A comprehensive evaluation method for fire hazard of materials

Abstract

This invention discloses a comprehensive evaluation method for the fire hazard of materials. It classifies the fire hazard of materials into three categories: ignition hazard, thermal hazard, and non-thermal hazard. Based on experimental data obtained from UL-94 vertical burning tests, limiting oxygen index tests, thermogravimetric analysis, and cone calorimetry, a material fire hazard evaluation index system and its weights are determined using the analytic hierarchy process (AHP). Subsequently, the experimental data are processed using an ideal solution method, and the relative similarity between the tested material and high fire hazard conditions is calculated. This data is then normalized and converted into a comprehensive fire hazard index score. This invention enables quantitative evaluation of material fire hazards and provides a theoretical basis for the selection of flame retardants and the optimization of material systems.

Description

Technical Field

[0001] This invention relates to the field of fire safety of materials, specifically a comprehensive evaluation method for the fire hazard of materials. Background Technology

[0002] The application of various materials has promoted the development of human society; however, the fire safety issues posed by flammable materials have attracted great attention. In the past, the assessment of material fire hazard largely relied on the evaluation of the material's "flammability," such as the ease of ignition and the likelihood of sustained combustion. While these parameters are indeed important, the fire hazards posed by materials are multifaceted. Non-thermal factors such as the toxicity of smoke and combustion products pose extremely high fire risks. Relying solely on the "flammability" parameter is far from sufficient to fully assess the fire hazard of materials. Therefore, the concept of a comprehensive assessment of material fire hazard, encompassing the three dimensions of heat, smoke, and toxicity, is replacing the narrow concept of material "flammability."

[0003] Currently, most comprehensive fire hazard assessment methods for materials use the analytic hierarchy process (AHP) to determine the weights of evaluation indicators. They assign values ​​to specific indicators by weighted calculations, ratios of relevant parameters, or simple normalization of relevant test data. However, they do not consider the potential impact of data distribution on the assessment results, leading to negative comprehensive fire hazard scores for some materials. Summary of the Invention

[0004] This invention addresses the problems existing in the current comprehensive evaluation methods for the fire hazard of materials by providing a comprehensive evaluation method for the fire hazard of materials based on the analytic hierarchy process (AHP) and the ideal solution method. The aim is to adjust the weights of the evaluation indicators according to specific application scenarios and to objectively assign values ​​to the evaluation indicators based on experimental data, thereby improving the applicability and scientific rigor of the comprehensive evaluation method for the fire hazard of materials.

[0005] To address the shortcomings of existing solutions, the present invention adopts the following technical solution:

[0006] The present invention provides a comprehensive evaluation method for the fire hazard of materials, characterized by a comprehensive evaluation of the ignition hazard, thermal hazard, and non-thermal hazard of the test material, and includes the following steps:

[0007] Step 1: Obtain the original data matrix of evaluation indicators based on the experiment:

[0008] 1.1 The vertical flammability rating and limiting oxygen index value of the test material were obtained based on the UL-94 vertical flammability test and the limiting oxygen index test;

[0009] 1.2. The pyrolysis characteristic parameters of the test material at heating rate a are obtained using a thermogravimetric analyzer, including the peak pyrolysis rate and the peak pyrolysis temperature. The average value of the pyrolysis characteristic parameters is obtained by averaging and used as the evaluation index parameter.

[0010] 1.3. The combustion characteristic parameters of the test material under the b type of thermal radiation flux are obtained using a cone calorimeter, including: ignition time, peak heat release rate, total heat release, peak heat release rate time, effective heat of combustion, char residue, total smoke production, CO generation and CO2 generation;

[0011] 1.4 Based on the combustion characteristic parameters of the material under type b heat radiation flux, the inherent combustion characteristic parameters are obtained by fitting the ignition time and peak heat release rate with the changes in heat radiation flux, including: critical ignition heat flux, thermal response parameters and heat release parameters.

[0012] 1) Critical ignition heat flux:

[0013] When the test material is a thermally thin material or a thermally thick material, the ignition time t of the test material can be obtained using formula (1) or formula (2). ig The critical ignition heat flux was obtained after fitting the data.

[0014] If the test material is a thermally thin material, then t ig -1 The vertical axis represents the thermal radiation flux Q of the test environment. ig Plot a scatter plot on the x-axis and perform a linear fit. The intercept of the fitted line with the x-axis is the critical ignition heat flux.

[0015] If the test material is a hot-thickness material, then t ig -0.5 The vertical axis represents the thermal radiation flux Q of the test environment. ig Plot a scatter plot on the x-axis and perform a linear fit. The intercept of the fitted line with the x-axis is the critical ignition heat flux.

[0016] When the test material is a thermally thin material (1)

[0017] When the test material is a hot-stretched material (2) In equations (1) to (2), T ig and T ∞ These represent the ignition temperature of the test material and the ambient temperature, respectively; ρ, c p d, k are the density, specific heat capacity, thickness and thermal conductivity of the material, respectively, and all are constants;

[0018] 2) Thermal response parameters:

[0019] The thermal response parameter TRP of the test material is obtained using equation (3), and expressed as t ig -0.5 The vertical axis represents the thermal radiation flux Q. ig After plotting a scatter plot on the horizontal axis, a linear fit is performed. The reciprocal of the slope of the resulting fitted curve is the thermal response parameter value of the test material.

[0020]

[0021] 3) Heat release parameters:

[0022] The heat release parameter HRP of the test material was obtained using equation (4), and the peak heat release rate PHRR was plotted as the ordinate, with the thermal radiation flux Q as the coordinate. ig After plotting a scatter plot on the horizontal axis, a linear fit is performed, and the slope of the resulting fitted line is the heat release parameter value of the test material.

[0023] HRP = Δh c / L (4)

[0024] In equation (5), Δh c L represents the heat of combustion of the test material; L represents the heat of vaporization of the test material.

[0025] The original data matrix of evaluation indicators is composed of the peak pyrolysis rate, peak pyrolysis temperature, ignition time, critical ignition heat flux, thermal response parameters, limiting oxygen index, vertical combustion level, peak heat release rate, total heat release, peak heat release rate time, heat release parameters, effective heat of combustion, char residue, total smoke production, CO generation, and CO2 generation.

[0026] Step 2: Determine the comprehensive evaluation index system and weights based on the Analytic Hierarchy Process (AHP):

[0027] 2.1 The index system of the criterion layer B under the comprehensive evaluation target layer A for determining the fire hazard of materials is respectively ignition hazard B1, thermal hazard B2, and non-thermal hazard B3;

[0028] The scheme layers for determining ignition hazard B1 are as follows: peak pyrolysis rate C 11 , peak pyrolysis temperature C 12 Ignition time C 13 Critical ignition heat flux C 14 Thermal response parameter C 15 Limiting oxygen index C 16 Vertical combustion rating C 17 ;

[0029] The scheme layers under thermal hazard B2 are defined as follows: peak heat release rate C 21 Total heat release C22 Peak time of heat release rate C 23 Heat release parameter C 24 Effective heat of combustion C 25 , residual carbon content C 26 ;

[0030] The scheme layers for non-thermal hazard B3 are determined as follows: Total smoke production C 31 CO production C 32 and CO2 production C 32 ;

[0031] 2.2 Compare the relative importance of the indicator system of the criterion layer B in pairs, and compare the relative importance of each scheme layer under the same criterion layer in pairs to obtain the indicator comparison matrix;

[0032] 2.3. Perform a consistency check on the obtained index comparison matrix using the consistency ratio calculation method in the analytic hierarchy process. If the consistency check result CR is less than the set threshold, the consistency check is passed; otherwise, return to step 2.2 and execute sequentially.

[0033] 2.4. Based on the indicator comparison matrix that passed the consistency test, calculate the indicator weight matrix c of criterion layer B to target layer A. BA The index weight matrix c of scheme layer C on criterion layer B CB Therefore, the index weight matrix c of scheme layer C to target layer A is calculated using equation (5). CA ;

[0034] c CA =c BA c CB (5)

[0035] Step 3: Comprehensive evaluation based on the ideal solution:

[0036] 3.1. Based on the indicator attributes, use equation (6) or equation (7) to perform homogenization processing on the original data matrix of the evaluation indicators, and obtain the homogenized minimal indicator data x`:

[0037] x` = 1 / x , x>0 (6)

[0038] x`=Mx,x≤0 (7)

[0039] In equation (6) or (7), M is the maximum value of the original data matrix of the evaluation index of the test material under b kinds of thermal radiation flux; x represents the extremely large index data in the original data matrix of the evaluation index.

[0040] The same-direction data matrix is ​​composed of the extremely small index data x` after the same-direction processing and the extremely small index data in the original data matrix of the evaluation index;

[0041] 3.2 After normalizing the homogenized data matrix, the normalized homogenized data matrix is ​​obtained;

[0042] 3.3 Based on the fact that the normalized data matrix is ​​of the same direction, the positive ideal solution Z is determined using equations (8) and (9) respectively. + and negative ideal solution Z - :

[0043]

[0044]

[0045] In equations (8) and (9), z ij Let m be the raw data of the j-th evaluation index for the i-th test material, and m be the number of types of raw data for evaluation indices. Let m be the maximum value of the original data for the m-th evaluation index of i test materials under b types of thermal radiation flux. Let [maxz] be the minimum value of the raw data of the m-th evaluation index for i test materials under b types of thermal radiation flux. ij [)] is the matrix of maximum values ​​of the original data of evaluation indicators for i test materials under b kinds of thermal radiation flux, [(minz ij [)] is the minimum value matrix of the original data of evaluation indicators for i test materials under b kinds of thermal radiation flux;

[0046] 3.4. Determine the relationship between the i-th test material and the positive ideal solution Z according to equations (10) and (11). + The degree of fire hazard is relatively similar and the negative ideal solution Z - The degree of fire hazard is relatively similar

[0047]

[0048]

[0049] 3.5. Calculate the relative similarity C between the i-th test material and the high fire hazard situation according to formula (12). i :

[0050]

[0051] 3.6. By normalizing the data, the relative similarity between each test material and the high fire hazard situation under the b type of heat radiation flux is converted into a comprehensive fire hazard index score, thereby quantitatively evaluating the fire hazard of each test material under the b type of heat radiation flux.

[0052] Compared with existing technologies, the beneficial effects of the present invention are as follows:

[0053] 1) This invention addresses the limitations of relying solely on the "flammability" parameter to assess the fire hazard of materials. It expands the comprehensive evaluation index system for the fire hazard of materials to include three dimensions: ignition hazard, thermal hazard, and non-thermal hazard, encompassing heat, smoke, and toxicity. In particular, the introduction of inherent combustion characteristic parameters such as critical ignition heat flux and thermal response parameters makes the evaluation index system more diversified and essential.

[0054] 2) This invention uses an ideal solution method to process relevant experimental data to increase the scientificity and objectivity of index assignment.

[0055] 3) This invention uses the analytic hierarchy process (AHP) to determine comprehensive evaluation indicators for the fire hazard of materials and obtain an indicator weight matrix. Based on the obtained indicator weight matrix, relevant experimental data is processed using an ideal solution method to obtain a comprehensive fire hazard evaluation score. The comprehensive evaluation process for the fire hazard of materials is divided into three steps: obtaining evaluation indicator parameters based on experiments, determining the comprehensive evaluation indicator system and weights based on the AHP, and conducting a comprehensive evaluation based on an ideal solution. Therefore, this invention provides a complete and scientific method for the comprehensive evaluation of the fire hazard of materials, which can comprehensively quantify the fire hazard of materials and provide a theoretical basis for improving the fire resistance performance of materials and designing flame-retardant materials. Attached Figure Description

[0056] Figure 1 This is a flowchart of the comprehensive evaluation method for the fire hazard of materials according to the present invention. Detailed Implementation

[0057] In this embodiment, a comprehensive evaluation method for the fire hazard of materials is provided, such as... Figure 1 As shown, six test materials with epoxy resin as the matrix were used as research objects (the test samples were of the same size), and the fire hazard of the six test materials was evaluated by this invention.

[0058] Step 1: Obtain the original data matrix of evaluation indicators based on the experiment:

[0059] 1.1 The vertical flammability rating and limiting oxygen index value of the test material were obtained based on the UL-94 vertical flammability test and the limiting oxygen index test;

[0060] 1.2. Based on thermogravimetric analysis, the pyrolysis characteristic parameters of the material at four heating rates (5, 10, 20 and 40℃ / min) were obtained, including the peak pyrolysis rate and the peak pyrolysis temperature. The average value of the pyrolysis characteristic parameters was obtained by averaging and used as the evaluation index parameter.

[0061] 1.3. Based on the cone calorimeter, the test material was obtained under four different thermal radiation fluxes (25, 35, 50, and 65 kW / m²). 2 Combustion characteristic parameters of the sample include: ignition time, peak heat release rate, total heat release, peak heat release rate time, effective heat of combustion, char residue, total smoke production, CO generation, and CO2 generation.

[0062] 1.4. Based on the material under four thermal radiation fluxes (25, 35, 50 and 65 kW / m²) 2 The combustion characteristic parameters of the ignition heat flux are obtained by fitting the curves of the ignition time and the peak heat release rate with the changes in heat radiation flux. The inherent combustion characteristic parameters include: critical ignition heat flux, thermal response parameters and heat release parameters.

[0063] 1) Critical ignition heat flux:

[0064] When the test material is a thermally thin material or a thermally thick material, the ignition time t of the test material can be obtained using formula (1) or formula (2). ig The critical ignition heat flux was obtained after fitting the data.

[0065] If the test material is a thermally thin material, then t ig -1 The vertical axis represents the thermal radiation flux Q of the test environment. ig Plot a scatter plot on the x-axis and perform a linear fit. The intercept of the fitted line with the x-axis is the critical ignition heat flux.

[0066] If the test material is a hot-thickness material, then t ig -0.5 The vertical axis represents the thermal radiation flux Q of the test environment. ig Plot a scatter plot on the x-axis and perform a linear fit. The intercept of the fitted line with the x-axis is the critical ignition heat flux.

[0067] When the test material is a thermally thin material (1)

[0068] When the test material is a hot-stretched material (2) In equations (1) to (2), T ig and T ∞ These represent the ignition temperature of the test material and the ambient temperature, respectively; ρ, c pd, k are the density, specific heat capacity, thickness and thermal conductivity of the material, respectively, and all are constants.

[0069] Since it was impossible to determine whether the six test materials were hot-thin or hot-thick materials, the six test materials were treated as hot-thin or hot-thick materials for fitting calculations to obtain the critical ignition heat flux and the degree of fitting in the two cases. The material type was judged based on the degree of fitting and whether the critical ignition heat flux was negative. The test materials can be regarded as the material type with a high degree of fitting and no negative critical ignition heat flux.

[0070] 2) Thermal response parameters:

[0071] The thermal response parameter TRP of the test material is obtained using equation (3), and expressed as t ig -0.5 The vertical axis represents the thermal radiation flux Q. ig After plotting a scatter plot on the horizontal axis, a linear fit is performed. The reciprocal of the slope of the resulting fitted curve is the thermal response parameter value of the test material.

[0072]

[0073] 3) Heat release parameters:

[0074] The heat release parameter HRP of the test material was obtained using equation (4), and the peak heat release rate PHRR was plotted as the ordinate, with the thermal radiation flux Q as the coordinate. ig After plotting a scatter plot on the horizontal axis, a linear fit is performed, and the slope of the resulting fitted line is the heat release parameter value of the test material.

[0075] HRP = Δh c / L (4)

[0076] In equation (5), Δh c L represents the heat of combustion of the test material; L represents the heat of vaporization of the test material.

[0077] The original data matrix of the evaluation index consists of the peak pyrolysis rate, peak pyrolysis temperature, ignition time, critical ignition heat flux, thermal response parameters, limiting oxygen index, vertical combustion rating, peak heat release rate, total heat release, peak heat release rate time, heat release parameters, effective heat of combustion, char residue, total smoke production, CO generation, and CO2 generation.

[0078] Raw data for the six test materials under four different thermal radiation fluxes can then be obtained. The six test materials at 35 kW / m²... 2 The raw data are shown in Table 1, 25, 50 and 65 kW / m 2 The original data will not be described in detail here.

[0079] Table 1. Raw data for comprehensive fire hazard evaluation of test materials (35kW / m³) 2 )

[0080]

[0081]

[0082] Step 2: Determine the evaluation index system and weights based on the analytic hierarchy process (AHP):

[0083] 2.1 The index system of the criterion layer B under the comprehensive evaluation target layer A for determining the fire hazard of materials is respectively ignition hazard B1, thermal hazard B2, and non-thermal hazard B3;

[0084] The scheme layers for determining ignition hazard B1 are as follows: peak pyrolysis rate C 11 , peak pyrolysis temperature C 12 Ignition time C 13 Critical ignition heat flux C 14 Thermal response parameter C 15 Limiting oxygen index C 16 Vertical combustion rating C 17 ;

[0085] The scheme layers under thermal hazard B2 are defined as follows: peak heat release rate C 21 Total heat release C 22 Peak time of heat release rate C 23 Heat release parameter C 24 Effective heat of combustion C 25 , residual carbon content C 26 ;

[0086] The scheme layers for non-thermal hazard B3 are determined as follows: Total smoke production C 31 CO production C 32 and CO2 production C 32 .

[0087] The comprehensive evaluation system and index attributes of material fire hazard are shown in Table 2. The smaller the index value, the greater the fire hazard of the material. The index is called a very small index. Conversely, the larger the index value, the greater the fire hazard of the material. The index is called a very large index.

[0088] Table 2. Comprehensive Evaluation System and Index Attributes of Fire Hazard of Test Materials

[0089]

[0090]

[0091] 2.2 Compare the relative importance of the indicator system of the criterion layer B in pairs, and compare the relative importance of each scheme layer under the same criterion layer in pairs to obtain the indicator comparison matrix;

[0092] 2.3. Perform a consistency test on the obtained index comparison matrix using the consistency ratio calculation method in the analytic hierarchy process. If the consistency test result CR is less than 0.1, the consistency test is passed; otherwise, return to step 2.2 and execute sequentially.

[0093] 2.4. Based on the indicator comparison matrix that passed the consistency test, calculate the indicator weight matrix c of criterion layer B to target layer A. BA The index weight matrix c of scheme layer C on criterion layer B CB Therefore, the index weight matrix c of scheme layer C to target layer A is calculated using equation (5). CA ;

[0094] c CA =c BA c CB (5)

[0095] Given the nature of epoxy resin matrix, which easily causes coupled thermal and toxic hazards, the weight calculation results must basically meet the requirements of the three dimensions of heat, smoke, and toxicity. The final comprehensive fire hazard evaluation index weights are shown in Table 2, and the weight determination is relatively reasonable. The weight index matrix is ​​(0.0138, 0.0138, 0.0233, 0.0577, 0.0138, 0.0373, 0.0855, 0.1654, 0.1227, 0.0365, 0.0532, 0.0620, 0.0233, 0.0866, 0.1574, 0.0477).

[0096] Table 3 Weights of Comprehensive Evaluation Indicators for Fire Hazard of Test Materials

[0097]

[0098]

[0099] Step 3: Comprehensive evaluation based on the ideal solution:

[0100] 3.1. Based on the indicator attributes, the original data matrix of the evaluation indicators is processed using equation (6) or equation (7) to obtain the minima index data x' after the processing. Thus, the minima index data after the processing and the minima index data in the original data matrix of the evaluation indicators together form the uniform data matrix:

[0101] x` = 1 / x, x > 0 (6)

[0102] x`=Mx,x≤0 (7)

[0103] In equation (6) or equation (7), M is the maximum value of the original data of the evaluation index of the i-th test material under the b-type thermal radiation flux; x represents the extremely large index data in the original data of the evaluation index.

[0104] In addition, the vertical flammability rating can be set to 1 for V-0, 0.75 for V-1, 0.5 for V-2, and 0 for NR (no rating).

[0105] The raw data of the six test materials under four thermal radiation fluxes were processed to achieve data attribute homogenization, that is, to transform extremely large indicators into extremely small indicators. The six test materials under 35 kW / m² thermal radiation fluxes... 2 The results of the homogenization treatment at 25, 50, and 65 kW / m² are shown in Table 4. 2 The results of the homogenization process are not elaborated here.

[0106] Table 4. Results of homogenization processing of raw data for comprehensive fire hazard evaluation of test materials (35kW / m³) 2 )

[0107]

[0108]

[0109] 3.2 After normalizing the homogenized data matrix, the normalized homogenized data matrix is ​​obtained;

[0110] The raw data of the six test materials under four different thermal radiation fluxes were normalized and then processed to achieve the same direction. The data for the six test materials at 35 kW / m² were then analyzed. 2 The normalization results for 25, 50, and 65 kW / m³ are shown in Table 5. 2 The normalization results are not elaborated here.

[0111] Table 5. Normalized results of comprehensive fire hazard assessment data for tested materials (35kW / m³) 2 )

[0112]

[0113] 3.3. Based on the normalized and oriented data matrix, the positive ideal solution Z is determined using equations (8) and (9) respectively. + and negative ideal solution Z - :

[0114]

[0115]

[0116] In equations (8) and (9), zij Let m be the raw data of the j-th evaluation index for the i-th test material, and m be the number of types of raw data for evaluation indices. Let m be the maximum value of the original data for the m-th evaluation index of i test materials under b types of thermal radiation flux. Let [maxz] be the minimum value of the raw data of the m-th evaluation index for i test materials under b types of thermal radiation flux. ij [)] is the matrix of maximum values ​​of the original data of evaluation indicators for i test materials under b kinds of thermal radiation flux, [(minz ij [)] is the minimum value matrix of the original data of evaluation indicators for i test materials under b kinds of thermal radiation flux;

[0117] 3.4. Determine the relationship between the i-th test material and the positive ideal solution Z according to equations (10) and (11). + The degree of fire hazard is relatively similar and the negative ideal solution Z - The degree of fire hazard is relatively similar

[0118]

[0119]

[0120] 3.5. Calculate the relative similarity C between the i-th test material and the high fire hazard situation according to formula (12). i :

[0121]

[0122] Based on 25, 35, 50 and 65 kW / m 2 The experimental data under thermal radiation flux can be used to obtain the results for six materials at 25, 35, 50, and 65 kW / m². 2 The relative similarity between the thermal radiation flux and the high fire hazard situation is shown in Table 6.

[0123] Table 6 shows the relative similarity of the tested materials to high fire hazard conditions.

[0124]

[0125] 3.6. The relative similarity (C) of the six test materials to high fire hazard conditions under four different thermal radiation fluxes was determined through normalization. i Convert to a percentage system, and assign the material with the lowest fire hazard level, i.e., 65kW / m². 2 The fire hazard comprehensive index score of material 1 was set to 100, thereby quantitatively evaluating the fire hazard of the six test materials under four heat radiation fluxes, as shown in Table 7.

[0126] Table 7. Comprehensive Evaluation Scores of Fire Hazard of Test Materials

[0127]

[0128] In summary, the method of this invention enables quantitative evaluation of the fire hazard of materials and provides a theoretical basis for the selection of flame retardants and the optimization of material systems.

Claims

1. A comprehensive evaluation method for the fire hazard of materials, characterized in that it comprehensively evaluates the ignition hazard, thermal hazard, and non-thermal hazard of the test material, and includes the following steps: Step 1: Obtain the original data matrix of evaluation indicators based on the experiment: 1.1 The vertical flammability rating and limiting oxygen index value of the test material were obtained based on the UL-94 vertical flammability test and the limiting oxygen index test; 1.

2. The pyrolysis characteristic parameters of the test material at heating rate a are obtained using a thermogravimetric analyzer, including the peak pyrolysis rate and the peak pyrolysis temperature. The average value of the pyrolysis characteristic parameters is obtained by averaging and used as the evaluation index parameter. 1.

3. The combustion characteristic parameters of the test material under the b type of thermal radiation flux are obtained using a cone calorimeter, including: ignition time, peak heat release rate, total heat release, peak heat release rate time, effective heat of combustion, char residue, total smoke production, CO generation and CO2 generation; 1.4 Based on the combustion characteristic parameters of the material under type b heat radiation flux, the inherent combustion characteristic parameters are obtained by fitting the ignition time and peak heat release rate with the changes in heat radiation flux, including: critical ignition heat flux, thermal response parameters and heat release parameters. 1) Critical ignition heat flux: When the test material is a thermally thin material or a thermally thick material, the ignition time of the test material can be obtained using formula (1) or formula (2). t ig The critical ignition heat flux was obtained after fitting the data. If the test material is a thermally thin material, then... t ig -1 The vertical axis represents the thermal radiation flux of the test environment. Q ig Plot a scatter plot on the x-axis and perform a linear fit. The intercept of the fitted line with the x-axis is the critical ignition heat flux. If the test material is a hot-thickness material, then... t ig -0.5 The vertical axis represents the thermal radiation flux of the test environment. Q ig Plot a scatter plot on the x-axis and perform a linear fit. The intercept of the fitted line with the x-axis is the critical ignition heat flux. When the test material is a thermally thin material (1) When the test material is a hot-thickness material (2) In equations (1) to (2), T ig and T ∞ These represent the ignition temperature of the test material and the ambient temperature, respectively; ρ, c p d, k are the density, specific heat capacity, thickness and thermal conductivity of the material, respectively, and all are constants; 2) Thermal response parameters: The thermal response parameter TRP of the test material is obtained using equation (3), and then... t ig -0.5 The vertical axis represents the thermal radiation flux. Q ig After plotting a scatter plot on the horizontal axis, a linear fit is performed. The reciprocal of the slope of the resulting fitted curve is the thermal response parameter value of the test material. (3) 3) Heat release parameters: The heat release parameter HRP of the test material was obtained using equation (4), and the peak heat release rate PHRR was plotted as the ordinate, with the heat radiation flux as the ordinate. Q ig After plotting a scatter plot on the horizontal axis, a linear fit is performed, and the slope of the resulting fitted line is the heat release parameter value of the test material. (4) In equation (4), To test the heat of combustion of the material; To test the heat of vaporization of the material; The original data matrix of evaluation indicators is composed of the peak pyrolysis rate, peak pyrolysis temperature, ignition time, critical ignition heat flux, thermal response parameters, limiting oxygen index, vertical combustion level, peak heat release rate, total heat release, peak heat release rate time, heat release parameters, effective heat of combustion, char residue, total smoke production, CO generation, and CO2 generation. Step 2: Determine the comprehensive evaluation index system and weights based on the Analytic Hierarchy Process (AHP): 2.1 The index system of the criterion layer B under the comprehensive evaluation target layer A for determining the fire hazard of materials is respectively ignition hazard B1, thermal hazard B2, and non-thermal hazard B3; The scheme layers for determining ignition hazard B1 are as follows: peak pyrolysis rate C 11 , peak pyrolysis temperature C 12 Ignition time C 13 Critical ignition heat flux C 14 Thermal response parameter C 15 Limiting oxygen index C 16 Vertical combustion rating C 17 ; The scheme layers under thermal hazard B2 are defined as follows: peak heat release rate C 21 Total heat release C 22 Peak time of heat release rate C 23 Heat release parameter C 24 Effective heat of combustion C 25 , residual carbon content C 26 ; The scheme layers for non-thermal hazard B3 are determined as follows: Total smoke production C 31 CO production C 32 and CO2 production C 32 ; 2.2 Compare the relative importance of the indicator system of the criterion layer B in pairs, and compare the relative importance of each scheme layer under the same criterion layer in pairs to obtain the indicator comparison matrix; 2.

3. The consistency of the obtained index comparison matrix is ​​tested using the consistency ratio calculation method in the Analytic Hierarchy Process (AHP). If the consistency test results are satisfactory... CR If the value is less than the set threshold, the consistency check has passed. Otherwise, return to step 2.2 and execute sequentially; 2.

4. Based on the index comparison matrix that passed the consistency test, calculate the index weight matrix of criterion layer B to target layer A. The index weight matrix of scheme layer C to criterion layer B Therefore, the index weight matrix of scheme layer C to target layer A is calculated using equation (5). ; (5) Step 3: Comprehensive evaluation based on the ideal solution: 3.

1. Based on the indicator attributes, use equation (6) or equation (7) to perform homogenization processing on the original data matrix of the evaluation indicators, and obtain the homogenized minimal indicator data. : (6) (7) In equation (6) or equation (7), The maximum value of the original data matrix of the evaluation index of the test material under b types of thermal radiation flux; This represents the extremely large indicator data in the original data matrix of the evaluation indicators. Minimal indicator data after homogenization The original data matrix of evaluation indicators and the extremely small indicator data form a homogeneous data matrix; 3.2 After normalizing the homogenized data matrix, the normalized homogenized data matrix is ​​obtained; 3.

3. Based on the normalized and oriented data matrix, the positive ideal solution is determined using equations (8) and (9) respectively. and negative ideal solution : (8) (9) In equations (8) and (9), Let m be the raw data of the j-th evaluation index for the i-th test material, and m be the number of types of raw data for evaluation indices. Let m be the maximum value of the original data for the m-th evaluation index of i test materials under b types of thermal radiation flux. Let m be the minimum value of the original data for the m-th evaluation index of i test materials under b types of thermal radiation flux. Let be the matrix of maximum values ​​of the original data for evaluation indicators of i test materials under b types of thermal radiation flux. Let be the minimum value matrix of the original data of the evaluation indexes for i test materials under b kinds of thermal radiation flux; 3.

4. Determine the relationship between the i-th test material and the positive ideal solution according to equations (10) and (11). The fire hazard levels are relatively similar. and negative ideal solutions The fire hazard levels are relatively similar. : (10) (11) In equations (10) and (11), for The weight of the j-th evaluation index on the target layer A; 3.

5. Calculate the relative similarity between the i-th test material and the high fire hazard situation according to formula (12). : (12) 3.

6. By normalizing the data, the relative similarity between each test material and the high fire hazard situation under the b type of heat radiation flux is converted into a comprehensive fire hazard index score, thereby quantitatively evaluating the fire hazard of each test material under the b type of heat radiation flux.

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