsequent determination of the corresponding cross-sectional area, the reference cross-sectional area, and the remaining thickness of the unpyrolyzed substrate.

[0023] S13. Using the ignition time of the sample to be tested as a unified time reference, the video frame time in the combustion process video data and the sampling time in the heat release rate curve data are all mapped to the unified time reference. Specifically: the moment when the sample under test is ignited is taken as the zero moment of the unified time reference, and the time of each video frame in the combustion process video data and each sampling moment in the heat release rate curve data are converted to the time relative to the zero moment; if the original time starting points of the combustion process video data and the heat release rate curve data are different, the video frame time corresponding to the ignition moment and the equipment acquisition time are used as the correction reference for conversion respectively.

[0024] It should be noted that the ignition time is preferentially adopted as the moment when the flame first contacts the flame-exposed surface of the sample in the combustion process video data and remains in contact until the next video frame, and the ignition time recorded by the cone calorimeter is used as the verification time; when there is a time difference between the two, the ignition time determined in the combustion process video data is used as the unified time reference.

[0025] Step S2 includes: S21. Determine the fire-receiving boundary corresponding to the conical calorimetric heating area, the flame contact area, or the preset fire-receiving area in the fire-receiving surface image before combustion. Specifically: In the image of the fire-exposed surface before combustion, the fire-exposed boundary is determined by the boundary of the sample fixture opening, the projection boundary of the cone-shaped calorimetric radiation area on the fire-exposed surface of the sample, the boundary of the area directly in contact with the flame, or the boundary of the fire-exposed area determined in advance before the test; when the edge of the sample fixture opening is not easily identifiable, the fire-exposed boundary is determined by the outer contour of the sample, the size of the sample fixture opening, and the placement position of the sample in the sample fixture.

[0026] S22. The fire-affected boundary and the fire-affected area enclosed by the fire-affected boundary are determined as the original fire-affected area positioning result; Specifically: After determining the fire-affected boundary, the fire-affected boundary itself and the area inside the fire-affected boundary are used together as the original fire-affected area positioning result. Image coordinates are established in the fire-affected surface image before combustion to record the location range of the fire-affected boundary and the fire-affected area, so that the original fire-affected area positioning result can be mapped to the subsequent combustion process video data and post-combustion cross-sectional image data. It should be noted that the original fire zone location result is the fire zone determined before the start of combustion, not the residual char area after the end of combustion. Therefore, even if the char layer expands, cracks, curls, collapses, or its coverage is interrupted, the area corresponding to the original fire zone location result is still used as the spatial basis for judging whether the flame-retardant char layer continues to cover the original fire zone.

[0027] Step S2 further includes: S23. Find the sampling time when the preset initial heat release rate value is first reached in the heat release rate curve data, and determine the sampling time when the preset initial heat release rate value is first reached as the window start sampling time. Specifically: The preset initial heat release rate value is used to determine the starting point for the sample to enter the heat release stage of interest in this evaluation. The preset initial heat release rate value is determined based on the pre-experimental data of similar samples, the requirements of the testing standard, or the heat release rate curve of the same batch of samples, and is kept consistent in the same batch of samples. During data processing: Starting from time zero corresponding to the unified time base, the sampling point in the heat release rate curve data is searched point by point according to the sampling order. The time corresponding to the first sampling point that reaches the preset initial heat release rate value is determined as the window start sampling time. When there is a single point jump in the heat release rate curve data, a smooth curve exported by the cone calorimeter is used or the heat release rate curve data is smoothed before searching for the window start sampling time. When the heat release rate curve data never reaches the preset initial heat release rate value, the window start sampling time is not generated.

[0028] S24. Using the window start sampling time as the search starting point, find the sampling time in the heat release rate curve data that first reaches the preset end heat release rate value, and determine the sampling time that first reaches the preset end heat release rate value as the window end sampling time. Specifically: The preset end heat release rate value is used to determine the endpoint of the heat release rate threshold window result. The preset end heat release rate value is higher than the preset start heat release rate value, and is determined according to the material type of the sample to be tested, the flame retardant system, the pre-experimental data of similar samples, and the purpose of the test. During data processing: Starting from the sampling point corresponding to the window's initial sampling time, the sampling order in the heat release rate curve data is searched backwards, and the time corresponding to the first sampling point that reaches the preset end heat release rate value is determined as the window's end sampling time; when the heat release rate curve data has multiple peaks, the sampling time that first reaches the preset end heat release rate value after the window's initial sampling time is taken as the window's end sampling time; when the heat release rate curve data never reaches the preset end heat release rate value after the window's initial sampling time, no window's end sampling time is generated.

[0029] For example, if the heat release rate of the same batch of test samples fluctuates at a low level of no more than 20 kW / m² during the initial ignition stage, and the heat release rate begins to exceed 50 kW / m² after entering the stable combustion stage, the preset initial heat release rate value can be set to 50 kW / m²; if the preset initial heat release rate value is 50 kW / m² and similar samples can reach more than 150 kW / m², the preset final heat release rate value can be set to 150 kW / m². The above values ​​are used to define the time period when the heat release rate changes from a lower level to a higher level, and should be kept consistent in the same batch of test samples.

[0030] In the specific tests, the heat release rate curve data were recorded using a cone calorimeter with a sampling interval of 1 second, and the ignition time of the sample was used as a unified time reference. The heat release rate curve data of each sample was searched point-by-point according to the preset initial heat release rate value and the preset final heat release rate value, resulting in the following heat release rate threshold window results:

[0031] Table 1; Test results of heat release rate threshold window FR-WD-260318-01 Flame-retardant wood boards 195 410 Generate heat release rate threshold window results FR-WD-260319-02 Flame-retardant wood boards — — Generate results for marking items not entered into the window. FR-PP-260323-01 Flame-retardant polypropylene sheets 118 225 Generate heat release rate threshold window results FR-PP-260324-02 Flame-retardant polypropylene sheets 120 238 Generate heat release rate threshold window results FR-CMP-260326-01 Flame-retardant fiber-reinforced composite board 150 305 Generate heat release rate threshold window results FR-CMP-260331-02 Flame-retardant fiber-reinforced composite board 132 280 Generate heat release rate threshold window results FR-SH-260402-01 Flame-retardant PC / ABS shell sheet 75 160 Generate heat release rate threshold window results FR-WD-260407-03 Flame-retardant wood boards 240 530 Generate heat release rate threshold window results FR-EP-260409-01 Flame-retardant epoxy composite materials 190 360 Generate heat release rate threshold window results FR-PU-260414-01 Flame-retardant polyurethane materials 60 110 Generate heat release rate threshold window results

[0032] The window start sampling time and window end sampling time in Table 1 were obtained by searching the heat release rate curve point by point according to the preset start heat release rate value and preset end heat release rate value within the same test group; among them, the preset start heat release rate value and preset end heat release rate value are consistent within the same material test group.

[0033] The window for FR-WD-260318-01 starts at 195s and ends at 410s. Subsequently, only exposure phenomena that occur or continue within the time range of 195s to 410s will be used as the objects for judging the exposure heat release time.

[0034] FR-WD-260319-02 did not meet the conditions for forming a heat release rate threshold window result, therefore a result marked as not entering the window was generated, and the judgment corresponding to the exposed event within the window was not forcibly entered.

[0035] S25. When the start sampling time and end sampling time of the window are found, the time range between the start sampling time and the end sampling time of the window is determined as the heat release rate threshold window result; when the start sampling time or end sampling time of the window is not found, a "not entered window" mark result is generated. Specifically: The heat release rate threshold window result is the time range from the start of the window sampling time to the end of the window sampling time. Video frame times and heat release rate sampling times within this time range are considered to fall within the heat release rate threshold window result. When no window start sampling time or window end sampling time is generated, it means that the sample under test has not entered the heat release rate threshold window result set in this time, and a "not entered window" mark result is generated.

[0036] It should be noted that the heat release rate threshold window result is used to limit the heat release evaluation stage of interest in this evaluation, and is not equivalent to the entire high heat release period of the entire combustion process. When the purpose of the test is to evaluate the char layer protection status near the high heat release plateau or peak, the preset initial heat release rate value and preset final heat release rate value can be reset according to the pre-experiment curve of the same batch of samples and then reprocessed.

[0037] In this embodiment, through the processing of Example 2, the images of the fire-exposed surface before combustion, the video data of the combustion process, the heat release rate curve data, and the cross-sectional image data after combustion are formed under a unified time reference and the original fire-exposed zone positioning results to form a time and space correspondence basis. The heat release rate threshold window results are obtained by preset initial heat release rate value, preset end heat release rate value, window start sampling time, and window end sampling time, thereby providing a stable data basis for subsequent exposure event results, exposure heat release time correspondence results, and location damage confirmation results.

[0038] Example 3 Specifically: Step S3 includes: S31. Based on the original fire zone location results, determine the video recognition area in the combustion process video data, and based on the heat release rate threshold window results, determine the video recognition time period in the combustion process video data. Specifically: Based on the application scenario in Example 1, the sample to be tested is a wood board coated with an intumescent flame-retardant coating. After determining the original fire zone location result, the original fire zone location result is mapped to each video frame of the combustion process video data, and the area in each video frame corresponding to the original fire zone location result is used as the video recognition area. If the image size of the fire-affected surface before combustion and the video data of the combustion process are different, the scaling is performed according to the position ratio of the inner edge of the sample fixture, the outer contour of the sample to be tested, or the fire boundary in the two types of images.

[0039] Specifically, the heat release rate threshold window result includes the window start sampling time and the window end sampling time. Video frames in the combustion process video data whose time falls between the window start sampling time and the window end sampling time are determined as the video recognition time period. For example, if the window start sampling time is 80s and the window end sampling time is 140s, then the video frames in the combustion process video data between 80s and 140s are taken as the video recognition time period.

[0040] It should be noted that: the video recognition time period is used to determine whether the exposure event occurs within the heat release rate threshold window result; when the exposure state already exists in the first video frame of the video recognition time period, the combustion process video data before the window start sampling time at the same position is reviewed to determine the occurrence time and duration of the exposure event. This review process does not change the range of the video recognition time period.

[0041] S32. Identify carbon layer opening events, substrate exposure events, carbon layer curling away events, carbon layer collapse events, or carbon layer coverage interruption events within the video recognition area and the video recognition time period, and determine the identified carbon layer opening events, substrate exposure events, carbon layer curling away events, carbon layer collapse events, or carbon layer coverage interruption events as exposure events. Specifically: The carbon layer coverage status of the sample under test on the fire-exposed surface is examined frame by frame within the video recognition area and video recognition time period. When the carbon layer shows an opening, exposed substrate, curled away from the original coverage position, or collapsed to form a coverage gap in the area corresponding to the original fire-exposed area location result, or when the same position changes from a covered state to an uncovered state in adjacent video frames, the corresponding phenomenon is identified as an exposure event.

[0042] During data processing: Exposed events can be identified by manual interpretation, image processing, or a combination of both. When manual interpretation is used, the area corresponding to the original fire zone location result is used as the observation range, and the changes in the char layer coverage state are recorded frame by frame. When image processing is used, the unburned substrate reference area and the char layer reference area are selected first, and then the area that is inconsistent with the char layer reference area and close to the unburned substrate reference area is identified in the video recognition area, or the uncovered area formed by the opening, curling, or collapse of the continuous boundary of the char layer is identified.

[0043] It should be noted that, in order to avoid the misjudgment of flame flickering, smoke obstruction, or single-frame reflection as an exposure event, an exposure event should meet the following requirements: the location falls within the area corresponding to the original fire zone location result, the same uncovered state is maintained in adjacent video frames, or there is a change from covered to uncovered state, and the location can be subsequently determined as the location of the exposure event; when there is occlusion in the video that makes it impossible to determine, the video frame is marked as an unreadable frame and is not used as the exposure event time alone.

[0044] S33. Determine the start time and location of the exposure event based on the video data of the combustion process; when the exposure event first appears within the video recognition time period, determine the time corresponding to the first video frame in which it appears as the start time of the exposure event;

[0045] Specifically: After an exposure event is identified, if the exposure event does not already exist in the first video frame of the video recognition time period, then the video frame in which the exposure event first appears within the video recognition time period is searched, and the time corresponding to that video frame is taken as the start time of the exposure event; if the exposure event already exists in the first video frame of the video recognition time period, then the combustion process video data is viewed backwards from that first video frame to find the earliest video frame in which the location of the same exposure event changes from a state of charcoal layer coverage to a state of exposure, and the time corresponding to that earliest video frame is taken as the start time of the exposure event.

[0046] It should be noted that reviewing the combustion process video data in reverse chronological order is to determine the actual occurrence time of the exposure event within the heat release rate threshold window, rather than to expand the scope of the exposure event judgment. For example, if the initial sampling time of the window is 80 seconds, and the first video frame of the video recognition time period already shows an exposed state, and looking back reveals that the same location changed from a char-covered state to an exposed state at 70 seconds, then 70 seconds is determined as the starting time of the exposure event.

[0047] When an exposed state already exists in the first video frame of the video recognition time period, the video frames at the same location that changed from a state covered by a carbon layer to an exposed state are searched backwards along the time, and the time corresponding to the video frame is determined as the start time of the exposure event; the start time of the exposure event is determined as the exposure event occurrence time, and the location of the exposure event in the area corresponding to the original fire zone location result is determined as the exposure event occurrence location. The exposure event result is formed by the exposure event occurrence time and the exposure event occurrence location.

[0048] Specifically: the time of exposure events is represented by a unified time reference, and the location of exposure events is represented by the fire-affected area partition, image coordinates, or position relative to the fire boundary; when there are multiple exposure events within the same video recognition time period, the exposure event time and location corresponding to each exposure event are recorded separately, thus forming multiple exposure event results.

[0049] Step S3 further includes: S34. Locate the moment when the exposed event disappears in the video data of the combustion process; Specifically: After determining the time of the exposure event, starting from the video frame corresponding to the time of the exposure event, continue to view the video data of the combustion process in chronological order to determine whether the same exposure event location is covered by the char layer again, or whether the original opening, exposed substrate, curled away, collapsed, or interrupted coverage state no longer exists; the time when the exposure event disappears is the time corresponding to the video frame where the same exposure event location changes from an exposed state to a non-exposed state.

[0050] S35. When the moment when the exposure event disappears is found, the time period from the time the exposure event occurs to the time when the exposure event disappears is determined as the exposure event's continuous state. Specifically: When the moment when the exposure event disappears is found in the video data of the combustion process, the time when the exposure event occurs is taken as the starting point of the continuous state, and the time when the exposure event disappears is taken as the ending point of the continuous state. The time period between the starting point and the ending point is determined as the continuous state of the exposure event. For example, if the exposure event occurs at 92s and disappears at 115s, then the time period between 92s and 115s is determined as the continuous state of the exposure event.

[0051] S36. When the moment when the exposure event disappears is not found, the time period from the time the exposure event occurs to the time when the combustion ends is determined as the exposure event persistence state, and the exposure event persistence state is written into the exposure event result. Specifically: If, from the video frame corresponding to the time of the exposure event until the end of the video data of the combustion process, no carbon layer is found to be re-covered at the same location of the exposure event, or no opening, substrate exposure, curling away, collapse, or disappearance of the coverage interruption state is found, the time period from the time of the exposure event to the end of the combustion is defined as the exposure event duration state.

[0052] It should be noted that: the combustion end time is preferentially adopted as the moment when the flame is extinguished and the test sample no longer shows visible combustion in the combustion process video data, and the test end time recorded by the cone calorimeter is used as the verification time; when the difference between the two exceeds the larger of the time interval of one video frame of the combustion process video data and one sampling period of the heat release rate curve data, the combustion end time determined in the combustion process video data is taken as the end point of the exposure event duration.

[0053] Step S4 includes: S41. Based on the unified time reference, determine whether the occurrence time of the exposure event in the exposure event results is within the heat release rate threshold window results; Specifically: The occurrence time of the exposure event is compared with the window start sampling time and window end sampling time in the heat release rate threshold window result; when the occurrence time of the exposure event is not earlier than the window start sampling time and not later than the window end sampling time, it is determined that the occurrence time of the exposure event is within the heat release rate threshold window result.

[0054] S42. When the time of the exposure event is within the heat release rate threshold window, generate the corresponding result for the heat release time of the exposure. Specifically: When the time of the exposure event falls within the heat release rate threshold window, record the time of the exposure event, the location of the exposure event, the start sampling time of the window, and the end sampling time of the window, and generate the corresponding result of the heat release time of the exposure. For example: if the start sampling time of the window is 80s, the end sampling time of the window is 140s, and the time of the exposure event is 92s, then the corresponding result of the heat release time of the exposure will be generated.

[0055] S43. When the exposure event occurs earlier than the window start sampling time, determine whether the exposure event continues to the window start sampling time, and generate the corresponding result of the exposure heat release time when the exposure event continues to the window start sampling time. Specifically: When the exposure event occurs earlier than the window's initial sampling time, the duration of the exposure event is read, and it is determined whether the duration of the exposure event covers the window's initial sampling time. If the duration of the exposure event covers the window's initial sampling time, it means that although the exposure event occurs earlier than the heat release rate threshold window result, it still exists at the start of the heat release rate threshold window result. Therefore, a result corresponding to the exposure heat release time is generated. For example, if the window's initial sampling time is 80s, the exposure event occurs at 70s, and the duration of the exposure event is from 70s to 100s, then a result corresponding to the exposure heat release time is generated. If the duration of the exposure event is from 70s to 75s, then no result corresponding to the exposure heat release time is generated.

[0056] In the specific tests, the combustion process video data used the ignition time as a unified time reference. Video segments that were within or extended into the heat release rate threshold window were identified frame by frame. False judgments caused by flame flickering, smoke obstruction, reflection, or single-frame anomalies were eliminated by verifying adjacent frames. The following exposure event results were obtained, as shown in Table 2.

[0057] Table 2: Results of Nudity Event Identification and Time Correspondence FR-WD-260318-01 195-410 268s / 6700th frame Carbon layer opening event X42-Y27 yes FR-WD-260319-02 Not entered window — Unidentified — no FR-PP-260323-01 118-225 142s / 3550th frame Substrate exposure incident X36-Y18 yes FR-PP-260324-02 120-238 — Unidentified — no FR-CMP-260326-01 150-305 — Suspected carbon layer coverage interruption, verification unreadable. — no FR-CMP-260331-02 132-280 197s / Frame 4925 Carbon layer collapse event X51-Y22 yes FR-SH-260402-01 75-160 88s / 2200th frame Carbon layer coverage interruption event X29-Y16 yes FR-WD-260407-03 240-530 336s / 8400th frame Carbon layer curling and leaving event X47-Y31 yes FR-EP-260409-01 190-360 175s / Frame 4375 Carbon layer opening event X33-Y21 yes FR-PU-260414-01 60-110 93s / Frame 2325 Substrate exposure incident X24-Y19 yes

[0058] Among them, FR-WD-260318-01 has a carbon layer opening event at 268s / 6700th frame. This time is within the heat release rate threshold window result of 195s to 410s, and the location of the event is within the area corresponding to the original fire zone location result. Therefore, the result corresponding to the exposed heat release time is generated.

[0059] The carbon layer opening event of FR-EP-260409-01 occurred at 175s, earlier than the window start sampling time of 190s. However, the exposure event continued after the window start sampling time, thus generating the corresponding result for the exposure heat release time.

[0060] Although FR-CMP-260326-01 shows a suspected carbon layer coverage interruption at 181s / frame 4525, due to smoke obscuring the data and the inability to confirm it in adjacent frames, this phenomenon is only recorded as a suspected event and does not form a formal exposure event result, nor does it generate a result corresponding to the exposure heat release time.

[0061] In this embodiment, through the processing of Example 3, the exposure event result is not directly obtained from any char layer change during the combustion process. Instead, it is formed by locating and timing char layer opening events, substrate exposure events, char layer curling and leaving events, char layer collapse events, or char layer coverage interruption events within the area defined by the original fire zone location result and the time period defined by the heat release rate threshold window result. The exposure event persistence status is used to determine whether the exposure phenomenon that occurred earlier than the window start sampling time continues to the heat release rate threshold window result, thereby avoiding the omission of early exposure events that continue to the heat release rate threshold window result.

[0062] Example 4 Please see Figure 2 Specifically, step S5 includes: S51. Based on the original fire zone location results and the cross-sectional acquisition locations of the post-combustion cross-sectional image data, establish location correspondence results; Specifically: Based on the application scenario in Example 1, the sample to be tested is a wood board coated with an intumescent flame-retardant coating. After the combustion ends and the cross-sectional image data after combustion is obtained, the original fire-affected zone location determined before combustion is matched with the actual cross-sectional acquisition location after combustion, so that the location of the exposed event recorded in the video data of the combustion process can be matched with the specific cross-sectional area in the cross-sectional image data after combustion.

[0063] During data processing: using the unburned edge of the sample under test, the inner edge of the sample holder, the fire-exposed boundary, or the preset cutting line as common references, record the position of the original fire-exposed zone relative to the edge of the sample under test or the inner edge of the sample holder, and record the position of the cross-sectional cutting line after combustion relative to the same reference. After matching the two, establish the position correspondence result. When the sample under test expands, contracts, warps, has edge ablation, or has char layer detachment after combustion, the unburned edge of the sample under test, the edge of the unexposed surface, the indentation of the inner edge of the sample holder, or the preset cutting line are used as position references.

[0064] It should be noted that when there is a deviation between the location of the exposed event and the actual cross-sectional cutting line, the local area near the measurement line in the cross-sectional image is used as the corresponding cross-sectional area; when the deviation causes the location of the exposed event to not fall into any acquired cross-sectional image, a cross-sectional image passing through the location of the exposed event is supplemented, or no location damage confirmation result is generated for the exposed event.

[0065] S52. Based on the location correspondence results, the location of the exposed event in the exposed event results is mapped to the cross-sectional image data after combustion, and the cross-sectional area in the cross-sectional image data corresponding to the location of the exposed event is determined as the corresponding cross-sectional area.

[0066] Specifically: After establishing the location correspondence results, read the location of the exposed event in the exposed event results, and find the cross-sectional location corresponding to the location of the exposed event in the post-combustion cross-sectional image data. The local cross-sectional area formed by extending the cross-sectional location along the fire-exposed surface toward the unfired surface is determined as the corresponding cross-sectional area.

[0067] When determining the corresponding cross-sectional area, first mark the fire-exposed surface and the unexposed surface in the post-combustion cross-sectional image data. Then, determine one or a set of measurement lines along the thickness direction at the lateral position corresponding to the location of the exposure event, and take the local cross-sectional area near the measurement line as the corresponding cross-sectional area. When the post-combustion cross-sectional image data is tilted, first perform size calibration and orientation correction on the image according to the scale, the boundary of the fire-exposed surface and the boundary of the unexposed surface, so that the thickness measurement direction is perpendicular to the fire-exposed surface.

[0068] S53. Select the cross-sectional area corresponding to the location where no exposure event occurred in the post-combustion cross-sectional image data, or select the cross-sectional area adjacent to the corresponding cross-sectional area, as the reference cross-sectional area; when a comparable reference cross-sectional area cannot be determined, the generated reference cross-sectional area is insufficient. Specifically: The reference section area is used to compare the damage status with the corresponding section area. Priority is given to selecting the section area corresponding to the location where no exposed event was recorded in the original fire zone location results. When the location where no exposed event occurred cannot be found directly, the section area adjacent to the corresponding section area and not recorded as the location of the exposed event in the combustion process video data is selected as the reference section area.

[0069] It should be noted that: the reference section area should be in the same post-combustion cross-sectional image data as the corresponding section area, or in the post-combustion cross-sectional image data obtained under the same fire conditions and the same cross-sectional acquisition direction; when a large area of ​​the original fire zone location result has an exposure event, the adjacent area itself is in the edge heating or flame erosion position, or the reference section area has cutting defects, char layer peeling defects, or local void defects, the area will not be used as the reference section area; when a comparable reference section area cannot be determined, no position damage confirmation result will be generated, and the sample to be tested will be recorded as having insufficient reference section area.

[0070] When the ungenerated reference section area is insufficient, step S5 further includes: S54. Along the thickness direction from the fire-exposed surface to the unfired surface, obtain the unpyrolyzed substrate retention thickness at the corresponding position within the corresponding cross-sectional area. Specifically: In the corresponding cross-sectional area, first determine the positions of the fire-exposed surface and the unexposed surface, then identify the carbonized area, the pyrolysis-damaged area and the non-pyrolysis substrate area along the thickness direction from the fire-exposed surface to the unexposed surface, and measure the retained thickness of the non-pyrolysis substrate area in the thickness direction, and take this thickness as the retained thickness of the non-pyrolysis substrate at the corresponding position.

[0071] When obtaining the thickness of the unpyrolyted substrate at the corresponding location, the thickness reading line is set along the direction from the fire-exposed surface to the unfired surface, with the location of the exposed event in the post-combustion cross-sectional image data as the center. The distance between the boundary of the unpyrolyzed substrate region on the side closest to the fire-exposed surface and the unexposed surface is taken as the unpyrolyzed substrate retention thickness on this thickness reading line. To reduce single-point errors, multiple parallel thickness reading lines can be set within a preset width range on both sides of the position, and the average thickness obtained from each thickness reading line can be used as the retained thickness of the unpyrolyzed substrate at the corresponding position.

[0072] In this embodiment: the wood substrate near the unexposed surface and unaffected by heat in the same post-combustion cross-sectional image data is used as the reference area of ​​the non-pyrolytic substrate. The non-pyrolytic substrate area is a continuous area with the same color, brightness and wood texture as the non-pyrolytic substrate reference area. The carbonized area is an area that is close to black or dark brown and has lost the continuity of wood texture. The pyrolysis damaged area is an area located between the carbonized area and the non-pyrolytic substrate area, with a darker color than the non-pyrolytic substrate reference area and damaged wood texture.

[0073] In this embodiment: the wood substrate that is close to the unexposed side and not affected by heat in the same post-combustion cross-sectional image data is used as the reference area of ​​the unpyrolyzed substrate. The unpyrolyzed substrate area is a continuous area with the same color, brightness and wood texture as the reference area of ​​the unpyrolyzed substrate. The carbonized areas are nearly black or dark brown and have lost the continuity of the wood grain. The pyrolysis-damaged area is the region located between the carbonized area and the non-pyrolyzed substrate area, which is darker in color than the non-pyrolyzed substrate reference area and has damaged wood grain.

[0074] When the sample to be tested is a non-wood material, the area of ​​the bulk material that is close to the unexposed side and is not affected by heat in the same post-combustion cross-sectional image data is used as the reference area of ​​the unpyrolyzed substrate. The unpyrolyzed substrate area is the area whose body color, brightness, gloss, continuous structure, or undamaged morphology is consistent with the unpyrolyzed substrate reference area; The pyrolysis damage area is a region that exhibits at least one of the following conditions relative to the unpyrolyzed substrate reference area: discoloration, melting deformation, foaming, pores, cracks, resin matrix damage, or exposure of the reinforcing layer. The identification of the above-mentioned areas can be performed by manual interpretation, image processing, or a combination of manual interpretation and image processing.

[0075] During data processing: The dimensions of the cross-sectional image data after combustion are calibrated using the known thickness of the sample to be tested or the scale in the cross-sectional image, and the pixel distance in the image is converted into the actual thickness; when the boundary of the region in the cross-sectional image is unclear, the color and texture of the unpyrolyzed substrate reference area are used as the basis for judgment, and the boundary of the unpyrolyzed substrate region is confirmed by combining the continuous structure of the cross-section.

[0076] When the corresponding cross-sectional area cannot distinguish between the pyrolysis-damaged area and the non-pyrolysis substrate area due to cutting defects, smoke contamination, melting and mixing, reflection, or insufficient image clarity, the thickness of the non-pyrolysis substrate at the corresponding position is not forcibly obtained and is recorded as insufficient damage closure conditions; in this case, no position damage confirmation result is generated.

[0077] For example: If the total thickness of the cross section of the sample to be tested is 18mm, and in the corresponding cross section area, if the unpyrolyzed substrate area extends from 12mm from the fire-exposed surface to 18mm from the unfired surface, then the thickness of the unpyrolyzed substrate at the corresponding position is 6mm.

[0078] S55. Along the thickness direction from the fire-exposed surface to the unfired surface, obtain the thickness of the unpyrolyzed substrate at the reference position corresponding to the reference cross-section area. Specifically: In the reference section area, the same thickness direction, the same size calibration method and the same non-pyrolytic substrate area determination rules as the corresponding section area are used to identify the non-pyrolytic substrate area, and the retained thickness of the non-pyrolytic substrate area in the thickness direction is measured. This thickness is used as the retained thickness of the non-pyrolytic substrate at the reference position.

[0079] It should be noted that the thickness of the non-pyrolytic substrate at the corresponding position and the thickness of the non-pyrolytic substrate at the reference position should be obtained under the same scale, the same thickness direction and the same area judgment rules. For example, if the total thickness of the cross section of the same sample to be tested is 18 mm, and in the reference cross section area, if the non-pyrolytic substrate area extends from 9 mm away from the fire-exposed surface to 18 mm away from the unfired surface, then the thickness of the non-pyrolytic substrate at the reference position is 9 mm.

[0080] S56. When the thickness of the unpyrolyzed substrate at the corresponding position is lower than the thickness of the unpyrolyzed substrate at the reference position, and the thickness difference between the thickness of the unpyrolyzed substrate at the corresponding position and the thickness of the unpyrolyzed substrate at the reference position is greater than a preset thickness difference threshold, a position damage confirmation result is generated; when no position damage confirmation result is generated, the damage closure condition is insufficient. Specifically: the thickness difference between the thickness of the unpyrolyzed substrate at the reference position and the thickness of the unpyrolyzed substrate at the reference position is obtained by subtracting the thickness of the unpyrolyzed substrate at the reference position from the thickness of the unpyrolyzed substrate at the reference position. When the thickness of the unpyrolyzed substrate at the reference position is lower than the thickness of the unpyrolyzed substrate at the reference position, and the thickness difference is greater than a preset thickness difference threshold, it indicates that there is less unpyrolyzed substrate remaining in the post-combustion cross-sectional area corresponding to the location of the exposed event, and the difference has exceeded the measurement error range, thereby generating a location damage confirmation result.

[0081] During data processing: the preset thickness difference threshold is determined based on the image size calibration error, cross-sectional cutting error, and repeatability standard deviation, and the maximum value among the image size calibration error, cross-sectional cutting error, and repeatability standard deviation is taken; when the above error data are not obtained in advance, the preset thickness difference threshold is determined based on the thickness of the sample to be tested, the cross-sectional image resolution, and the minimum reading of the measuring tool, and is kept consistent in the same batch of samples to be tested.

[0082] For example, in a specific test, after the cross-sectional image data after combustion is calibrated by the image scale, the thickness of the unpyrolyzed substrate is obtained along the thickness direction from the fire-exposed surface to the unfired surface; the thickness of the unpyrolyzed substrate at the corresponding position is set with three parallel thickness reading lines centered on the cross-sectional area corresponding to the location of the exposure event and the average value is taken; the thickness of the unpyrolyzed substrate at the reference position is selected from at least two comparable reference areas in the same cross-sectional image where no exposure event has occurred and the average value is taken.

[0083] When the cross-sectional boundary is unclear, there is molten mixing, cutting defects, or the image is unreadable, no location damage confirmation result is generated.

[0084] Based on the above measurement method, the following location damage confirmation results were obtained, as shown in Table 3.

[0085] Table 3: Confirmation Results of Retained Thickness and Location Damage of Unpyrolyted Substrate in the Cross-Section After Combustion FR-WD-260318-01 CS-WD01-A 5.8 10.4 4.6 1.2 yes FR-WD-260319-02 — — — — 1.2 no FR-PP-260323-01 CS-PP01-B 1.1 2.5 1.4 0.5 yes FR-PP-260324-02 — — — — 0.5 no FR-CMP-260326-01 — — — — 0.8 no FR-CMP-260331-02 CS-CMP02-C Unable to distinguish 3.2 — 0.8 no FR-SH-260402-01 CS-SH01-A 0.7 2.1 1.4 0.4 yes FR-WD-260407-03 CS-WD03-B 6.3 12 5.7 1.2 yes FR-EP-260409-01 CS-EP01-A 1.6 4.1 2.5 0.8 yes FR-PU-260414-01 CS-PU01-A 5.2 5.7 0.5 1 no

[0086] Among them, the location X42-Y27 of the exposed event of FR-WD-260318-01 corresponds to the post-combustion cross-sectional area CS-WD01-A. The thickness of the non-pyrolyzed substrate at this corresponding location is 5.8 mm, and the thickness of the non-pyrolyzed substrate at the reference location is 10.4 mm. The thickness difference between the two is 4.6 mm, which is greater than the preset thickness difference threshold of 1.2 mm. Therefore, the location damage confirmation result is generated.

[0087] Although FR-PU-260414-01 identified a substrate exposure event within the heat release rate threshold window, the thickness of the non-pyrolyzed substrate at the corresponding location was 5.2 mm, and the thickness of the non-pyrolyzed substrate at the reference location was 5.7 mm. The thickness difference between the two was 0.5 mm, which did not exceed the preset thickness difference threshold of 1.0 mm. Therefore, no location damage confirmation result was generated.

[0088] Although FR-CMP-260331-02 identified a char layer collapse event within the heat release rate threshold window, the corresponding cross-sectional area after combustion exhibited boundary mixing, making it impossible to distinguish the unpyrolyzed substrate area. Therefore, no location damage confirmation result was generated.

[0089] Step S5 further includes: S57. Determine whether the result corresponding to the exposure heat release time has been generated, and determine whether the location damage confirmation result has been generated; Specifically: Read the results corresponding to the heat release time of exposure and the location damage confirmation results, and use the location and time of the exposure event as the identification criteria for the same exposure event to determine whether the same exposure event has both the results corresponding to the heat release time of exposure and the location damage confirmation results.

[0090] S58. When the results corresponding to the exposed heat release time and the location damage confirmation results have been generated, the flame-retardant char layer of the sample to be tested is determined to be in the heat release rate threshold window result as not providing continuous protection to the area corresponding to the original fire zone location result, and a judgment result of insufficient continuous protection of the flame-retardant char layer is generated. Specifically: When the same exposure event has generated a result corresponding to the exposure heat release time, and the corresponding cross-sectional area corresponding to the location of the exposure event has generated a location damage confirmation result, it indicates that the exposure event occurred within the heat release rate threshold window result or continued into the heat release rate threshold window result, and there is corresponding deeper substrate pyrolysis damage in the cross-section after combustion at the location of the exposure event, thereby generating a determination result of insufficient continuous protection of the flame retardant char layer.

[0091] It should be noted that the determination of insufficient continuous protection of the flame-retardant char layer is not based solely on the presence of residual char after combustion, nor solely on the presence of exposed events in the combustion process video data. Rather, it is determined when the time of the exposed event corresponds to the formation of the heat release rate threshold window result, and when the location of the exposed event and the corresponding cross-sectional area after combustion form damage closure.

[0092] Furthermore, by fusing the results corresponding to the exposure heat release time and the location damage confirmation results, the following judgment results were obtained, as shown in Table 4.

[0093] Table 4: Results of Multi-Source Test Data Fusion Judgment FR-WD-260318-01 yes yes Insufficient sustained protection of flame-retardant charcoal layer. FR-WD-260319-02 no no The continuous protective state of the flame-retardant charcoal layer is undetermined. FR-PP-260323-01 yes yes Insufficient sustained protection of flame-retardant charcoal layer. FR-PP-260324-02 no no The continuous protective state of the flame-retardant charcoal layer is undetermined. FR-CMP-260326-01 no no The continuous protective state of the flame-retardant charcoal layer is undetermined. FR-CMP-260331-02 yes no The continuous protective state of the flame-retardant charcoal layer is undetermined. FR-SH-260402-01 yes yes Insufficient sustained protection of flame-retardant charcoal layer. FR-WD-260407-03 yes yes Insufficient sustained protection of flame-retardant charcoal layer. FR-EP-260409-01 yes yes Insufficient sustained protection of flame-retardant charcoal layer. FR-PU-260414-01 yes no The continuous protective state of the flame-retardant charcoal layer is undetermined.

[0094] As shown in Table 4, FR-WD-260318-01, FR-PP-260323-01, FR-SH-260402-01, FR-WD-260407-03 and FR-EP-260409-01 simultaneously generated results corresponding to the exposed heat release time and location damage confirmation results, thus generating a judgment result of insufficient continuous protection of the flame-retardant char layer.

[0095] FR-WD-260319-02, FR-PP-260324-02, FR-CMP-260326-01, FR-CMP-260331-02, and FR-PU-260414-01 generated an undeterminable result for the continuous protection status of the flame-retardant carbon layer because they did not enter the heat release rate threshold window, did not identify the exposure event, the video was unreadable, the cross-sectional boundary could not be distinguished, or the thickness difference did not exceed the preset thickness difference threshold.

[0096] As shown in Table 4, this method requires that the exposure event be within or extend into the heat release rate threshold window, and that the location of the exposure event be confirmed as a location damage in the post-combustion cross-sectional image. For cases where the event does not enter the window, the video is unreadable, the cross-sectional boundary is indistinguishable, or the thickness difference does not exceed the preset thickness difference threshold, no insufficient protection judgment result is generated. Therefore, this method, by constraining the judgment output through three conditions—time window constraint, spatial location correspondence, and cross-sectional damage closure—can improve the stability and verifiability of the judgment result.

[0097] To illustrate the difference between the method of the present invention and the method based solely on the morphology of the char residue after combustion or solely on the heat release rate curve, a comparison was made between some samples as shown in Table 5.

[0098] Table 5: Comparison Results of Different Judgment Methods FR-WD-260318-01 The presence of continuous charcoal residue after combustion suggests good charcoal layer protection. It can only determine that the heat release rate within the window is increased, but cannot pinpoint the cause. Insufficient sustained protection of flame-retardant charcoal layer. A carbon layer opening occurred at 268s, and the thickness of the non-pyrolyzed substrate at the corresponding location was significantly lower than that at the reference location. FR-WD-260319-02 The charcoal residue is relatively intact. No effective heat release rate threshold window was formed. The continuous protective state of the flame-retardant charcoal layer is undetermined. Generate results indicating that the window was not entered, without forcibly determining insufficient protection. FR-PP-260323-01 A layer of char remains in some areas after combustion, making it difficult to determine the exact nature of the residue by appearance. A threshold window for the heat release rate is formed, but its spatial location cannot be determined. Insufficient sustained protection of flame-retardant charcoal layer. Substrate exposure occurred at 142s, and pyrolytic damage at the same location on the cross-section deepened. FR-CMP-260326-01 The morphology of the char residue is discontinuous. Forming a heat release rate threshold window The continuous protective state of the flame-retardant charcoal layer is undetermined. The video smoke obscures the view, making it impossible to interpret suspected nudity; therefore, no corresponding results for the heat release time of nudity are generated. FR-SH-260402-01 The small area of ​​residual char suggests poor conservation. Forming a heat release rate threshold window Insufficient sustained protection of flame-retardant charcoal layer. The carbon layer coverage was interrupted at 88s, and damage was confirmed in the corresponding cross-sectional area. FR-PU-260414-01 The appearance shows signs of carbonization and shrinkage. Forming a heat release rate threshold window The continuous protective state of the flame-retardant charcoal layer is undetermined. Although there were instances of substrate exposure, the thickness difference between the corresponding location and the reference location did not exceed the preset thickness difference threshold.

[0099] Statistical analysis revealed that among the 10 samples listed in Tables 1 to 4, 5 samples simultaneously generated results corresponding to the exposure heat release time and location damage confirmation, and also generated a result indicating insufficient sustained protection of the flame-retardant char layer. The remaining 5 samples, due to not entering the heat release rate threshold window, not identifying the exposure event, having unreadable video, indistinguishable cross-sectional boundaries, or having a thickness difference not exceeding the preset thickness difference threshold, generated a result indicating that the sustained protection status of the flame-retardant char layer could not be determined. These results demonstrate that this method does not rely solely on the appearance of the residual char or the heat release rate curve as a single indicator, but rather distinguishes between samples with insufficient protection and samples with insufficient evidence through joint verification of the time window, exposure location, and post-combustion cross-sectional damage.

[0100] For example, FR-WD-260318-01 still has continuous char residue after combustion. If we only rely on the morphology of the char residue after combustion, we are likely to assume that the char layer protection is good. If we only rely on the heat release rate curve, we can only determine that the sample formed a heat release rate threshold window from 195s to 410s, but we cannot determine the spatial location corresponding to the heat release change.

[0101] After using the method of the present invention, the sample was found to have a char layer opening event at position X42-Y27 at 268s / 6700th frame. After combustion, in the corresponding cross-sectional area CS-WD01-A, the thickness of the non-pyrolyzed substrate at the corresponding position was 5.8mm, and the thickness of the non-pyrolyzed substrate at the reference position was 10.4mm, with a thickness difference of 4.6mm, which is greater than the preset thickness difference threshold of 1.2mm. Therefore, a determination result of insufficient continuous protection of the flame-retardant char layer was generated.

[0102] For example, within the heat release rate threshold window of 60s to 110s, FR-PU-260414-01 detected a substrate exposure event at position X24-Y19 at 93s / frame 2325, thus generating a result corresponding to the exposed heat release time; however, in the corresponding cross-sectional area CS-PU01-A after combustion, the thickness of the non-pyrolyzed substrate at the corresponding position is 5.2mm, and the thickness of the non-pyrolyzed substrate at the reference position is 5.7mm, with a thickness difference of 0.5mm, which does not exceed the preset thickness difference threshold of 1.0mm. Therefore, no position damage confirmation result is generated, and the final result is that the flame-retardant char layer continuous protection status cannot be determined.

[0103] The results indicate that this method requires the formation time of the exposure event and the heat release rate threshold window result to correspond, and the result of the closed verification with the damage at the corresponding location after combustion, before generating the judgment result of insufficient continuous protection of the flame-retardant char layer.

[0104] When the result of not entering the window has been generated, the result corresponding to the exposed heat release time has not been generated, the result of location damage confirmation has not been generated, the reference section area is insufficient, or the damage closure condition is insufficient, the result of the flame-retardant carbon layer continuous protection status cannot be determined.

[0105] Specifically: when the sample under test does not form a heat release rate threshold window result, or does not form a result corresponding to the exposed heat release time, or cannot determine a comparable reference cross-sectional area in the post-combustion cross-sectional image data, or the damage comparison between the corresponding cross-sectional area and the reference cross-sectional area does not meet the conditions for generating the location damage confirmation result, the sample under test will not be judged as having insufficient flame retardant char layer protection, but will instead generate an undeterminable result for the flame retardant char layer protection status.

[0106] It should be noted that the result of "undeterminable continuous protection status of flame retardant char layer" does not mean that the continuous protection of flame retardant char layer is effective. Rather, it means that the current multi-source test data is insufficient to support the generation of a result indicating insufficient continuous protection of flame retardant char layer. This avoids the occurrence of no output or erroneous output due to missing reference cross-section area, damage comparison error, or failure to form heat release rate threshold window result.

[0107] It should be noted that: when the result corresponding to the exposed heat release time is not generated, this embodiment does not directly determine that the flame-retardant char layer is continuously effective, but rather indicates that no time-corresponding evidence for generating the determination result of insufficient continuous protection of the flame-retardant char layer has been formed; when the video data of the combustion process is complete and readable but no exposed event extending into the heat release rate threshold window result is identified, this situation is recorded as no exposed heat release time corresponding result detected, and is saved along with the determination record.

[0108] In this embodiment, through the processing of Example 4, the result corresponding to the exposure heat release time no longer stops at the phenomenon judgment in the combustion process video. Instead, it further maps the location of the exposure event to the corresponding cross-sectional area in the cross-sectional image data after combustion through the location correspondence result. The basis for generating the location damage confirmation result is that the thickness of the unpyrolyzed substrate at the corresponding location is lower than the thickness of the unpyrolyzed substrate at the reference location and the thickness difference between the two is greater than the preset thickness difference threshold. Thus, when the exposure event and the heat release rate threshold window result form a time correspondence and form a damage closure with the corresponding cross-sectional area after combustion, the result of insufficient continuous protection of the flame-retardant char layer is generated.

[0109] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended technical solutions and their equivalents.

Claims

1. A method for determining the fusion of multi-source test data of flame-retardant charcoal layers, characterized in that, Includes the following steps: S1. Acquire images of the sample before combustion, video data of the combustion process, heat release rate curve data, and cross-sectional image data after combustion. S2. Obtain the original fire zone location result based on the image of the fire-exposed surface before combustion, and obtain the heat release rate threshold window result or the non-entry window mark result based on the heat release rate curve data, the preset initial heat release rate value and the preset final heat release rate value. The preset initial heat release rate value is lower than the preset final heat release rate value. S3. When obtaining the heat release rate threshold window result, the original fire zone location result and the heat release rate threshold window result are used as the identification range. In the combustion process video data, the exposed event results that appear or continue to the heat release rate threshold window result are identified. The exposed event results include at least the time of the exposed event and the location of the exposed event. S4. When the heat release rate threshold window result is obtained and the exposure event result is identified, the ignition time of the sample to be tested is used as a unified time reference. The exposure event result is matched with the heat release rate threshold window result in time to obtain the exposure heat release time correspondence result. S5. When the result of the exposure event includes the location of the exposure event, the corresponding cross-sectional area is determined in the cross-sectional image data after combustion based on the location of the exposure event, and the location damage confirmation result is obtained based on the pyrolysis damage state of the substrate in the corresponding cross-sectional area; when both the exposure heat release time result and the location damage confirmation result are generated, the result of insufficient continuous protection of the flame-retardant char layer is generated. When the result of not entering the window has been generated, the result corresponding to the exposed heat release time has not been generated, or the result of location damage confirmation has not been generated, the result of continuous protection status of flame-retardant char layer is undeterminable.

2. The method for determining the multi-source test data fusion of flame-retardant charcoal layer according to claim 1, characterized in that, Step S1 includes: S11. Before conducting the combustion test on the sample to be tested, an image of the fire-exposed surface of the sample to be tested is acquired to obtain an image of the fire-exposed surface before combustion. S12. During the combustion test of the sample to be tested, video data of the combustion process and heat release rate curve data are collected simultaneously. After the combustion of the sample to be tested is completed, cross-sectional images of the corresponding positions of the fire-affected areas of the sample to be tested are collected to obtain cross-sectional image data after combustion. S13. Using the ignition time of the sample to be tested as a unified time reference, the video frame time in the combustion process video data and the sampling time in the heat release rate curve data are all mapped to the unified time reference.

3. The method for determining the multi-source test data fusion of flame-retardant charcoal layer according to claim 2, characterized in that, Step S2 includes: S21. Determine the fire-receiving boundary corresponding to the conical calorimetric heating area, the flame contact area, or the preset fire-receiving area in the fire-receiving surface image before combustion. S22. The fire-affected boundary and the fire-affected area enclosed by the fire-affected boundary are determined as the original fire-affected area positioning result.

4. The method for determining the multi-source test data fusion of flame-retardant char layer according to claim 3, characterized in that, Step S2 further includes: S23. Find the sampling time when the preset initial heat release rate value is first reached in the heat release rate curve data, and determine the sampling time when the preset initial heat release rate value is first reached as the window start sampling time. S24. Using the window start sampling time as the search starting point, find the sampling time in the heat release rate curve data that first reaches the preset end heat release rate value, and determine the sampling time that first reaches the preset end heat release rate value as the window end sampling time. S25. When the window start sampling time and window end sampling time are found, the time range between the window start sampling time and the window end sampling time is determined as the heat release rate threshold window result; when the window start sampling time or window end sampling time is not found, a result indicating that the window has not been entered is generated.

5. The method for determining the multi-source test data fusion of flame-retardant char layer according to claim 4, characterized in that, Step S3 includes: S31. Based on the original fire zone location results, determine the video recognition area in the combustion process video data, and based on the heat release rate threshold window results, determine the video recognition time period in the combustion process video data. S32. Identify carbon layer opening events, substrate exposure events, carbon layer curling away events, carbon layer collapse events, or carbon layer coverage interruption events within the video recognition area and the video recognition time period, and determine the identified carbon layer opening events, substrate exposure events, carbon layer curling away events, carbon layer collapse events, or carbon layer coverage interruption events as exposure events. S33. Determine the start time and location of the exposure event based on the video data of the combustion process; when the exposure event first appears within the video recognition time period, determine the time corresponding to the first video frame in which it appears as the start time of the exposure event; when the first video frame in the video recognition time period already contains an exposure state, search backwards along time for video frames at the same location where the charcoal layer coverage state changes to an exposure state, and determine the time corresponding to that video frame as the start time of the exposure event; determine the start time of the exposure event as the exposure event occurrence time, determine the location of the exposure event in the area corresponding to the original fire zone location result as the exposure event occurrence location, and form the exposure event result from the exposure event occurrence time and the exposure event occurrence location.

6. The method for determining the multi-source test data fusion of flame-retardant char layer according to claim 5, characterized in that, Step S3 further includes: S34. Locate the moment when the exposed event disappears in the video data of the combustion process; S35. When the moment when the exposure event disappears is found, the time period from the time the exposure event occurs to the time when the exposure event disappears is determined as the exposure event's continuous state. S36. When the moment when the exposure event disappears is not found, the time period from the time the exposure event occurs to the time when the combustion ends is determined as the exposure event persistence state, and the exposure event persistence state is written into the exposure event result.

7. The method for determining the multi-source test data fusion of flame-retardant char layer according to claim 6, characterized in that, Step S4 includes: S41. Based on the unified time reference, determine whether the occurrence time of the exposure event in the exposure event results is within the heat release rate threshold window results; S42. When the time of the exposure event is within the heat release rate threshold window, generate the corresponding result for the heat release time of the exposure. S43. When the exposure event occurs earlier than the window start sampling time, determine whether the exposure event continues until the window start sampling time, and generate the corresponding result of the exposure heat release time when the exposure event continues until the window start sampling time.

8. The method for determining the multi-source test data fusion of flame-retardant char layer according to claim 7, characterized in that, Step S5 includes: S51. Based on the original fire zone location results and the cross-sectional acquisition locations of the post-combustion cross-sectional image data, establish location correspondence results; S52. Based on the location correspondence results, the location of the exposed event in the exposed event results is mapped to the cross-sectional image data after combustion, and the cross-sectional area in the cross-sectional image data corresponding to the location of the exposed event is determined as the corresponding cross-sectional area. S53. Select the cross-sectional area corresponding to the location where no exposure event occurred in the post-combustion cross-sectional image data, or select the cross-sectional area adjacent to the corresponding cross-sectional area, as the reference cross-sectional area; when a comparable reference cross-sectional area cannot be determined, the generated reference cross-sectional area is insufficient.

9. The method for determining the multi-source test data fusion of flame-retardant char layer according to claim 8, characterized in that, When the ungenerated reference section area is insufficient, step S5 further includes: S54. Along the thickness direction from the fire-exposed surface to the unfired surface, obtain the unpyrolyzed substrate retention thickness at the corresponding position within the corresponding cross-sectional area. S55. Along the thickness direction from the fire-exposed surface to the unfired surface, obtain the thickness of the unpyrolyzed substrate at the reference position corresponding to the reference cross-section area. S56. When the thickness of the non-pyrolytic substrate at the corresponding position is lower than that at the reference position, and the thickness difference between the non-pyrolytic substrate at the corresponding position and the non-pyrolytic substrate at the reference position is greater than a preset thickness difference threshold, a position damage confirmation result is generated; when no position damage confirmation result is generated, the damage closure condition is insufficient.

10. The method for determining the multi-source test data fusion of flame-retardant charcoal layer according to claim 9, characterized in that, Step S5 further includes: S57. Determine whether the result corresponding to the exposure heat release time has been generated, and determine whether the location damage confirmation result has been generated; S58. When the results corresponding to the exposed heat release time and the location damage confirmation results have been generated, the flame-retardant char layer of the sample to be tested is determined to be in the heat release rate threshold window result as not providing continuous protection to the area corresponding to the original fire zone location result, and a judgment result of insufficient continuous protection of the flame-retardant char layer is generated. When the result of not entering the window has been generated, the result corresponding to the exposed heat release time has not been generated, the result of location damage confirmation has not been generated, the reference section area is insufficient, or the damage closure condition is insufficient, the result of the continuous protection status of the flame-retardant carbon layer is not determined.

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