Train body coating structure testing method, device, equipment and medium

Abstract

The invention provides a test method, device and equipment for a train body coating structure and a medium, and the method comprises the steps: obtaining acceleration data detected by at least one sensor in a train operation process; based on the mathematical model of the vehicle body coating structure, determining a mapping relation between the vehicle body coating structure and a load; reversely deducing a test spectrum based on the acceleration data and the mapping relation; and the test spectrum is transmitted to a vibration table, so that when the vibration table vibrates according to the test spectrum, fatigue test is performed on the to-be-tested vehicle body coating structure. According to the method, the test spectrum which can be applied to the vibration table can be obtained, so that the fatigue test is performed on the vehicle body coating structure under the condition that the load of a real driving scene is restored.

Description

Technical Field

[0001] This application relates to the field of fatigue testing of high-speed train body covering structures, and more specifically, to a testing method, apparatus, equipment, and medium for train body covering structures. Background Technology

[0002] With the continuous increase in the operating speed of high-speed trains, higher requirements are placed on the aerodynamic performance of the trains. In order to reduce air resistance and protect the equipment under the train, a covering structure is designed and installed in the bogie area under the high-speed train. The covering structure of the high-speed train (including skirts, floor plates, etc.) is simultaneously subjected to the coupled effects of aerodynamic loads and vibration loads during operation, making it extremely susceptible to vibration fatigue failure. Vibration fatigue cracking often occurs in the connecting parts inside the equipment compartment of the EMU, which seriously threatens the safety of train operation.

[0003] Currently, traditional airtight fatigue testing benches (also known as vibration tables) are mainly used to measure enclosed structures and cannot directly apply aerodynamic loads to non-enclosed structures such as the body covering structure of high-speed trains. Therefore, the working method of vibration tables in the existing technology cannot accurately simulate the stress state under actual service conditions.

[0004] Therefore, there is a need to provide a solution for testing the body covering structure of a train. Summary of the Invention

[0005] In view of this, embodiments of this application provide a testing method, apparatus, equipment, and medium for testing the fatigue performance of train body covering structures.

[0006] In a first aspect, embodiments of this application provide a testing method for a train body covering structure, the method comprising: Acquire acceleration data detected by at least one sensor during train operation; the at least one sensor is installed at a preset stress point on the vehicle body covering structure; Based on the mathematical model of the vehicle body covering structure, the mapping relationship between the vehicle body covering structure and the load is determined. Based on the acceleration data and the mapping relationship, the test spectrum is derived. The test spectrum is transmitted to the vibration table, so that when the vibration table vibrates according to the test spectrum, fatigue testing is performed on the vehicle body covering structure to be tested.

[0007] In one feasible implementation, based on the mathematical model of the vehicle body covering structure, the mapping relationship between the vehicle body covering structure and the load is determined, including: Construct a finite element model of the vehicle body covering structure; An excitation with a preset frequency is applied to the finite element model to obtain a frequency response function matrix; the frequency response function matrix is ​​used to characterize the mapping relationship between the vehicle body covering structure and the load.

[0008] In one feasible implementation, the method further includes: Based on the acceleration data, the power spectral density (PSD) during train operation is generated. Based on the acceleration data and the mapping relationship, the test spectrum is derived, including: Based on the power spectral density (PSD) and the frequency response function matrix, the excitation spectrum (PSD) is calculated by inversion. Based on the damage equivalence principle, the excitation spectrum PSD is converted into a time-compressed test spectrum.

[0009] In a feasible implementation, based on the damage equivalence principle, the excitation spectrum PSD is converted into a time-compressed test spectrum, including: Extract the excitation PSD values ​​corresponding to the preset frequency band points to generate a simplified excitation spectrum PSD; Based on the damage equivalence principle, the simplified excitation spectrum PSD is transformed into a time-compressed test spectrum.

[0010] In one feasible implementation, the preset stress point is located at the connection of the train body covering structure, and the connection includes at least one of the following locations: The welds of the skirt support frame, the welds of the skirt base frame mounting seat, the welds of the central covering hanger, and the connection area of ​​the central base plate.

[0011] In one feasible implementation, an excitation containing a preset frequency is applied to the finite element model to obtain a frequency response function matrix, including: Determine the constraint positions in the finite element model corresponding to the preset stress points; A unit white noise acceleration spectrum in the X, Y, and Z axes is applied at the constrained position; The frequency response function matrix is ​​obtained by regularizing the ill-conditioned matrix through truncated singular value decomposition (TSVD).

[0012] In a feasible implementation, based on the damage equivalence principle, the simplified excitation spectrum PSD is converted into a time-compressed test spectrum, including: For the simplified excitation spectrum PSD, the limit response spectrum (ERS) and fatigue damage spectrum (FDS) of the vehicle body covering structure under all working conditions throughout the entire life cycle are calculated. The ERS and FDS are summed separately to obtain the total target ERS and the total target FDS; Based on the total target damage amount and the equivalent test time, the target test spectrum can be deduced. In response to determining that the ERS of the target test spectrum is greater than the total target ERS and that the frequency domain characteristics are consistent with the PSD of the excitation spectrum, the target test spectrum is determined as the time-compressed test spectrum.

[0013] Secondly, embodiments of this application also provide a testing device for train body covering structures, the device comprising: The data acquisition module is used to acquire acceleration data detected by at least one sensor during train operation; the at least one sensor is set at a preset stress point on the vehicle body covering structure. The relationship determination module is used to determine the mapping relationship between the vehicle body covering structure and the load based on the mathematical model of the vehicle body covering structure; The reverse deduction module is used to deduce the test spectrum based on the acceleration data and the mapping relationship; The testing module is used to transmit the test spectrum to the vibration table, so that when the vibration table vibrates according to the test spectrum, fatigue testing is performed on the vehicle body covering structure to be tested.

[0014] In one feasible implementation, the relationship determination module is used to determine the mapping relationship between the vehicle body covering structure and the load based on the mathematical model of the vehicle body covering structure, for the following purposes: Construct a finite element model of the vehicle body covering structure; An excitation with a preset frequency is applied to the finite element model to obtain a frequency response function matrix; the frequency response function matrix is ​​used to characterize the mapping relationship between the vehicle body covering structure and the load.

[0015] In one feasible implementation, the device further includes: The first generation module is used to generate the power spectral density (PSD) during train operation based on the acceleration data. The reverse deduction module is used to deduce the test spectrum based on the acceleration data and the mapping relationship, including: Based on the power spectral density (PSD) and the frequency response function matrix, the excitation spectrum (PSD) is calculated by inversion. Based on the damage equivalence principle, the excitation spectrum PSD is converted into a time-compressed test spectrum.

[0016] In one feasible implementation, the back-calculation module is used to convert the excitation spectrum PSD into a time-compressed test spectrum based on the damage equivalence principle, including: Extract the excitation PSD values ​​corresponding to the preset frequency band points to generate a simplified excitation spectrum PSD; Based on the damage equivalence principle, the simplified excitation spectrum PSD is transformed into a time-compressed test spectrum.

[0017] In one feasible implementation, the preset stress point is located at the connection of the train body covering structure, and the connection includes at least one of the following locations: The welds of the skirt support frame, the welds of the skirt base frame mounting seat, the welds of the central covering hanger, and the connection area of ​​the central base plate.

[0018] In one feasible implementation, the relationship determination module is used to apply an excitation containing a preset frequency to the finite element model to obtain a frequency response function matrix, including: Determine the constraint positions in the finite element model corresponding to the preset stress points; A unit white noise acceleration spectrum in the X, Y, and Z axes is applied at the constrained position; The frequency response function matrix is ​​obtained by regularizing the ill-conditioned matrix through truncated singular value decomposition (TSVD).

[0019] In one feasible implementation, the back-calculation module is used to convert the simplified excitation spectrum PSD into a time-compressed test spectrum based on the damage equivalence principle, including: For the simplified excitation spectrum PSD, the limit response spectrum (ERS) and fatigue damage spectrum (FDS) of the vehicle body covering structure under all working conditions throughout the entire life cycle are calculated. The ERS and FDS are summed separately to obtain the total target ERS and the total target FDS; Based on the total target damage amount and the equivalent test time, the target test spectrum can be deduced. In response to determining that the ERS of the target test spectrum is greater than the total target ERS and that the frequency domain characteristics are consistent with the PSD of the excitation spectrum, the target test spectrum is determined as the time-compressed test spectrum.

[0020] Thirdly, embodiments of this application also provide an electronic device, including: a processor, a storage medium, and a bus, wherein the storage medium stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the storage medium via the bus, and the processor executes the machine-readable instructions to perform the steps of the test method as described in any one of the first aspects.

[0021] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the test method as described in any one of the first aspects.

[0022] This application provides a testing method, apparatus, equipment, and medium for a train body covering structure. Considering that trains are affected by airflow and vibration (aerodynamic loads and vibration loads) during operation, the durability of the body covering structure is mainly related to the loads (aerodynamic loads and vibration loads). Based on this, by setting sensors at preset stress points on the train body covering structure, the actual acceleration data at these preset stress points detected during train operation can be obtained. Thus, using the mathematical model of the body covering structure, the location of the preset stress points on the body covering structure, and the acceleration data detected by the sensors, the mapping relationship between the body covering structure and the load (under real operating conditions) can be derived. Then, based on the mapping relationship between the body covering structure and the load, the required test spectrum (PSD) can be derived.

[0023] In this way, by applying a test spectrum to the vibration table, the fatigue damage and ultimate response of the vehicle body covering structure during its entire life cycle can be equivalently reproduced in the laboratory.

[0024] In summary, the technical solution provided by the embodiments of this application can comprehensively consider the influence of aerodynamic loads and vibration loads on the cladding structure, and more accurately evaluate the fatigue strength of the cladding structure, providing an effective means for bench testing of non-enclosed structures such as vehicle body cladding that are greatly affected by aerodynamic loads.

[0025] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 A flowchart illustrating a test method for a train body covering structure provided in an embodiment of this application is shown.

[0028] Figure 2 A structural diagram of the vehicle body covering structure provided in the embodiments of this application is shown.

[0029] Figure 3 A diagram showing the location of the preset stress points provided in the embodiments of this application is illustrated.

[0030] Figure 4 A flowchart illustrating another test method for a train body covering structure provided in an embodiment of this application is shown.

[0031] Figure 5 A schematic diagram of a test device for a train body covering structure provided in an embodiment of this application is shown.

[0032] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0034] With technological advancements and the continuous increase in operating speeds of trains with body covering structures, such as high-speed trains, bullet trains, and regular trains, higher demands are placed on their aerodynamic performance. To reduce air resistance and protect undercarriage equipment, covering structures are designed and installed in the bogie area under high-speed trains.

[0035] The aerodynamic loads borne by the car body cladding structure are becoming increasingly complex and severe. During high-speed train operation, special conditions such as strong winds and tunnel intersections cause drastic fluctuations in the aerodynamic pressure on the cladding structure surface. These fluctuations not only exhibit high-frequency characteristics but also show significant spatial non-uniformity. Existing vibration table tests struggle to accurately simulate such complex and variable aerodynamic load environments, making it impossible to accurately assess the mechanical properties and fatigue life of the cladding structure under actual service conditions. As a crucial component of the train, the reliability of the car body cladding structure directly impacts operational safety. Fatigue failure, loosening, or detachment of the cladding structure can pose a serious threat to train operation, such as affecting aerodynamic performance, causing additional vibration and noise, and even endangering the safety of the train and passengers.

[0036] Currently, traditional airtight fatigue testing benches (also known as vibration tables) are mainly used to measure enclosed structures and cannot directly apply aerodynamic loads to non-enclosed structures such as the body covering structure of high-speed trains. Therefore, the working method of vibration tables in the existing technology cannot accurately simulate the stress state under actual service conditions.

[0037] The core of this problem is that it is impossible to find a power spectral density (PSD) that, when directly input into the vibration table, allows the vibration table to simulate the aerodynamic and vibration loads experienced by the train in its actual operating environment.

[0038] Based on this, embodiments of this application provide a testing method, apparatus, equipment, and medium for train body covering structures. By measuring the acceleration data of the body covering structure during actual train operation, a mathematical model of the body covering structure can be used to obtain the mapping relationship between the body covering structure and loads (aerodynamic loads and / or vibration loads) under real operating conditions. Then, based on this mapping relationship, the "force" to be applied to the body covering structure can be deduced. This "force" involves complex time series or frequency distributions, therefore it needs to be described as a test spectrum that the vibration table can understand. In this way, after receiving the test spectrum, the vibration table can apply fatigue testing to the body covering structure in the expected manner. This test result can reflect the durability of the train during actual operation. The following is a description through embodiments.

[0039] To facilitate understanding of this embodiment, a test method for a train body covering structure disclosed in this application will first be described in detail. For example... Figure 1 The flowchart of the test method for the train body covering structure shown includes the following steps: Step 101: Obtain acceleration data detected by at least one sensor during train operation; the at least one sensor is set at a preset stress point on the vehicle body covering structure.

[0040] Preset stress points are typically the most vulnerable locations in the train body cladding structure. When considering the fatigue strength of the cladding structure, special attention should be paid to fatigue damage caused by resonance due to aerodynamic pressure differential. Furthermore, fatigue assessment results from the quasi-static method indicate that welds are more prone to fatigue failure than the base material; therefore, the location of welds in the cladding structure should be given particular attention.

[0041] Therefore, in a feasible embodiment, the preset stress point is set at the connection of the train body covering structure, and the connection includes at least one of the following locations: The welds of the skirt support frame, the welds of the skirt base frame mounting seat, the welds of the central covering hanger, and the connection area of ​​the central base plate.

[0042] Figure 2 A structural diagram of the vehicle body covering structure provided in an embodiment of this application is shown. Figure 2 As shown, several common hazardous locations (prone to fatigue in the body cladding structure) are identified, including: the skirt support weld, the skirt underframe mounting weld, the central cladding hanger weld, and the location of the central floor plate connection area. At this point, one or more preset stress points can be selected at each location.

[0043] Alternatively, constraint locations can be selected according to the following principles: they should reflect the response information of the vehicle body cladding structure as much as possible, while avoiding symmetrical points on the vehicle body cladding structure. In this case, the locations of each preset stress point can be obtained based on experience and simulation verification. For example, ... Figure 3 As shown, three locations (A5, A7, A8) close to the dangerous weld are selected from multiple locations (A1, A2, A3, A4, A5, A6, A7, A8) as preset stress points equivalent to the triaxial random vibration response.

[0044] For example, the sensor set at the preset stress point can be a triaxial accelerometer, which can collect acceleration (response) data at each preset stress point during train operation.

[0045] Step 102: Based on the mathematical model of the vehicle body covering structure, determine the mapping relationship between the vehicle body covering structure and the load.

[0046] By building a mathematical model of the vehicle body cladding structure in the software and inputting the acceleration data corresponding to each preset stress point on the vehicle body cladding structure into the mathematical model, the mapping relationship between the vehicle body cladding structure and the load can be obtained from the mathematical model. This mapping relationship can reflect the dynamic behavior and stress state of the vehicle body cladding structure under the combined action of aerodynamic and vibration loads.

[0047] For example, based on the mathematical model of the vehicle body covering structure, the mapping relationship between the vehicle body covering structure and the load is determined, including: A finite element model of the vehicle body covering structure is constructed. An excitation containing a preset frequency is applied to the finite element model to obtain a frequency response function matrix; the frequency response function matrix is ​​used to characterize the mapping relationship between the vehicle body covering structure and the load.

[0048] First, a finite element model of the vehicle body cladding structure is constructed. By applying a preset frequency excitation (e.g., unit white noise excitation) to this finite element model within the frequency band of interest, its frequency response function matrix can be calculated and obtained. This matrix theoretically characterizes the mapping relationship between the load input and the dynamic response of the structure (such as acceleration and stress).

[0049] However, to ensure the consistency between the theoretical model and the physical entity (i.e., the body covering structure during actual train operation), it is necessary to verify and correct the finite element model using acceleration data collected at preset stress points during actual train tests. This process aims to adjust model parameters such as boundary conditions and connection stiffness so that the frequency response function calculated by the model closely matches the measured data.

[0050] Ultimately, the validated high-fidelity finite element model and its frequency response function matrix constitute the reliable "mapping relationship" we require. Using this mapping relationship, we can quantify and invert or predict the key mechanical states, such as stress, strain, and vibration levels, of critical components of the vehicle body cladding structure under arbitrary combinations of aerodynamic and vibration loads.

[0051] Step 103: Based on the acceleration data and the mapping relationship, the test spectrum is deduced.

[0052] Given the known mapping relationship (result) between the vehicle body covering structure and the load, we need to deduce the "cause". This cause is the input load used to drive the vibration table, so as to realize the restoration of the train's real operating environment and thus complete the fatigue test.

[0053] In other words, the laboratory reproduction of the real operating environment is achieved through a reverse engineering process. The core of this method lies in using the measured structural response throughout the train's entire life cycle as the target, and then using verified mapping relationships to deduce the input load that the shaking table must apply. This deduced load time-domain signal or power spectral density serves as the control benchmark for driving the shaking table to accurately reproduce the actual stress state of the structure. Subsequently, based on the deduced load, the final test spectrum is generated.

[0054] In one feasible implementation, the method further includes: Based on the acceleration data, the power spectral density (PSD) during train operation is generated.

[0055] At this point, the PSD spectrum can be obtained through Fast Fourier Transform.

[0056] For example, taking stress point one as a preset stress point, the time-domain signals of vibration acceleration along the X, Y, and Z axes at stress point one are processed to remove zero drift and outliers. The acceleration power spectral density obtained by fast Fourier transform is used as the target acceleration response spectrum. The acceleration response at stress point one is mainly in the Y and Z directions, while the power spectral density value in the X direction is relatively small, with frequencies mainly concentrated between 40 and 100 Hz. Therefore, data above 120 Hz can be truncated.

[0057] At this point, based on the acceleration data and the mapping relationship, the test spectrum is deduced, including: Based on the power spectral density (PSD) and the frequency response function matrix, the excitation spectrum (PSD) is calculated by inversion. Based on the damage equivalence principle, the excitation spectrum (PSD) is converted into a time-compressed test spectrum.

[0058] The PSD (also known as the response PSD) generated from acceleration data accurately describes the frequency distribution of vibration energy in the vehicle structure under real-world operating conditions. The core "reverse solution" then unfolds: using the frequency response function matrix characterizing the system, we perform mathematical inversion calculations to extract the root excitation PSD from this response PSD. The excitation PSD describes the distribution of vibration energy across different frequency components of the random excitation force acting on the structure.

[0059] It is important to note that the excitation PSD obtained from the inversion describes the actual load environment experienced by the train throughout its entire life cycle. Directly using this spectrum for reproduction testing is impractical because the time span could be decades, making the testing costs unacceptable. Therefore, the "damage equivalence principle" must be introduced as the core basis for accelerated testing. This principle states that by scientifically increasing the severity of the vibration load, the fatigue damage accumulated by the structure during long-term real-world operation can be equivalently reproduced within a very short testing time.

[0060] In other words, by utilizing the damage equivalence principle, the long real load spectrum (excitation PSD) is compressed into a short-term, high-intensity but damage-equivalent executable test spectrum.

[0061] In one feasible implementation, an excitation containing a preset frequency is applied to the finite element model to obtain a frequency response function matrix, including: Determine the constraint positions in the finite element model corresponding to the preset stress points. Apply unit white noise acceleration spectra in the X, Y, and Z axes at the constraint positions; obtain the frequency response function matrix by regularizing the ill-conditioned matrix through truncated singular value decomposition (TSVD).

[0062] Taking the constraint position corresponding to one of the preset stress points (stress point one) as an example, the unit white noise acceleration spectrum (amplitude 1g, bandwidth 1-120Hz) along the X, Y, and Z axes is applied at this constraint position.

[0063] In the case of triaxial random vibration, if loads are applied synchronously along the X, Y, and Z axes and the excitations are independent of each other, assuming... The acceleration response power spectrum generated by L-axis excitation in the R-axis direction. The power spectrum of acceleration excitation along the x, y, and z axes. Let be the frequency response function between the l-axis excitation and the r-axis response. The superscript * indicates the complex conjugate. Therefore, the power spectrum of the three axial acceleration responses at a stress point is: When a unit white noise acceleration excitation spectrum is applied simultaneously along three axes, assuming To determine the acceleration response power spectrum along the R direction when a unit white noise excitation is applied along the L axis, the relationship between the acceleration response power spectra along the three axes of stress point one and the excitation is as follows: The total acceleration response power spectrum along the three axes of stress point one is then: Represented in matrix form as follows:

[0064] Given the acceleration response power spectra along the three axes (hereinafter referred to as the target response spectra), the load matrix to be identified is: For example, random vibration analysis is performed on the vehicle body cladding structure. For each constraint location in the finite element model of the vehicle body cladding structure, a white noise acceleration power spectrum with an amplitude of 1g and a bandwidth of 1~120Hz is applied in the X, Y, and Z directions. When inverting the frequency response function matrix, since the number of preset stress points is greater than the number of loads to be identified, the frequency response function matrix is ​​not a square matrix. It can be solved by calculating the generalized inverse of the frequency response function matrix. Therefore, the frequency response function matrix of each preset stress point is calculated. : Then, using the truncated singular value decomposition (TSVD) regularization principle, the excitation spectrum PSD is obtained based on the frequency response function matrix and the target response spectrum. In this step, during the inversion of the frequency response function matrix, matrix ill-conditioning can occur, leading to instability in the numerical solution. This is especially problematic near the structure's resonant frequency, often resulting in distorted load identification. In vibration response-based load identification, the truncated singular value decomposition (SVD) method demonstrates good identification performance. Removing smaller singular values ​​can control the stability of the solution process, thereby reducing errors caused by matrix ill-conditioning. When using the truncated SVD method, the frequency response matrix A is first inverted using singular value decomposition. Assuming… and It is a unitary matrix. Let A be a diagonal matrix containing the singular values ​​of A. The inverse of matrix A is:

[0065] Assumption For one A diagonal matrix containing the first l singular values ​​of A. for eigenvalues, for positive singular values, for:

[0066] Assumption For one The singular value decomposition result of the zero matrix is:

[0067] Singular Value Matrix The inverse is represented as:

[0068] Substituting the target response spectrum and frequency response function matrix into the triaxial random vibration load identification formula, and combining the corresponding X, Y, and Z axis acceleration excitation PSDs obtained by the TSVD regularization method, the solution process... It is not difficult to satisfy the full rank of the columns. By selecting the truncation parameter k, the singular values ​​of the first k orders are truncated and the smaller singular values ​​are discarded. The calculated matrix A is more stable than the original matrix.

[0069] Step 104: The test spectrum is transmitted to the vibration table so that when the vibration table vibrates according to the test spectrum, fatigue testing is performed on the vehicle body covering structure to be tested.

[0070] The basic principle of vibration table testing is to accurately reproduce a given vibration environment (i.e., "test spectrum") through a controlled electromechanical system, thereby enabling efficient and reliable fatigue strength and performance evaluation of the specimen (vehicle body covering structure) in the laboratory.

[0071] After obtaining the test spectrum, the vibration table can reproduce the real load environment during train operation, thus enabling more accurate fatigue testing.

[0072] Furthermore, if the test spectrum is a time-compressed PSD, then applying this test spectrum to a vibration table in the laboratory can accurately reproduce the major fatigue damage experienced by the train over decades of operation within days or weeks.

[0073] In a feasible implementation, based on the damage equivalence principle, the excitation spectrum PSD is converted into a time-compressed test spectrum, including: The excitation PSD values ​​corresponding to the preset frequency bands are extracted to generate a simplified excitation spectrum PSD. Based on the damage equivalence principle, the simplified excitation spectrum PSD is converted into a time-compressed test spectrum.

[0074] Excitation PSDs are characterized by high frequency resolution and complex spectral shapes. While high-resolution PSDs can accurately describe load details, directly using them to drive shaking tables presents challenges: First, overly complex spectral shapes impose a heavy computational burden on the shaking table control system, affecting its stability and real-time response accuracy; second, fatigue damage is essentially a broadband energy accumulation process, dependent on the overall vibration magnitude in key frequency bands, rather than isolated frequency details. Therefore, when converting the excitation PSD into a time-compressed test spectrum, the excitation spectrum PSD can be simplified first.

[0075] For example, the stimulus PSD can be simplified in the following ways: Calculate the power spectral density values ​​in the excitation spectrum PSD corresponding to the 1 / 6 octave frequency, and connect them to form a simplified excitation spectrum PSD.

[0076] Among them, the frequency of 1 / 6 octave band has a high degree of matching with the main peak frequency of the original excitation spectrum, which reduces the complexity of the original excitation spectrum and effectively preserves its main energy components, thereby greatly improving control efficiency and test robustness, and ensuring that accelerated fatigue testing is both reliable and easy to perform.

[0077] Then, based on the damage equivalence principle, the simplified excitation spectrum PSD is converted into a time-compressed test spectrum.

[0078] In a feasible implementation, the test spectrum can be obtained through the following steps: Step 401: For the simplified excitation spectrum PSD, calculate the extreme response spectrum (ERS) and fatigue damage spectrum (FDS) of the vehicle body covering structure under all working conditions throughout its entire life cycle.

[0079] The Limit Response Spectrum (ERS) describes the maximum response of a single-degree-of-freedom system when subjected to random load excitation. By calculating the ERS, the maximum response of the structure at different natural frequencies can be predicted based on the power spectral density (PSD) of the input load using a formula that considers the dynamic amplification factor (Q) and the peak factor (related to the duration of vibration).

[0080] Assumption: For the input signal at frequency The value below; This refers to the dynamic amplification factor, where the dynamic amplification factor is... For structural damping.

[0081] The formula for calculating the limiting response spectrum ERS is:

[0082]

[0083] Where T is the duration of the vibration. It is frequency The system experiences a total number of vibrational cycles within time T. The more cycles, the greater the probability of a peak value occurring. It is a mathematical description of this probability, which follows... It increases slowly as it increases. It is the acceleration limit response spectrum. It is the displacement limit response spectrum.

[0084] The ERS curve obtained through the above steps can intuitively represent the maximum acceleration (inertial force) or maximum relative displacement that a structure may withstand at different natural frequencies under a given random vibration environment. This is an important tool for assessing whether a structure will suffer a one-time overload failure.

[0085] The fatigue damage spectrum (FDS) describes the distribution of structural fatigue damage with natural frequencies. By calculating the FDS, based on Miner's linear cumulative damage rule and the material's S&N curve, the amount of fatigue damage accumulated at different natural frequencies in a virtual single-degree-of-freedom system can be quantitatively predicted.

[0086] The FDS is directly approximated from the simplified excitation PSD based on the Miner damage criterion, assuming K is the stiffness of the SDOF system and parameters b and C are the material SN curves. The parameters, The function is: The formula for calculating the fatigue damage spectrum (FDS) is: For example, the default values ​​for each parameter can be selected. , , , The limiting response spectrum ERS and fatigue damage spectrum FDS per unit time 1s were obtained by calculation.

[0087] The FDS curve obtained through the above steps can intuitively quantify how much fatigue damage a structure accumulates due to cyclic stress at different natural frequencies under a given random vibration environment and duration. This is a key basis for assessing whether a structure will experience fatigue failure during long-term use.

[0088] Step 402: The ERS and FDS are summed to obtain the total target ERS and the total target FDS.

[0089] After obtaining the fatigue damage spectrum under each working condition, the limiting response spectrum ERS and fatigue damage spectrum FDS need to be cumulatively calculated based on the number of cycles experienced by each working condition throughout the entire life cycle to obtain the total limiting response spectrum and the total fatigue damage spectrum. Assuming... The PSD of the spectrum corresponding to the i-th working condition, The number of response loops corresponding to the i-th operating condition. The damage spectrum corresponding to the i-th working condition, For the damage cycle number corresponding to the i-th working condition, the total limiting response spectrum and the total fatigue damage spectrum are as follows:

[0090]

[0091] Step 403: Based on the total target damage amount and the equivalent test time, deduce the target test spectrum.

[0092] The total target damage is obtained from the total fatigue damage spectrum (FDS) and represents the sum of all fatigue damage that the vehicle body cladding structure will experience throughout its entire design life. The equivalent test time represents the total duration of the vibration table test. In other words, the total target damage and the equivalent test time specify the time (equivalent test time) during which the vibration table must achieve the test effect of the "total target damage" on the vehicle body cladding structure.

[0093] The equivalent test time can be set manually or calculated based on the damage equivalence principle.

[0094] The target experimental spectrum can be obtained in the following ways: Assumption The total target damage amount, For safety reasons, For the equivalent test time, the target test spectrum is equivalent to the total damage generated by the simplified excitation PSD. Therefore, the target test spectrum can be expressed as: For example, if the design life of a train is 30 years, the train runs for 300 days a year, and the average running time per day is 12 hours, and assuming that the train has an average of 3 open-track intersections per hour during operation, then the total number of open-track intersections during the entire design life cycle is 324,000. Based on the aforementioned steps, the total target damage amount during the entire service life can be calculated. If the equivalent test time is set to 5 hours, then the target test spectrum equivalent to 5 hours can be obtained according to the above formula.

[0095] Step 404: In response to determining that the ERS of the target test spectrum is greater than the total target ERS and that the frequency domain characteristics are consistent with the PSD of the excitation spectrum, the target test spectrum is determined as the time-compressed test spectrum.

[0096] If the target test spectrum is basically consistent with the simplified excitation PSD (hereinafter referred to as the original spectrum) and the curve of the target test spectrum is higher than that of the original spectrum, it indicates that the target test spectrum basically retains the frequency domain characteristics of the original spectrum, but the energy level at each frequency is higher than that of the original spectrum.

[0097] If the limiting response spectrum (ERS) of the target experimental spectrum is greater than the overall target ERS, it indicates that the acceleration effect of the target experimental spectrum is reasonable.

[0098] In summary, the target test spectrum is determined to be the time-compressed test spectrum. This allows the test spectrum to achieve the effect of accelerating bench vibration fatigue testing while better ensuring consistency in structural failure modes and damage.

[0099] This application provides a testing method, apparatus, equipment, and medium for a train body covering structure. Considering that trains are affected by airflow and vibration (aerodynamic loads and vibration loads) during operation, the durability of the body covering structure is mainly related to the loads (aerodynamic loads and vibration loads). Based on this, by setting sensors at preset stress points on the train body covering structure, the actual acceleration data at these preset stress points detected during train operation can be obtained. Thus, using the mathematical model of the body covering structure, the location of the preset stress points on the body covering structure, and the acceleration data detected by the sensors, the mapping relationship between the body covering structure and the load (under real operating conditions) can be derived. Then, based on the mapping relationship between the body covering structure and the load, the required test spectrum (PSD) can be derived.

[0100] In this way, by applying a test spectrum to the vibration table, the fatigue damage and ultimate response of the vehicle body covering structure during its entire life cycle can be equivalently reproduced in the laboratory.

[0101] In summary, the technical solution provided by the embodiments of this application can comprehensively consider the influence of aerodynamic loads and vibration loads on the cladding structure, and more accurately evaluate the fatigue strength of the cladding structure, providing an effective means for bench testing of non-enclosed structures such as vehicle body cladding that are greatly affected by aerodynamic loads.

[0102] Based on the same technical concept, this application also provides a testing device for train body covering structure, the device comprising: The data acquisition module 501 is used to acquire acceleration data detected by at least one sensor during train operation; the at least one sensor is set at a preset stress point of the vehicle body covering structure.

[0103] The relationship determination module 502 is used to determine the mapping relationship between the vehicle body covering structure and the load based on the mathematical model of the vehicle body covering structure.

[0104] The reverse deduction module 503 is used to deduce the test spectrum based on the acceleration data and the mapping relationship.

[0105] The test module 504 is used to transmit the test spectrum to the vibration table so that when the vibration table vibrates according to the test spectrum, fatigue testing is performed on the vehicle body covering structure to be tested.

[0106] The relationship determination module is used to determine the mapping relationship between the vehicle body covering structure and the load based on the mathematical model of the vehicle body covering structure, for the following purposes: Construct a finite element model of the vehicle body covering structure.

[0107] An excitation with a preset frequency is applied to the finite element model to obtain a frequency response function matrix; the frequency response function matrix is ​​used to characterize the mapping relationship between the vehicle body covering structure and the load.

[0108] In one feasible implementation, the device further includes: The first generation module is used to generate the power spectral density (PSD) during train operation based on the acceleration data.

[0109] The reverse deduction module is used to deduce the test spectrum based on the acceleration data and the mapping relationship, including: Based on the power spectral density (PSD) and the frequency response function matrix, the excitation spectrum (PSD) is calculated by inversion.

[0110] Based on the damage equivalence principle, the excitation spectrum PSD is converted into a time-compressed test spectrum.

[0111] In one feasible implementation, the back-calculation module is used to convert the excitation spectrum PSD into a time-compressed test spectrum based on the damage equivalence principle, including: Extract the excitation PSD value corresponding to the preset frequency band and generate a simplified excitation spectrum PSD.

[0112] Based on the damage equivalence principle, the simplified excitation spectrum PSD is transformed into a time-compressed test spectrum.

[0113] In one feasible implementation, the preset stress point is located at the connection of the train body covering structure, and the connection includes at least one of the following locations: The welds of the skirt support frame, the welds of the skirt base frame mounting seat, the welds of the central covering hanger, and the connection area of ​​the central base plate.

[0114] In one feasible implementation, the relationship determination module is used to apply an excitation containing a preset frequency to the finite element model to obtain a frequency response function matrix, including: Determine the constraint positions in the finite element model that correspond to the preset stress points.

[0115] A unit white noise acceleration spectrum is applied in the X, Y, and Z axes at the constrained position.

[0116] The frequency response function matrix is ​​obtained by regularizing the ill-conditioned matrix through truncated singular value decomposition (TSVD).

[0117] In one feasible implementation, the back-calculation module is used to convert the simplified excitation spectrum PSD into a time-compressed test spectrum based on the damage equivalence principle, including: For the simplified excitation spectrum PSD, the extreme response spectrum (ERS) and fatigue damage spectrum (FDS) of the vehicle body covering structure under all working conditions throughout the entire life cycle are calculated.

[0118] The ERS and FDS are summed to obtain the total target ERS and the total target FDS.

[0119] Based on the total target damage amount and the equivalent test time, the target test spectrum can be deduced.

[0120] In response to determining that the ERS of the target test spectrum is greater than the total target ERS and that the frequency domain characteristics are consistent with the PSD of the excitation spectrum, the target test spectrum is determined as the time-compressed test spectrum.

[0121] Figure 6 The diagram illustrates the structure of an electronic device provided in an embodiment of this application, including a processor 601, a storage medium 602, and a bus 603. The storage medium 602 stores machine-readable instructions executable by the processor 601. When the electronic device runs the test method for the train body covering structure as described in the embodiment, the processor 601 communicates with the storage medium 602 via the bus 603, and the processor 601 executes the machine-readable instructions to perform the steps as described in the embodiment.

[0122] In this embodiment, the storage medium 602 may also execute other machine-readable instructions to perform other test methods as described in the embodiment. For details on the specific execution steps and principles, please refer to the description of the embodiment, which will not be repeated here.

[0123] This application also provides a computer-readable storage medium storing a computer program that is executed by a processor to perform the steps as described in the embodiments.

[0124] In this embodiment, the computer program, when run by the processor, can also execute other machine-readable instructions to perform the test methods described in other embodiments. For details on the specific execution steps and principles, please refer to the description of the embodiments, which will not be repeated here.

[0125] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the coupling or direct coupling or communication connection shown or discussed may be through some communication interface; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0126] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0127] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0128] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0129] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of testing a train car body wrap structure, comprising: The method comprises: obtaining acceleration data detected by at least one sensor during train operation; the at least one sensor is arranged at a preset stress point of a car body cladding structure; determining a mapping relationship between the car body cladding structure and a load based on a mathematical model of the car body cladding structure; based on the acceleration data and the mapping relationship, deducing a test test spectrum; transmitting the test test spectrum to a vibration table, so that when the vibration table vibrates according to the test test spectrum, a fatigue test is performed on the car body cladding structure to be tested.

2. The test method of claim 1, wherein, Based on the mathematical model of the car body cladding structure, the mapping relationship between the car body cladding structure and the load is determined, comprising: constructing a finite element model of the car body cladding structure; applying an excitation containing a preset frequency to the finite element model to obtain a frequency response function matrix; the frequency response function matrix is used to represent the mapping relationship between the car body cladding structure and the load.

3. The test method of claim 2, wherein, The method further comprises: based on the acceleration data, generating a power spectral density (PSD, Power Spectral Density) during train operation; based on the acceleration data and the mapping relationship, deducing a test test spectrum, comprising: based on the power spectral density PSD and the frequency response function matrix, inverse calculation of the excitation spectrum PSD; based on the damage equivalent principle, converting the excitation spectrum PSD into a time-compressed test test spectrum.

4. The test method of claim 3, wherein, Based on the damage equivalent principle, the excitation spectrum PSD is converted into a time-compressed test test spectrum, comprising: extracting the excitation PSD value corresponding to the preset frequency point to generate a simplified excitation spectrum PSD; based on the damage equivalent principle, the simplified excitation spectrum PSD is converted into a time-compressed test test spectrum.

5. The test method of claim 4, wherein, Based on the damage equivalent principle, the simplified excitation spectrum PSD is converted into a time-compressed test test spectrum, comprising: for the simplified excitation spectrum PSD, calculating the limit response spectrum (ERS, Extreme Response Spectrum) and the fatigue damage spectrum (FDS, Fatigue Damage Spectrum) of the car body cladding structure under all working conditions in the whole life cycle; accumulating the ERS and FDS respectively to obtain the total target ERS and the total target FDS; according to the total target damage amount and the equivalent test time, deducing a target test spectrum; in response to determining that the ERS of the target test spectrum is greater than the total target ERS, and the frequency domain characteristics are consistent with the excitation spectrum PSD, the target test spectrum is determined as the time-compressed test test spectrum.

6. The test method of claim 2, wherein, applying an excitation containing a preset frequency to the finite element model to obtain a frequency response function matrix, comprising: determining the constraint position corresponding to the preset stress point in the finite element model; applying unit white noise acceleration spectrum in X, Y and Z directions at the constraint position; through truncated singular value decomposition (TSVD, Truncated Singular Value Decomposition) regularization processing of the ill-conditioned matrix, the frequency response function matrix is obtained.

7. The test method of claim 1, wherein, The preset stress point is arranged at a connection of a train body cladding structure, and the connection includes at least one of the following positions: a skirt support weld, a skirt underframe mounting seat weld, a middle cladding hanger weld, and a middle bottom plate connection area.

8. A testing device for a train car body wrap structure, comprising: The device comprises: a data acquisition module configured to acquire acceleration data detected by at least one sensor during train operation, wherein the at least one sensor is arranged at a preset stress point of a train body cladding structure; a relationship determination module configured to determine a mapping relationship between the train body cladding structure and a load based on a mathematical model of the train body cladding structure; a backstepping module configured to backstep a test test spectrum based on the acceleration data and the mapping relationship; a test module configured to transmit the test test spectrum to a vibration table, so that the vibration table vibrates according to the test test spectrum to perform a fatigue test on a train body cladding structure to be tested.

9. An electronic device, comprising: comprise: a processor, a storage medium, and a bus, wherein the storage medium stores machine readable instructions executable by the processor, the processor and the storage medium communicate through the bus when the electronic device is running, and the processor executes the machine readable instructions to perform the steps of the test method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by the processor to perform the steps of the test method according to any one of claims 1 to 7.

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