Health evaluation method and system for isomerous hybrid crash beam

Abstract

The present application relates to the technical field of mechanical structure health evaluation, and particularly relates to a health degree evaluation method and system for a heterogeneous hybrid crash beam, which comprises the following steps: at least three metal electrode sheets are arranged in the crash beam, initial resistance data is collected as a unique birth fingerprint and stored; a segmented resistance measurement path is constructed based on adjacent electrodes; resistance response data is collected under the condition of applying quasi-static load; normalization processing based on temperature parameters is performed on the collected data, a second-order thermal sensitivity model is used to map the measured resistance to a standard resistance, and comparison is made with the birth fingerprint, and if the deviation exceeds the tolerance, the evaluation is terminated; interface debonding damage is determined by a hysteresis area operator, and fiber fracture damage is determined by a step residual operator. The present application realizes quantitative differentiation of interface debonding and material fracture in a heterogeneous hybrid structure, eliminates temperature drift interference, can be implemented on site during regular maintenance, and is suitable for full life cycle health management of automobile crash beams.

Description

Technical Field

[0001] This invention belongs to the field of mechanical structure health evaluation technology, and in particular relates to a method and system for evaluating the health of heterogeneous hybrid anti-collision beams. Background Technology

[0002] With increasing demands for lightweight and safety performance in automobiles, heterogeneous hybrid structures composed of aluminum alloys and carbon fiber reinforced polymers (CFRP) are being used more and more widely. However, such structures face the following technical challenges during service: First, interface failures are often insidious. Due to mismatch in coefficients of thermal expansion (CTE) or alternating loads, microscopic debonding, invisible to the naked eye, can easily occur at the interface between metals and composite materials. This type of damage cannot be identified by visual inspection in its early stages, but may suddenly propagate under subsequent high-load conditions, leading to structural failure.

[0003] II. Ambiguity of failure modes; When a structure experiences mechanical property degradation, traditional methods cannot distinguish between "interface debonding" and "material fracture," two fundamentally different types of mechanical failure. Interface debonding is a progressive damage to the interface layer, and its repair strategies (such as re-bonding) differ significantly from those for fiber fracture (which requires replacement of the entire component). Confusing the two will lead to inappropriate repair decisions.

[0004] III. Invisible collision damage; Low-speed impacts can cause delamination between the internal layers of the composite material, while the external aluminum alloy beam shows no significant deformation. This type of "hidden damage" is easily overlooked during routine maintenance, posing a significant safety hazard.

[0005] IV. Environmental noise interference; The resistance of heterogeneous materials fluctuates drastically with temperature, and traditional simple resistance measurements cannot distinguish between "temperature drift" and "damage". Temperature drift is a shift in the electrical parameters of a material caused by changes in ambient temperature. This shift is completely unrelated to whether the structure is damaged, but its magnitude is often greater than the weak signal generated by early damage, causing the traditional resistance threshold judgment method to fail.

[0006] V. Testing Costs and Efficiency; Existing flaw detection methods (ultrasound, X-ray, infrared thermal imaging) are expensive, complex to operate, and require highly skilled personnel, making them unsuitable for routine after-sales maintenance and lacking convenient, standardized quantitative assessment methods. Summary of the Invention

[0007] In view of this, the present invention aims to provide a method and system for evaluating the health of heterogeneous hybrid anti-collision beams, so as to solve the above-mentioned problems in the background technology. By designing physical reference points, constructing segmented electrical paths, second-order thermal normalization mapping, and decoupling hysteresis and step double operators, the service health of heterogeneous hybrid structures is evaluated.

[0008] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A method for evaluating the health of heterogeneous hybrid anti-collision beams includes the following steps: S1: At least three metal electrode plates are installed inside the crash beam, arranged along the length of the crash beam. At least one metal electrode plate is located in the bending neutral region of the crash beam, serving as a physical reference point with minimal strain response and symmetrical temperature response. The remaining metal electrode plates are symmetrically arranged on both sides of the metal electrode plate within the bending neutral region, with the two metal electrode plates at both ends positioned close to the ends of the crash beam to capture local strain fluctuations. Initial resistance data of each metal electrode plate is collected under factory conditions and at a standard reference temperature, serving as the unique "birth fingerprint" of the crash beam. And store it; S2: Construct a segmented resistance measurement path based on two adjacent metal electrode plates on the anti-collision beam; so that each segmented resistance measurement path corresponds to the mechanical response of different regions of the structure; S3: Under the condition of applying a preset load, collect the resistance response data of each segmented resistance measurement path; S4: Before damage identification, the collected resistance response data is normalized based on temperature parameters to map the resistance data to standard resistance data at a preset reference temperature; the standard resistance data serves as the sole input data for subsequent damage determination. S5: Based on the standard resistance data preprocessed in step S4, the damage type is distinguished according to the electrical response pattern formed by the difference in response sensitivity of each segmented resistance measurement path to the damage type; among them: when the resistance curve with load changes with energy dissipation characteristics, it is determined to be interface damage; when the resistance shows a permanent step change after unloading, it is determined to be material fracture.

[0009] Furthermore, in step S4, the acquired resistance response data undergoes temperature-based normalization to compensate for temperature and strain coupling interference, including the following steps: S41: Collects the core equilibrium temperature of the metal electrode sheet; S42: Differential calculation is performed using two segmented resistance measurement paths symmetrically set on both sides of the bending neutral region of the anti-collision beam to eliminate local temperature gradient interference; S43: The acquisition resistance is mapped to a standard reference temperature by using the core equilibrium temperature and a second-order thermal sensitivity model. The mapping formula is as follows: ; in: For standard resistance data, To collect resistance, α、β For the pre-calibrated first and second order coefficients of thermal sensitivity, To collect the core equilibrium temperature, T ref Birth fingerprints Standard reference temperature during data collection.

[0010] Furthermore, in step S42, the specific steps for eliminating local temperature gradient interference include: S421: Preprocess the resistance response data collected in step S3. Collect resistance data under static conditions continuously at a sampling frequency of 10-1000Hz within a time window of 1-30s. Calculate the average value of the current resistance data as the instantaneous zero reference value and deduct it from the subsequent measurement data. S422: Standard resistance data based on S421 self-calibration Calculate its relationship with birth fingerprints The relative offset; this offset is used as the initial damage weight and is included in the interface debonding determination and material fracture determination in the subsequent step S5 in the form of a fixed bias. S423: Utilizing two segmented resistance measurement paths symmetrically set on both sides of the physical reference point C, namely segment AC and segment BC, differential calculation is performed: ; In the formula: ΔR grad For differential operational resistors, The resistance value of the AC segment resistance measurement path. The resistance value of the resistance measurement path for segment BC.

[0011] Furthermore, in step S4, the standard resistance data is compared with the birth fingerprint pre-stored in step S1. A comparison is performed to execute a determination; when the standard resistance data is relative to the birth fingerprint... When the deviation exceeds the preset tolerance range, the current environment or state is determined to not meet the evaluation conditions, and the health assessment process is terminated.

[0012] Furthermore, in step S5, the energy dissipation characteristics of the resistance-load variation curve are quantified by calculating the hysteresis area enclosed by the loading and unloading paths. This hysteresis area serves as the interface debonding damage determination operator. sIt is obtained by numerical integration of discrete sampling points along the loading and unloading paths; when When the value exceeds the preset interface dissipation threshold, it is determined that the mechanical anchoring point between the metal layer 161 and the fiber-reinforced composite material layer is loose or microscopically debonded.

[0013] Furthermore, the interface debonding damage determination operator The calculation formula is: ; In the formula: This is the operator for determining interface debonding damage; ∮ represents full path integration over a complete loading and unloading process. R The resistance value is a real-time segmented value that varies with the load and is expressed in ohms. F The quasi-static excitation force is applied to the middle of the crash beam, and the unit is Newton. dF Quasi-static excitation force F The differential; when When the interface dissipation threshold is reached, it is determined that the mechanical anchoring point between the metal and the composite material is loose or there is microscopic debonding.

[0014] Furthermore, in step S5, material fracture damage is monitored by the step offset of the reference resistance after unloading. δ To determine the step offset of the reference resistor δ The calculation formula is: ; In the formula: This is the reference resistance step offset, used to quantify the permanent structural step increment caused by the fracture of the conductive network (carbon fiber bundle); The reference resistance after testing is the residual resistance value after the standard load is applied and removed. For testing The initial reference resistance, i.e., the resistance value before the load is applied; This indicates that the process is performed under a fully unloaded state to eliminate the instantaneous contribution of elastic strain to the resistance. When δ is greater than the preset structural damage threshold and the slope of the resistance-load relationship curve shows a step change, it is determined to be brittle fracture or delamination damage of the fiber bundle.

[0015] A heterogeneous hybrid anti-collision beam health assessment system includes a sensor unit, an excitation unit, a data acquisition unit, a processing unit, a storage unit, and a communication unit. The sensor unit includes at least three metal electrode plates disposed within the anti-collision beam to sense resistance and temperature signals along each segmented resistance measurement path. A segmented resistance measurement path is formed between two adjacent metal electrode plates. The excitation unit applies a preset quasi-static load to the anti-collision beam. The data acquisition unit, connected to the sensor unit, acquires resistance response data and temperature data for each segmented resistance measurement path. The processing unit, connected to both the data acquisition unit and the excitation unit, controls the excitation unit to apply the quasi-static load and receives the resistance response and temperature data acquired by the data acquisition unit. It also performs temperature-based normalization processing, standard resistance analysis, and a birth fingerprint analysis. The system includes comparison and judgment, dynamic benchmark drift compensation, interface debonding damage judgment, material fracture damage judgment, and health report generation; the storage unit is connected to the processing unit to store birth fingerprints. The data and historical service records are connected to the communication unit and processing unit for data interaction with the cloud database. The health reports generated by the processing unit are reported to the cloud database to update the service records of the parts.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) This invention realizes the quantitative distinction between the failure modes of the mechanical interface and the material itself in heterogeneous hybrid structures. By constructing a dual-operator decoupling mechanism of hysteresis area operator and step residual operator, the energy dissipation characteristics of the interface under cyclic load and the degree of permanent damage to the conductive network are characterized respectively, thereby accurately distinguishing the two essentially different failure modes of interface debonding and material fracture, providing a technical basis for accurate maintenance decision-making.

[0017] (2) This invention creates a dual-reference physical origin for strain neutrality and thermal equilibrium. This node simultaneously satisfies the minimum strain response and the symmetrical reference condition for temperature response, thereby eliminating the coupling between strain interference and temperature gradient interference. This greatly improves the signal stability under complex service environments and ensures that the input data for subsequent damage assessment is accurate and reliable.

[0018] (3) This invention addresses the physical characteristic of the nonlinear and drastic temperature fluctuations in the resistance of the aluminum alloy layer and the fiber-reinforced composite material layer in heterogeneous hybrid structures. By using a second-order thermal sensitivity matrix, it forces the measured resistance data under different time, space, and temperature conditions to be projected onto a reference state identical to the part's "birth fingerprint" at the time of manufacture, achieving cross-temporal reference alignment and accurate extraction of damage signals. Combined with the birth fingerprint comparison and termination assessment threshold mechanism, it ensures the absolute rigor of the health assessment conclusion.

[0019] (4) This invention transforms the traditional damage assessment that relies on manual experience into a standardized operator assessment. Through multi-dimensional quantitative indicators such as energy dimension (hysteresis area), structural dimension (reference resistance step offset), and spatial dimension (path deviation), it provides standardized technical support for the full life cycle management of crash beams. Inspection personnel do not need to have professional flaw detection experience to make maintenance decisions quickly based on the operator assessment results.

[0020] (5) The present invention adopts a technical solution of resistance detection and quasi-static load excitation, which does not require expensive ultrasonic, X-ray or infrared thermal imaging equipment. It only requires pre-embedded metal electrode plates in the anti-collision beam and portable testing tools to quickly complete the health assessment at the conventional automotive after-sales maintenance site, which has good engineering promotion value. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A flowchart of the health evaluation method for heterogeneous hybrid anti-collision beams in an embodiment of the present invention; Figure 2 A schematic diagram of the connection structure between the anti-collision beam and the metal electrode sheet in the heterogeneous hybrid anti-collision beam health evaluation method of this invention embodiment; Figure 3 for Figure 2 The main view; Figure 4 for Figure 3 DD side sectional view; Figure 5 for Figure 4 Enlarged structural diagram of section E in the middle; Figure 6 The resistance curve as a function of load under a fully healthy state (elastic stage) is evaluated by the health evaluation method of the heterogeneous hybrid anti-collision beam in an embodiment of the present invention. Figure 7 The resistance curve as a function of load under the interface debonding damage state evaluated by the health evaluation method of the heterogeneous hybrid anti-collision beam in an embodiment of the present invention; Figure 8 The resistance curve as a function of load under fiber fracture damage state is evaluated by the health evaluation method of the heterogeneous hybrid anti-collision beam in an embodiment of the present invention. Figure 9 The structural block diagram of the heterogeneous hybrid anti-collision beam health evaluation system according to an embodiment of the present invention is shown.

[0022] Explanation of reference numerals in the attached figures: 10. Sensor unit; 11. Excitation unit; 12. Acquisition unit; 13. Processing unit; 14. Storage unit; 15. Communication unit; 16. Anti-collision beam; 101. Metal electrode sheet; 161. Metal layer; 162. Glass fiber layer; 163. Carbon fiber layer. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0024] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0028] like Figure 1 As shown, a method for evaluating the health of heterogeneous hybrid anti-collision beams includes the following steps: S1: Three metal electrode plates 101 are installed inside the anti-collision beam 16. The three metal electrode plates 101 are arranged along the length of the anti-collision beam 16. One metal electrode plate 101 is located in the bending neutral region of the anti-collision beam 16 and serves as a physical reference point with minimum strain response and symmetrical temperature response. The remaining two metal electrode plates 101 are symmetrically arranged on both sides of the metal electrode plate 101 in the bending neutral region, with the two metal electrode plates 101 located at both ends close to the two ends of the anti-collision beam 16 (symmetrically distributed at the edge of the energy absorption region) to capture local strain fluctuations. The initial resistance data of each metal electrode plate 101 is collected under factory conditions (unloaded, undamaged initial state) and at a standard reference temperature (25°C) as the unique "birth fingerprint" of the anti-collision beam 16. And store it.

[0029] The anti-collision beam 16 is composed of a metal layer 161 and a fiber-reinforced composite material layer. The fiber-reinforced composite material layer includes a carbon fiber layer 163 and a glass fiber layer 162. A metal electrode sheet 101 is embedded in the carbon fiber layer 163, and the metal electrode sheet 101 achieves surface contact coupling with the carbon fiber layer 163 (e.g., Figures 2 to 6 (As shown).

[0030] The bending neutral region refers to the area where the strain of the crash beam is zero or close to zero when subjected to bending load.

[0031] S2: Construct a segmented resistance measurement path based on two adjacent metal electrode plates 101 on the anti-collision beam 16; so that each segmented resistance measurement path corresponds to the mechanical response of different regions of the structure.

[0032] S3: Under the condition of applying a preset load, collect the resistance response data of each segmented resistance measurement path; The preset load is a quasi-static load, meaning it is applied in a quasi-static manner. Quasi-static means the load change rate is slow enough that, at any given resistance data acquisition moment, the measured structure is in or approximately in static equilibrium, with negligible inertial and damping forces. Specifically, this embodiment controls the loading rate to 0.01 mm / s and monitors the response values ​​of the segmented resistance measurement path in real time throughout the loading process. At this rate, the strain rate corresponding to structural deformation is less than 10. -4 s - ¹, which is much smaller than its dynamic deformation threshold, can therefore be considered a quasi-static load.

[0033] Steps S2 and S3 together constitute data acquisition.

[0034] S4: Before damage identification, the acquired resistance response data is normalized based on temperature parameters to map the resistance data to standard resistance data at a preset reference temperature (20℃~30℃, close to the laboratory standard environment); the standard resistance data serves as the sole input data for subsequent damage assessment; specifically, this includes the following steps: S41: Collects the core equilibrium temperature of the metal electrode 101; The core equilibrium temperature of the current structure can be obtained by utilizing the contact resistance characteristics between the pre-embedded metal electrode sheet 101 and the carbon fiber layer 163, or by using an external sensor.

[0035] The core equilibrium temperature refers to the temperature value collected by the metal electrode plate 101 located in the bending neutral region of the anti-collision beam 16. Since the metal electrode plate 101 is located at the physical reference point with the minimum strain response and is in a symmetrical position in terms of temperature response, its temperature measurement value is minimally affected by local strain and thermal gradient interference, and can be used as a reference temperature to characterize the overall thermal state of the structure for subsequent temperature normalization mapping.

[0036] S42: Differential calculation is performed using two segmented resistance measurement paths symmetrically arranged on both sides of the bending neutral region of the anti-collision beam 16 to eliminate local temperature and strain coupling interference; specifically, the following steps are included.

[0037] S421: Preprocess the resistance response data collected in step S3. Collect resistance data under static conditions (i.e., data during periods when the load is zero) continuously at a sampling frequency of 10-1000Hz within a time window of 1-30s. Calculate the average value of the current resistance data as the instantaneous zero reference value and subtract it from the subsequent measurement data to eliminate the influence of circuit drift and initial residual strain of the structure.

[0038] The 1-30s time window is specifically a window with a length between 1 and 30 seconds, immediately preceding the start of loading.

[0039] Preferably, before applying the quasi-static load, resistance data under static conditions are continuously collected at a sampling frequency of 100Hz; all data within the last 5 seconds before the start of loading are taken, the median is calculated as the instantaneous zero-position reference value, and subtracted from the subsequent measurement data; the instantaneous zero-position reference value is used to characterize the electrical steady-state reference value of the current structure under short-term static conditions before applying the quasi-static load; the instantaneous zero-position reference value is used to eliminate transient noise and local disturbances during the sampling process, and the resistance data after subtracting the instantaneous zero-position reference value in this step is used as the input reference for the standard state mapping process in step S43.

[0040] Strain coupling interference refers to the change in resistance caused by structural deformation under load through the piezoresistive effect. This change is superimposed on the resistance drift caused by temperature, resulting in the measured resistance signal containing both strain information and temperature noise. The temperature normalization process in this step aims to eliminate the influence of temperature on resistance, so that the standard resistance data only reflects the strain information related to the mechanical state of the structure, thereby decoupling the coupling interference between temperature and strain.

[0041] S422: Standard resistance data based on S421 self-calibration Calculate its relationship with birth fingerprints The relative offset; this offset is used as the initial damage weight and is included in the interface debonding determination operator in subsequent step S5 with a fixed bias. And the calculation of the material fracture determination operator δ; The offset is subtracted from the originally measured interface debonding damage judgment operator and the step offset of the reference resistance to obtain the compensated effective value. The compensated effective value is then compared with its respective preset threshold. The purpose of introducing this offset is to reduce the resistance response of the current structure to its factory health status reference, eliminate the baseline drift caused by individual manufacturing errors, contact resistance differences and non-damage factors, so that subsequent judgments only focus on the true damage increment relative to the baseline, effectively avoiding false alarms.

[0042] S423: Utilizing two segmented resistance measurement paths symmetrically set on both sides of the physical reference point C, namely segment AC and segment BC, differential calculation is performed: ; In the formula: ΔR grad For differential operational resistors, The resistance value of the AC segment resistance measurement path. The resistance value of the resistance measurement path for segment BC.

[0043] By using differential operations to cancel out the linear temperature gradient interference caused by localized vehicle heating (such as heat radiation from the engine compartment), the gradient temperature difference in the environmental dimension is eliminated. When the resistance value of the AC segment is measured... Resistance value of the resistance measurement path of segment BC If the path deviation is greater than 5%, it is determined that there is local damage in the area; when When the value is >1.05, damage is determined to exist on the BC segment side; when When the value is less than 0.95, damage is determined to exist on the AC segment side.

[0044] S43: Based on the acquired core equilibrium temperature, the acquired resistance is mapped to the standard reference temperature (25℃) using a second-order thermal sensitivity model. The mapping formula is as follows: ; in: For standard resistance data, To collect resistance, α、β For the pre-calibrated first and second order coefficients of thermal sensitivity, To collect the core equilibrium temperature, T ref Birth fingerprints Standard reference temperature during data collection.

[0045] The standard resistance data is compared with the birth fingerprint pre-stored in step S1. A comparison is performed to execute a determination; when the standard resistance data is relative to the birth fingerprint... When the deviation exceeds the preset tolerance range (±2%~±8%), the current environment or state is determined to not meet the evaluation conditions, and the health assessment process is terminated.

[0046] S5: Based on the standard resistance data preprocessed in step S4, the damage type is distinguished according to the electrical response pattern formed by the difference in response sensitivity of each segmented resistance measurement path to the damage type; among them: when the resistance curve with load changes with energy dissipation characteristics, it is determined to be interface damage; when the resistance shows a permanent step change after unloading, it is determined to be material fracture. The energy dissipation characteristics of the resistance-load curve are quantified by calculating the hysteresis area enclosed by the loading and unloading paths. This hysteresis area serves as the operator for determining interfacial debonding damage. It is obtained by numerical integration of discrete sampling points along the loading and unloading paths; when When the value exceeds the preset interface dissipation threshold, it is determined that the mechanical anchoring point between the metal layer 161 and the fiber-reinforced composite material layer is loose or microscopically debonded. Among them, the interface debonding damage determination operator The calculation formula is: ; In the formula: is the interface debonding damage determination operator (energy dissipation index), with units of joules or dimensionless normalized values; ∮ represents the full-path integration over a complete loading and unloading process; R The resistance value is a real-time segmented value that varies with the load and is expressed in ohms (Ω). F The quasi-static excitation force is applied to the middle of the anti-collision beam, and the unit is Newton (N). dF Quasi-static excitation force F The differential.

[0047] Physically, the interface debonding damage determination operator This represents the hysteresis loss generated at the interface under cyclic loading. The larger the loss area, the more severe the micro-friction or debonding at the interface anchor points.

[0048] when When the interface dissipation threshold is reached, it is determined that the mechanical anchoring point between the metal layer 161 and the fiber-reinforced composite material layer has loosened or microscopically debonded. Interface dissipation threshold Pre-calibration is achieved through statistical analysis of healthy and damaged samples.

[0049] Interface dissipation threshold The following statistical methods were used to predetermine the data: separate healthy and damaged sample sets were obtained. Plot the receiver operating characteristic (ROC) curve, and select the value corresponding to the maximum Youden Index (J = sensitivity + specificity - 1). Value as The interface dissipation threshold is equivalent to the difference between healthy and damaged samples. The optimal segmentation boundary that minimizes the overlapping area in the distribution.

[0050] Material fracture damage is assessed by monitoring the step offset of the reference resistance after unloading. δ To determine the step offset of the reference resistor δ The calculation formula is: ; In the formula: The reference resistance step offset (residual resistance change operator) is used to quantify the permanent structural step increment caused by the fracture of the conductive network (carbon fiber bundle). The residual resistance value of the reference resistor after testing, after applying and removing the standard load; Reference resistor before testing; initial resistance value before applying load. This is performed under a fully unloaded state to eliminate the instantaneous contribution of elastic strain to the resistance; when δ Greater than the preset structural damage threshold δ th When the slope of the resistance-load relationship curve shows a step change, that is, when the resistance shows a permanent step change after unloading, it is determined to be brittle fracture or delamination damage of the fiber bundle.

[0051] Preset structural damage threshold δ th The threshold for structural damage was obtained through statistical analysis of the resistance response data of healthy structural samples and known damaged structural samples; a preset structural damage threshold was also included. δ th It can be dynamically adjusted according to the ambient temperature or the service status of the structure.

[0052] Acquire reference resistance step offset of healthy structural samples under fully unloaded state δ Obtain its statistical distribution interval; collect the reference resistance step offset of known damaged structure samples. δ Obtain its statistical distribution interval; preset structural damage threshold. δ th Defined as the split point corresponding to minimizing the overlap area between the two classes of sample distributions. This threshold serves as the discrimination criterion: when... δ ≥ δ th When this occurs, it is determined to be brittle fracture or delamination damage of the fiber bundle.

[0053] Since the resistance response is affected by external factors such as ambient temperature, service aging, and load history, the preset structural damage threshold... δ th It is not a fixed constant, but varies with the current ambient temperature. T A dynamically adjusted function. In a preferred embodiment, a piecewise linear correction model based on temperature is employed: ; In the formula: Current temperature T Structural damage threshold under certain conditions; Reference temperature The pre-calibrated structural damage threshold benchmark value is used; The sensitivity coefficient of the structural damage threshold to temperature was obtained through experimental calibration. T The current ambient temperature; The reference temperature is the ambient temperature during the initial calibration experiment.

[0054] This piecewise linear correction model based on temperature can eliminate the influence of temperature drift on the resistance criterion and achieve consistency in damage assessment under different environmental conditions.

[0055] The slope of the resistance-load curve is defined as: ; In the formula, k Let be the slope of the resistance versus load curve. For resistance integral, For load integral.

[0056] Under discrete sampling conditions, the slope between adjacent sampling points is expressed in difference form as follows: ; in, The slope between adjacent sampling points. and The first iThe load value and corresponding resistance value at each sampling point and The first i+1 The load value and corresponding resistance value of each sampling point.

[0057] To quantitatively determine whether a step change occurs in the resistance-load response curve, the concept of the rate of change of adjacent slopes is further introduced based on the above definition of slope: ; When the rate of change of adjacent slopes Exceeding the preset mutation threshold η th When the resistance response curve undergoes a step change in that range, it is determined that the resistance response curve has changed abruptly.

[0058] Preferred parameters: The mutation threshold η th The value range is 20%-50%, that is, when the rate of change of adjacent slopes... A step change is considered to have occurred when the percentage is greater than or equal to any selected threshold between 20% and 50%. Below 20%, normal measurement fluctuations are easily misjudged as a sudden change, while above 50%, a true step response may be missed. This threshold can be adjusted within the above range according to the resistance and load response sensitivity of the specific sensor, with a preferred threshold of 30%.

[0059] All damage assessments in this invention are based on an absolute and traceable benchmark, namely the "birth fingerprint" recorded at the time of manufacture of the anti-collision beam (16). Therefore, before performing any damage identification steps, the measured data must first be preprocessed using a standard state mapping based on a second-order thermal sensitivity model. This preprocessing is not a simple temperature compensation formula, but a mandatory data cleaning and benchmark alignment criterion. The second-order thermal sensitivity model is used to map the current temperature... T cur Measured resistance below R ( T cur Mapped to standard reference temperature T ref Standard resistance This data is compared with the birth fingerprint at the time of manufacture. They are in the same comparable benchmark state.

[0060] After completing the standard state mapping, With cloud storage Perform a consistency comparison. The result of this comparison serves as the threshold for all subsequent judgments. when and If the deviation is within the preset tolerance range: if the current environmental conditions and sensor status meet the evaluation requirements, the system allows the subsequent energy dimension (interface debonding identification) and structural dimension (material fracture identification) judgment process to proceed.

[0061] When the deviation exceeds the preset tolerance range, it indicates that the ambient temperature interference has exceeded the system's compensation capability limit, or that the sensor / measurement circuit has a self-test anomaly. In this case, to ensure the absolute rigor and reliability of the health assessment conclusion, the system will refuse to output any health assessment report and immediately terminate the entire assessment process.

[0062] The aforementioned threshold mechanism essentially defines the order of data cleaning and mechanism decoupling, ensuring that all input data used for damage assessment are accurate, consistent, and comparable, and preventing the behavior of bypassing this preprocessing criterion to directly make damage assessments.

[0063] like Figure 6 As shown, this invention evaluates the resistance variation curve with load under a fully healthy state (elastic stage). In its fully healthy state, the anti-collision beam 16 is in the elastic working stage, with good interfacial bonding between the metal layer 161 and the fiber-reinforced composite material layer, and a complete conductive network between the carbon fiber layer 163 and the metal electrode sheet 101. When a quasi-static load is applied, the resistance along the segmented resistance measurement path changes monotonically with increasing load; after the load is removed, the resistance returns along the loading path, and the loading curve and unloading curve basically coincide, with the hysteresis area approaching zero. After unloading, the resistance accurately recovers to the value captured at the time of manufacture. This indicates that the structure has not undergone plastic deformation or any form of damage.

[0064] like Figure 7 As shown, the resistance of the interface under debonding damage state is evaluated by the present invention as a function of load. When microscopic debonding or loosening of the anchor points occurs at the interface between the metal layer 161 and the fiber-reinforced composite layer, energy dissipation occurs under cyclic loading. The loading and unloading paths no longer coincide, forming a distinct hysteresis loop, and the hysteresis area... The resistance increases significantly. The physical significance of this hysteresis area lies in characterizing the energy dissipated by micro-friction or debonding propagation at the interface. Although energy dissipation occurs during loading, the resistance can still recover to its initial value after unloading. The presence of the carbon fiber layer 163 nearby indicates that the conductive network between the carbon fiber layer 163 and the metal electrode sheet 101 has not been permanently damaged, and the damage is mainly limited to the interface layer.

[0065] like Figure 8 As shown, the present invention evaluates the resistance as a function of load under fiber fracture damage conditions. When the carbon fiber layer 163 undergoes brittle fracture or interlayer delamination, the conductive pathway is irreversibly disrupted. During loading, when the load reaches a certain critical value (i.e., the "fracture point"), the resistance exhibits a step-like abrupt change, and the curve shows a significant irreversible step-like increase. ΔR The physical significance of this step increment lies in characterizing the number of conductive channels lost due to fiber breakage in the conductive network between the carbon fiber layer 163 and the metal electrode sheet 101. After unloading, the resistance cannot be restored to the initial fingerprint value. Instead, it remains at a high resistance level, generating a permanent residual increment. This permanent step increment is the residual resistance operator δ defined in this invention.

[0066] like Figure 9 As shown, a heterogeneous hybrid anti-collision beam health evaluation system includes a sensor unit 10, an excitation unit 11, a data acquisition unit 12, a processing unit 13, a storage unit 14, and a communication unit 15. The sensor unit 10 includes three metal electrode plates 101 disposed within the anti-collision beam 16, used to sense the resistance and temperature signals of each segmented resistance measurement path. A segmented resistance measurement path is formed between two adjacent metal electrode plates 101. The excitation unit 11 applies a preset quasi-static load to the anti-collision beam 16. The data acquisition unit 12 is connected to the sensor unit 10 and is used to acquire resistance response data and temperature data for each segmented resistance measurement path. The processing unit 13 is connected to both the data acquisition unit 12 and the excitation unit 11, used to control the excitation unit 11 to apply the quasi-static load, and to receive the resistance response data and temperature data acquired by the data acquisition unit 12. It is also used to perform temperature-based normalization processing, standard resistance analysis, and analysis of birth fingerprints. Comparison and judgment, dynamic benchmark drift compensation, and interface debonding damage judgment operators The calculation of the material fracture damage determination operator δ and the generation of the health report (steps S4 and S5); the storage unit 14 is connected to the processing unit 13 and is used to store birth fingerprint data and historical service records; the communication unit 15 is connected to the processing unit 13 and is used to interact with the cloud database, report the health report generated by the processing unit 13 to the cloud database, and update the part service records.

[0067] In heterogeneous hybrid structures, the electrical resistance of aluminum alloy and carbon fiber composite materials fluctuates drastically and nonlinearly with temperature. The magnitude of this temperature drift effect far exceeds the electrical signal generated by early damage. This invention does not simply compensate by subtracting the temperature difference value, but rather constructs a unified "standard state space." Through a second-order thermal sensitivity matrix, it projects measured resistance data under different spatiotemporal and temperature conditions onto the original manufacturing fingerprint of the crash beam 16. The same baseline conditions enable cross-temporal and spatial baseline alignment and accurate extraction of damage signals.

[0068] Before performing damage assessment, the acquired resistance response data must first undergo temperature-based normalization, which involves mapping the acquired resistance to a standard reference temperature using a second-order thermal sensitivity model. This normalization is not a simple calculation formula, but a preprocessing criterion whose function is to uniformly map measured resistance data under different temperature conditions to the standard resistance space at the standard reference temperature.

[0069] Normalized standard resistance data is the only valid input for all subsequent damage assessment steps. In other words, data that has not been cleaned using this preprocessing criterion must not enter the assessment process for the energy dimension (interface debonding identification) and the structural dimension (material fracture identification). This strict definition of the order technically separates the "data cleaning" and "mechanism decoupling" stages, ensuring that all damage feature extractions are based on a unified and comparable benchmark.

[0070] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0071] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for evaluating the health of heterogeneous hybrid anti-collision beams, characterized in that: Includes the following steps: S1: At least three metal electrode plates (101) are provided inside the anti-collision beam (16). The at least three metal electrode plates (101) are arranged along the length direction of the anti-collision beam (16). At least one metal electrode plate (101) is located in the bending neutral region of the anti-collision beam (16) and serves as a physical reference point with minimum strain response and symmetrical temperature response. The remaining metal electrode plates (101) are symmetrically arranged on both sides of the metal electrode plates (101) in the bending neutral region. The two metal electrode plates (101) located at both ends are arranged close to the two ends of the anti-collision beam (16) to capture local strain fluctuations. The initial resistance data of each metal electrode plate (101) is collected under factory conditions and standard reference temperature as the unique birth fingerprint of the anti-collision beam (16). And store it; The anti-collision beam (16) includes a metal layer (161) and a fiber-reinforced composite material layer. The fiber-reinforced composite material layer includes a glass fiber layer (162) and a carbon fiber layer (163). A metal electrode sheet (101) is embedded in the carbon fiber layer (163) and achieves surface contact coupling with the carbon fiber layer (163) through the metal electrode sheet (101). S2: Construct a segmented resistance measurement path based on two adjacent metal electrode plates (101) on the anti-collision beam (16); S3: Under the condition of applying a preset load, collect the resistance response data of each segmented resistance measurement path; S4: Perform temperature-based normalization processing on the collected resistance response data to map the resistance data to standard resistance data at a preset reference temperature; S5: Based on the standard resistance data preprocessed in step S4, the damage type is distinguished according to the electrical response pattern formed by the difference in response sensitivity of each segmented resistance measurement path to the damage type; among them: when the resistance curve with load changes with energy dissipation characteristics, it is determined to be interface damage; when the resistance shows a permanent step change after unloading, it is determined to be material fracture.

2. The method for evaluating the health of heterogeneous hybrid anti-collision beams according to claim 1, characterized in that: In step S4, the acquired resistance response data is normalized based on temperature parameters to compensate for temperature and strain coupling interference, including the following steps: S41: Collect the core equilibrium temperature of the metal electrode sheet (101); S42: Differential calculation is performed using two segmented resistance measurement paths symmetrically set on both sides of the bending neutral region of the anti-collision beam (16) to eliminate local temperature gradient interference; S43: The acquisition resistance is mapped to a standard reference temperature by using the core equilibrium temperature and a second-order thermal sensitivity model. The mapping formula is as follows: ； in: For standard resistance data, To collect resistance, α、β For the pre-calibrated first and second order coefficients of thermal sensitivity, To collect the core equilibrium temperature, T ref Birth fingerprints Standard reference temperature during data collection.

3. The method for evaluating the health of heterogeneous hybrid anti-collision beams according to claim 2, characterized in that: In step S42, the specific steps for eliminating local temperature gradient interference include: S421: Preprocess the resistance response data collected in step S3. Collect resistance data under static conditions continuously at a sampling frequency of 10-1000Hz within a time window of 1-30s. Calculate the average value of the current resistance data as the instantaneous zero reference value and deduct it from the subsequent measurement data. S422: Standard resistance data based on S421 self-calibration Calculate its relationship with birth fingerprints The relative offset; this offset is used as the initial damage weight and is included in the interface debonding judgment and material fracture judgment in step S5 with a fixed bias. S423: Utilizing two segmented resistance measurement paths symmetrically set on both sides of the physical reference point C, namely segment AC and segment BC, differential calculation is performed: ； In the formula: ΔR grad For differential operational resistors, The resistance value of the AC segment resistance measurement path. The resistance value of the resistance measurement path for segment BC.

4. The method for evaluating the health of heterogeneous hybrid anti-collision beams according to claim 3, characterized in that: In step S4, the standard resistance data is compared with the birth fingerprint pre-stored in step S1. A comparison is performed to execute a determination; when the standard resistance data is relative to the birth fingerprint... When the deviation exceeds the preset tolerance range, the current environment or state is determined to not meet the evaluation conditions, and the health assessment process is terminated.

5. The method for evaluating the health of heterogeneous hybrid anti-collision beams according to claim 1, characterized in that: In step S5, the energy dissipation characteristics of the resistance-load variation curve are quantified by calculating the hysteresis area enclosed by the loading and unloading paths. This hysteresis area serves as the interface debonding damage determination operator. It is obtained by numerical integration of discrete sampling points along the loading and unloading paths; when When the value exceeds the preset interface dissipation threshold, it is determined that the mechanical anchoring point between the metal layer (161) and the fiber-reinforced composite material layer is loose or microscopically debonded.

6. The method for evaluating the health of heterogeneous hybrid anti-collision beams according to claim 5, characterized in that: Interface debonding damage determination operator The calculation formula is: ； In the formula: This is the operator for determining interface debonding damage; ∮ represents full path integration over a complete loading and unloading process. R The resistance value is a real-time segment that varies with the load. F As a quasi-static load excitation force, it is applied to the middle of the anti-collision beam (16). dF Quasi-static excitation force F The differential; When the interface debonding damage determination operator When the damage exceeds the preset structural damage threshold, it is determined that the mechanical anchoring point between the metal layer (161) and the fiber-reinforced composite material layer is loose or microscopically debonded.

7. The method for evaluating the health of heterogeneous hybrid anti-collision beams according to claim 1, characterized in that: In step S5, material fracture damage is assessed by monitoring the step offset of the reference resistance after unloading. δ To determine the step offset of the reference resistor δ The calculation formula is: ； In the formula: This is the reference resistance step offset, used to quantify the permanent structural step increment caused by the fracture of the conductive network (carbon fiber bundle); The residual resistance value of the reference resistor after testing, after applying and removing the standard load; Reference resistor before testing; initial resistance value before applying load. This is performed under a fully unloaded state to eliminate the instantaneous contribution of elastic strain to the resistance; When the reference resistor step offset δ When the damage exceeds the preset structural damage threshold and the slope of the resistance-load relationship curve shows a step change, it is determined to be brittle fracture or delamination damage of the fiber bundle.

8. A health evaluation system for heterogeneous hybrid anti-collision beams, used in the method of any one of claims 1 to 7, characterized in that: The system includes a sensor unit (10), an excitation unit (11), a data acquisition unit (12), a processing unit (13), a storage unit (14), and a communication unit (15). The sensor unit (10) includes at least three metal electrode plates (101) disposed within the anti-collision beam (16) to sense the resistance and temperature signals of each segmented resistance measurement path. A segmented resistance measurement path is formed between two adjacent metal electrode plates (101). The excitation unit (11) is used to apply a preset quasi-static load to the anti-collision beam (16). The data acquisition unit (12) is connected to the sensor unit (10) and is used to acquire the resistance response data and temperature data of each segmented resistance measurement path. The processing unit (13) is connected to the data acquisition unit (10) and the data acquisition unit (12). The unit (12) is connected to the excitation unit (11) and is used to control the excitation unit (11) to apply a quasi-static load and receive the resistance response data and temperature data collected by the acquisition unit (12). It is also used to perform normalization processing based on temperature parameters, comparison and judgment of standard resistance and birth fingerprint, dynamic reference drift compensation, interface debonding damage judgment, material fracture damage judgment and health report generation. The storage unit (14) is connected to the processing unit (13) and is used to store birth fingerprint data and historical service records. The communication unit (15) is connected to the processing unit (13) and is used to interact with the cloud database, report the health report generated by the processing unit (13) to the cloud database, and update the part service records.

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