TRB sheet index modulation width control parameter identification method

Abstract

The invention discloses a TRB plate index modulation width control parameter identification method, and belongs to the field of new energy automobile design. In order to solve the problems that in existing TRB material parameter identification, a traditional equal-width sample is fractured in a thin area, a uniform-cross-section-area sample is fractured in a thick area, the testing cost is high, the efficiency is low, and hypothesis lacks physical basis, the method is achieved through the six steps that basic parameters of a TRB plate are measured, a uniform-cross-section-area sample width control function is deduced, and the TRB material parameter identification result is obtained; a novel width control function is designed by using an index modulation method, parametric modeling is performed, width control parameters are optimized to enable the transition area to deform sufficiently and uniformly, and an optimal sample is tested based on a DIC technology to obtain a real stress-strain curve. According to the method, the limitation of the prior art is overcome, only the thin area and the thick area need to be tested, the cost is remarkably reduced, the material plasticity information is efficiently obtained, and support is provided for TRB technical engineering application.

Description

Technical Field

[0001] This invention relates to the field of new energy vehicle design technology, and in particular to a method for identifying TRB sheet metal index modulation width control parameters. Background Technology

[0002] With the increasing demands for lightweighting and safety in new energy vehicles, tailor-rolled blank (TRB) technology has become a core research direction in the field of new energy vehicle manufacturing due to its advantages in optimizing material properties and reducing weight. TRB achieves continuous variation in plate thickness through rolling processes, meeting structural design performance requirements while significantly reducing weight. However, due to its non-uniform thickness, traditional uniform-width single-tensile specimens are no longer effective in characterizing the mechanical properties of the material.

[0003] In the prior art, patent CN104677706A discloses a TRB specimen design with a constant cross-sectional area, but it often fractures in the thicker region during tensile testing, making it difficult to obtain sufficient material plasticity information. Patent CN107478475A proposes a TRB specimen design method, which requires testing the yield strength of a constant-thickness plate corresponding to the intermediate thickness, resulting in high testing costs and long testing times. In published literature, Zhang Ziqiang et al. assumed the material to be ideally rigid-plastic, introduced a width correction coefficient, and combined finite element analysis and genetic algorithms to optimize the specimen width, designing a variable-width specimen that ensures uniform deformation in the transition zone. However, this method fails to achieve accurate or even failed width optimization results when the material property gradient is large, due to the lack of clear physical basis for the ideal rigid-plastic assumption and the width correction coefficient. How to efficiently design variable-width TRB specimens and achieve model parameterization for material parameter identification has become crucial for the widespread application of TRB technology.

[0004] Based on the above analysis, the problems and defects of the existing technology are as follows: the non-uniformity of TRB sheet material makes traditional equal-width specimens no longer applicable; the existing variable-width specimen design method has high testing costs and long testing time; the ideal rigid-plastic assumption and width correction coefficient lack physical meaning, resulting in large width optimization errors, low design efficiency, and even design failure, thus limiting the engineering application of TRB technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for identifying TRB sheet index modulation width control parameters. This method overcomes the limitations of existing technologies, requires only testing thin and thick areas, significantly reduces costs, efficiently obtains material plasticity information, and provides support for the engineering application of TRB technology.

[0006] To achieve the above objectives, the present invention provides a method for identifying TRB sheet material index modulation width control parameters, the steps of which are as follows:

[0007] S101: Obtain the thickness distribution parameters of TRB sheet material using non-contact measuring equipment, including the thickness t of the thickest area. H The thickness of the thin region t0 and the length of the transition region L;

[0008] S102: The reference width function is constructed based on the principle of equal cross-sectional area, and is expressed as:

[0009]

[0010] Where w0 is the width of the thin region, t0 is the thickness of the thin region, and t i For any position in the transition region, w i The width of the transition zone at any position;

[0011] S103: Introducing a continuously adjustable width control parameter n∈[0,1], a novel TRB width control function is designed using the exponential modulation method, expressed as:

[0012]

[0013] Where, η i For the rolling rate, there is a one-to-one correspondence between the rolling rate and the thickness distribution, when t i When the thickness of the thin region is t0, η reaches its maximum value, denoted as η0;

[0014] S104: A novel parametric model of the TRB tensile specimen is established in a right-handed coordinate system, where the rolling ratio η is mapped to the spatial coordinates, expressed as:

[0015]

[0016] Where y = y at any point i At any point x = x i Rolling ratio η = η i

[0017] S105: To ensure sufficient tensile strain at all thickness locations in the transition zone, the TRB tensile specimen width is designed, the modulation parameter n is optimized, and a bi-objective optimization function incorporating strain mean and variance is established as follows:

[0018] min{λ·[(-Avg(ε1)]+(1-λ)·Var(ε1)}stσ2≤σ1 / M

[0019] Wherein, the modulation parameter n is the design variable, 0≤n≤1; λ is the weighting coefficient, λ∈[0,1]; Avg(ε1) is the average value of the axial strain at the nodes of the TRB tensile transition zone; Var(ε1) is the variance of the axial strain at the nodes of the transition zone; σ1 and σ2 are the axial stress and transverse stress of the tensile specimen, respectively, M>10;

[0020] S106: Based on the optimal modulation parameter n obtained in S105, establish the optimal TRB tensile specimen model according to the method in S104, then process the corresponding tensile specimen using wire EDM technology, and obtain the true stress-strain curve of the tensile specimen based on digital image correlation technology, as shown below:

[0021]

[0022] ε t =ln(1+ε e )

[0023] Take any one of the N portions of the optimal TRB tensile specimen transition region, denoted as r, with thickness and width t respectively. r and w r , σ t Let F be the actual stress, F be the load-time history, and ε be the load-time history. e Let ε be the strain-time history corresponding to the r-th part. t To respond to real situations.

[0024] Preferably, in S103, when n=0, the novel TRB width control function degenerates into a specimen with equal cross-sectional area; when n=1, the novel TRB width control function degenerates into a traditional standard tensile specimen.

[0025] Preferably, in S104, the reference coordinate system of the parameterized model of the novel TRB tensile specimen is established as follows: the origin of the coordinate system is taken as the junction of the thick section of the TRB transition zone and the parallel section, the y-axis is the tensile direction of the specimen, the x-axis points to the material, and the z-axis is perpendicular to the sheet metal.

[0026] Preferably, in S105, a piecewise search algorithm is used to optimize the value of n, specifically including:

[0027] Divide the interval [0,1] into P equal parts, and calculate the objective function value for each division point n = 0, n = 1 / P, n = 2 / P…n = 1; sort the objective function values, find the n corresponding to the smallest objective function value, and denot it as n = Q / P; for the interval… Divide into P parts, repeat the above calculation process, until the interval width is 2. P The value is less than 0.0001; at this point, the average value of the left and right endpoints of the interval is taken as the optimal modulation parameter n.

[0028] Preferably, in S106, the transition region is discretized into N≥10 sub-regions, and the actual stress-strain curve of each region is calculated independently.

[0029] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0030] This invention proposes a method for identifying the width control parameter of TRB (Transformer of Biologically Modulated) sheet metal. A novel TRB width control function is designed using the exponential modulation method. When the modulation parameter takes values ​​within the range of 0 to 1, it can cover all cases, including traditional tensile specimens, specimens with constant cross-sectional area, and specimens with variable width, overcoming the limitations of existing methods that rely on the ideal rigidity-plasticity assumption of the material and lack physical basis for the width correction coefficient. Furthermore, the parameterized model of the TRB specimen constructed using the exponential modulation method, combined with DIC (Distributed Injection) technology, only requires two sheet thickness tests (thin and thick sections) to achieve the optimal width design of the TRB specimen, significantly reducing the testing cost of existing methods. More importantly, the method of this invention is simple and efficient, requiring no complex testing experiments or optimization algorithms, providing strong technical support for the engineering application of TRB technology.

[0031] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a flowchart of an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram illustrating the measurement of basic parameters of TRB sheet material according to an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the basic specimen shape of the novel TRB tensile specimen according to an embodiment of the present invention.

[0036] Figure 4 This is a schematic diagram of the basic specimen for the novel TRB tensile specimen according to an embodiment of the present invention.

[0037] Figure 5 This is a schematic diagram showing the tensile test results of a conventional standard tensile specimen and a specimen with an equal cross-sectional area according to an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram of the basic specimen parameterization for the novel TRB tensile specimen of this invention.

[0039] Figure 7 This is a schematic diagram of the finite element modeling of the novel TRB tensile specimen according to an embodiment of the present invention. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] Example

[0043] like Figure 1 As shown, the present invention provides a method for identifying TRB sheet material index modulation width control parameters, comprising the following steps:

[0044] S101: Obtain the thickness distribution parameters of TRB sheet material using non-contact measuring equipment, including the thickness t of the thickest area. H The thickness of the thin region t0 and the length of the transition region L.

[0045] In this embodiment, the thickness of the thin area of ​​the TRB sheet is t0 = 1.3, and the thickness of the thick area is t H =1.7, transition zone length L=40, unless otherwise specified, the length unit below is millimeters.

[0046] S102: Construct the reference width function based on the principle of equal cross-sectional area. The specific steps are as follows:

[0047] (1) As Figure 3 As shown, referring to GB / T228.1-2010 "Metallic materials, tensile testing—Part 1: Tests at room temperature," the width of the clamping end is designed to be 30 mm, the initial width of the parallel section w0 = 12.5 mm, the length of the parallel section is 75 mm, the total length of the specimen is 180 mm, and the radius of the transition arc from the clamping end to the parallel section is 25 mm. The dashed line in the figure represents the basic specimen shape of the new TRB tensile specimen. The above basic specimen dimensions can be selected according to actual needs and in accordance with the national standard GB / T228.1-2010.

[0048] (2) Figure 4 As shown, the TRB sheet transition zone is placed in the middle of the above-mentioned basic sample, the width of the thin section is taken as w0, and the width of the thick section is recorded as w. H The thickness of the transition zone at any location is t. i The width of the transition zone at any position is w i .

[0049] (3) The rolling rate is defined as the ratio of the thickness change of the sheet metal after rolling, i.e.

[0050]

[0051] In the formula, η i The rolling rate is the rolling percentage, and there is a one-to-one correspondence between the rolling percentage and the thickness distribution.

[0052] By definition, when t i Take the thickness t of the thick area H When t, η = 0; when t i When the thickness of the thin region is t0, η reaches its maximum value, denoted as η0, and the calculation formula is as follows:

[0053]

[0054] Therefore, the rolling ratio η ranges from 0 to η to 0.2353.

[0055] (4) Based on the concept of equal cross-sectional area, the product of the thickness and width of the TRB specimen is equal at any position, that is:

[0056] w0·t0=w i ·t i =w H ·t H =12.5 × 1.3 = 16.25 (3)

[0057] Once the TRB sheet material is selected, its thickness distribution is determined; therefore, thickness is a known quantity in the design. From the above formula, it can be seen that the design problem for TRB specimens is to design specimens with arbitrary thickness t. i The corresponding width w i This allows for significant plastic strain at various thickness locations during the tensile testing of the specimen, thereby obtaining sufficient information about the material's plasticity.

[0058] From equation (3), we can see that:

[0059]

[0060] Eliminate the thickness parameter t of the thick region from equations (1) and (2). H Substituting this into the above equation, we can obtain:

[0061]

[0062] From the above formula, it can be seen that when the rolling ratio reaches its maximum value η0, the width reaches its maximum value, w0; when the rolling ratio reaches its minimum value 0, the width w i Just take the thickness and width w H The calculation formula is as follows:

[0063] w H =(1-η0)·w0=9.5586 (6)

[0064] Once the thickness distribution of the sheet is determined, its rolling rate distribution is also determined accordingly. Then, the width at any thickness position can be calculated according to the equal cross-sectional area width calculation formula (5).

[0065] S103: Introduce a continuously adjustable width control parameter n∈[0,1], and design a novel TRB width control function using the exponential modulation method. The specific steps are as follows:

[0066] (1) As Figure 5 As shown, tensile tests were conducted on traditional equal-width standard tensile specimens and equal-section area specimens designed in step two above for TRB sheet. The results showed that when using standard specimens, tensile deformation was concentrated in the thinner region of the specimen. This is because the specimen width is uniform, and the thinner region has a smaller cross-sectional area and experiences greater tensile stress, thus leading to more concentrated deformation. When using equal-section area tensile specimens, the results showed that tensile deformation was often concentrated in the thicker region of the specimen. This is because the equal-section area specimen experiences the same tensile stress at all thickness locations, while the material strength in the thicker region is weaker than in the thinner region. Therefore, deformation is mainly concentrated in the weaker, thicker region. These experimental results are consistent with literature reports.

[0067] The above experimental analysis shows that the deformation of both specimens was not uniform during the tensile process. One specimen broke in the thin area and the other broke in the thick area. This means that optimizing the width distribution of the specimen can make the specimen break in the transition area, so as to obtain more information about the plasticity of the material.

[0068] (2) A novel TRB width control function is designed using the exponential modulation method as follows:

[0069]

[0070] In the formula, n is the width modulation parameter.

[0071] As can be seen from equation (7), when the width modulation parameter n is 0, the above equation degenerates into the equal cross-sectional area specimen in step two; when n is 1, the above equation degenerates into the traditional standard tensile specimen; when n takes any value between 0 and 1, a new type of TRB tensile specimen between the traditional tensile specimen and the equal cross-sectional area specimen in the width distribution position can be designed.

[0072] It is worth noting that when η i When the value is 0, the above formula can be used to calculate the thickness and width w. H The formula is as follows:

[0073] w H =(1-η0) 1-n ·w0=0.7647 (1-n)×12.5 (8)S104: A novel parametric model of the TRB tensile specimen profile is established in the right-hand coordinate system, and the rolling ratio η forms a mapping relationship with the spatial coordinates. The specific steps are as follows:

[0074] (1) As Figure 6 As shown, a right-handed coordinate system is established with the intersection of the thick section of the TRB transition zone and the parallel section as the origin, the y-axis as the tensile direction of the specimen, the x-axis pointing towards the material, and the z-axis perpendicular to the sheet metal. Using this coordinate system as a reference, the new TRB tensile specimen parameterization model designed in step three is constructed.

[0075] (2) From geometric relationships, we know the following information about the y-coordinate direction: at the origin, y = 0, and the rolling ratio η = 0; at any point, y = y i Rolling ratio η = η i At the junction of the thin zone and the parallel section, y = -L, and the rolling ratio η = η0. Therefore, according to the linear proportional relationship:

[0076]

[0077] Furthermore, it can be deduced that the y-coordinate y of arbitrary thickness can be obtained. i as follows:

[0078]

[0079] (3) From the geometric relationship, the formula for calculating the x-direction coordinate is as follows:

[0080]

[0081] Substituting formulas (7) and (8) into the above equation and rearranging, we can obtain the x-coordinate x for any thickness. i as follows:

[0082]

[0083] The parameterized equations of equations (9) and (11) can be used to create a graphic representation of a novel TRB tensile specimen in any modeling software (e.g., SolidWorks, CATIA, etc.).

[0084] S105: To ensure sufficient tensile strain at all thickness locations in the transition zone, the TRB tensile specimen width is designed, the modulation parameter n is optimized, and a bi-objective optimization function incorporating strain mean and variance is established. The specific steps are as follows:

[0085] (1) To provide material data support for the new TRB tensile specimens, standard single tensile tests were performed on the equal-thickness plates corresponding to the thick and thin regions of TRB, in accordance with GB / T228.1-2010 "Metallic materials - Tensile testing - Part 1: Test method at room temperature", to obtain the true stress-strain curves of the thick and thin regions.

[0086] (2) Based on the linear assumption of yield stress, the true stress-strain curve of any intermediate thickness can be interpolated from the stress-strain curves of the thin and thick regions. The calculation formula is as follows:

[0087]

[0088] It is worth noting that the material information obtained by interpolation is only used for tensile finite element simulation in the specimen design process. The final stress-strain data in the transition zone is directly measured from a single tensile specimen. Therefore, the interpolation error will only affect the effect of the specimen design, but will not affect the authenticity of the final test results.

[0089] (3) Figure 7 As shown, a new TRB tensile specimen model is established in SolidWorks based on the parameterized equations of step four and the basic specimen shape parameters of the TRB tensile specimen in step two. The model is then imported into LS-DYNA to establish a finite element model. In order to accurately simulate the differences in plastic material properties at different plate thicknesses, the transition zone is divided into N discrete regions and corresponding real stress-strain curves are set. The curve of each discrete region is obtained by interpolation according to the average plate thickness of the corresponding region by formula (31).

[0090] (4) The core objective of TRB tensile specimen width design is to optimize the modulation parameter n so that sufficient tensile strain occurs at all thickness locations in the transition zone. Therefore, the following bi-objective optimization function is established:

[0091] min{λ·[(-Avg(ε1)]+(1-λ)·Var(ε1)}stσ2≤σ1 / M (14)

[0092] In the formula, the modulation parameter n is the design variable; λ is the weighting coefficient, with a value range of 0 to 1; Avg(ε1) is the average value of the axial strain at the nodes of the TRB tensile transition zone. The larger the value, the more fully the specimen is deformed; Var(ε1) is the variance of the axial strain at the nodes of the transition zone. The smaller the value, the more uniform the specimen deformation; σ1 and σ2 are the axial stress and transverse stress of the tensile specimen, respectively. M should be greater than 10, indicating that the transverse stress is much smaller than the axial stress, so as to ensure that the new TRB specimen is in a uniaxial tensile state during the tensile process.

[0093] (5) Divide the design variable n into P parts, and calculate the objective function values ​​for n=0, n=1 / P, n=2 / P…n=1 respectively according to the above method and mathematical model (14). Sort the objective function values ​​and find the n corresponding to the smallest objective function value, denoted as n=Q / P; for the interval Divide the interval into P parts and repeat the above calculation process until the interval width 2 / P is less than 0.0001; at this point, take the average value of the left and right endpoints of the interval as the optimal modulation parameter n.

[0094] S106: Based on the optimal modulation parameter n obtained in S105, establish the optimal TRB tensile specimen model according to the method in S104, then process the corresponding tensile specimen using wire EDM technology, and obtain the true stress-strain curve of the tensile specimen based on digital image correlation technology. The specific steps are as follows:

[0095] (1) Based on the optimal modulation parameter n obtained in S105, the optimal TRB tensile specimen model is established according to the method in S104, and then the corresponding tensile specimen is processed by wire cutting technology.

[0096] (2) Tensile tests are conducted on the optimal TRB tensile specimen based on digital image correlation (DIC) technology to obtain tensile load-time and strain-time data at any position. In order to obtain the true stress-strain curve of the specimen, the original data needs to be processed in conjunction with the specimen size.

[0097] (3) Randomly select one of the N parts of the optimal TRB tensile specimen transition zone and record it as r. From S104, we can know that its thickness and width are t respectively. r and w r ,but:

[0098] A0 = w r ·t r (15)

[0099] In the formula, A0 is the initial area of ​​the r-th part.

[0100] σ e =F / A0 (16)

[0101] In the formula, σ e Let F be the engineering stress and F be the load-time history. The actual stress σ is... t It is a correction factor for engineering stress multiplied by strain, taking into account the deformation of the material during the tensile process:

[0102] σ t =σ e ·(1+ε e (17)

[0103] In the formula, ε e Let r be the strain-time history corresponding to the r-th part.

[0104] Real strain ε t It is obtained through engineering strain transformation and can be expressed using logarithmic relations:

[0105] ε t =ln(1+ε e (18)

[0106] By combining the actual strain and actual stress data with the time axis as the reference, the actual stress-strain curve of the material can be obtained.

[0107] The remaining technical features in the above embodiments can be flexibly selected by those skilled in the art to meet different specific practical needs according to actual circumstances. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims. In the above description, numerous specific details have been set forth to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to implement the present invention. In other instances, to avoid obscuring the present invention, well-known techniques, such as specific construction details, operating conditions, and other technical conditions, have not been specifically described.

[0108] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for identifying a TRB sheet index modulation width control parameter, characterized in that, The steps are as follows: S101: Obtain the thickness distribution parameters of the TRB plate material using a non-contact measurement device, including the thick zone thickness t H , the thin zone thickness t0, and the transition zone length L; S102: Construct a reference width function based on the principle of equal cross-sectional area, denoted as: where w0 is the thin zone width, t0 is the thin zone thickness, t i is the transition zone thickness at any location, w i is the transition zone width at any location; S103: Introduce a continuously adjustable width control parameter n, and design a new TRB width control function using exponential modulation method, denoted as: wherein η i is the rolling ratio, which is uniquely determined by the thickness distribution, and t i The maximum value of η is η0, which is taken when the thickness t0 is taken at the thin region. S104: Build a new TRB tensile specimen parameterization model of sample profile in the right-hand coordinate system, and form a mapping relationship between the rolling rate η and the spatial coordinates, denoted as: where y = y i , x = x i , and η = η i S105: In order to make all thickness positions in the transition zone have sufficient tensile strain, the width of the TRB tensile specimen is designed, the modulation parameter n is optimized, and a double-objective optimization function containing the average strain and the variance is established as follows: min{λ·[-Avg(ε1)]+(1-λ)·Var(ε1)}s.t.σ2≤σ1 / M Wherein, the modulation parameter n is the design variable, 0≤n≤1; λ is the weight coefficient, λ∈[0, 1]; Avg(ε1) is the average value of the axial strain of the TRB tensile transition zone node; Var(ε1) is the variance of the axial strain of the transition zone node; σ1 and σ2 are the axial stress and transverse stress of the tensile specimen respectively, M>10; S106: According to the optimal modulation parameter n obtained in S105, the optimal TRB tensile specimen model is established according to the method of S104, and then the corresponding tensile specimen is processed by using wire cutting technology, and the real stress-strain curve of the tensile specimen is obtained based on digital image correlation technology, denoted as: ε t = ln(1 + ε e ) Take one of the N portions of the transition zone of the optimal TRB tensile specimen, record it as r, whose thickness and width are t and w, respectively r and w r , σ t is the true stress, F is the load-time history, ε e is the strain-time history corresponding to the rth portion, and ε t is the true strain.

2. The method of claim 1, wherein the TRB sheet index modulation width control parameter is identified by: In S103, when n=0, the new TRB width control function degenerates into an equal cross-sectional area specimen; when n=1, the new TRB width control function degenerates into a traditional standard tensile specimen.

3. The method of claim 2, wherein the TRB sheet index modulation width control parameter is identified by: S103 specifically includes: In S104, the reference coordinate system of the new TRB tensile specimen parameterization model is established as follows: taking the intersection of the thick zone and the parallel section of the TRB transition zone as the coordinate origin, the y-axis direction as the tensile direction of the specimen, the x-axis pointing to the material, and the z-axis perpendicular to the sheet, a right-hand coordinate system is established.

4. The method of claim 3, wherein the TRB sheet index modulation width control parameter is identified by, S102 specifically includes: In S105, the n value is optimized by using a piecewise search algorithm, which specifically includes: The interval [0, 1] is equally divided into P parts, and the objective function values of the division points n = 0, n = 1 / P, n = 2 / P, …, n = 1 are calculated respectively; the objective function values are sorted, and the n corresponding to the minimum objective function value is found, which is recorded as n = Q / P; the interval is divided into P parts, and the above calculation process is repeated until the interval width 2 / P is less than 0.0001; at this time, the average value of the left and right endpoints of the interval is taken as the optimal modulation parameter n.

5. The method of claim 4, wherein the TRB sheet index modulation width control parameter is identified by, S102 specifically includes: In S106, the transition zone is discretized into N≥10 sub-regions, and the real stress-strain curve is calculated independently for each region.

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