Strength detection method for simulating stamping, welding and aging processes

Abstract

The invention discloses a strength detection method for simulating stamping, welding and aging processes. The strength detection method comprises the following steps: 1) establishing five initial finite element models; 2) performing stamping simulation by stamping simulation software, and exporting stamping stress and node thickness data; 3) mapping the data into the initial finite element model, performing aging treatment on the model to obtain a stamping-aging finite element model, and exporting stress data of the model; 4) newly creating a stamping-stress text, and writing the exported stress data in sequence; (5) welding simulation software carries out welding simulation, and welding stress data are exported; 6) mapping the data into the initial finite element model, performing aging treatment on the model to obtain a welding-aging finite element model, and exporting stress data of the model; 7) newly creating a welding-stress text, and writing the exported stress data in sequence; and 8) combining to form a strength-stress text, reading strength-stress text data, and carrying out strength analysis on the part.

Description

Technical Field

[0001] The invention relates to the field of simulation, and in particular to a strength detection method for simulating stamping, welding and aging processes. Background Art

[0002] Automobile chassis components, such as subframes, control arms, torsion beams, tie rods, etc., are usually formed into individual parts by stamping steel plates, and then the individual parts are welded to form assemblies. In order to ensure the strength of these parts, simulation experiments are carried out by computer before formal production to predict and evaluate the risk of failure and fatigue fracture of parts under specific working conditions, which has guiding significance for the strength and life design of products. Relevant studies have shown that the stress fluctuation of parts under specific working conditions has a significant impact on the prediction of strength and life. Therefore, the actual stress level of the product under specific working conditions is crucial to the accuracy of strength simulation analysis.

[0003] When performing strength simulation analysis on automobile chassis components, the existing technology usually does not consider the impact of stamping, welding and aging processes on the simulation results. In the actual production process, the steel plate first undergoes a large plastic deformation through a stamping process, is formed into a single part, and then undergoes a natural aging treatment; then the parts are forcibly assembled into components through a welding process, and then undergo a natural aging treatment. These processes will introduce certain residual stresses into the parts. The existing strength analysis method usually converts the three-dimensional digital model of the part into a finite element model, and then directly imports the finite element model of the part into the strength analysis software to solve the stress distribution of the part under specific working conditions, and examines whether the local stress level of the part meets the design requirements. The impact of the residual stress introduced by the stamping, welding and aging processes on the simulation results is not considered.

[0004] Stamping residual stress data can be obtained by exporting stamping simulation software, and welding residual stress data can be obtained by exporting welding simulation software, but the data formats exported by existing stamping simulation software and welding simulation software cannot be read and recognized by strength analysis software. For example, the stress data that can be recognized by the strength analysis software Abaqus is in a text format with the suffix .inp, while the stress data exported by the stamping simulation software DynaForm is in a text format with the suffix .dyn, and the stress data exported by the welding simulation software simufactwelding is in a text format with the suffix .unv. Therefore, the stress data exported by the stamping simulation software DynaForm and the stress data exported by the welding simulation software simufactwelding cannot be recognized by the strength analysis software Abaqus. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention provides a strength detection method for simulating stamping, welding and aging processes. The method adds the stress introduced into the parts by the stamping, welding and aging processes into the strength analysis software, so that the stress distribution of the parts in the simulation is close to the stress distribution of the parts in actual work, thereby ensuring the reliability and accuracy of the part strength simulation analysis.

[0006] The technical solution of the present invention is: a strength detection method for simulating stamping, welding and aging processes, comprising the following steps:

[0007] 1) Establish 5 initial finite element models, two of which are used to simulate stamping and aging, two of which are used to simulate welding and aging, and the last one is used for strength analysis;

[0008] 2) Perform stamping simulation on an initial finite element model through stamping simulation software to form a stamping simulation finite element model, and derive stamping stress and node thickness data based on the stamping simulation finite element model;

[0009] 3) Mapping the exported stamping stress and node thickness data to another initial finite element model through pre-processing software, and performing aging treatment on the model through strength analysis software to obtain a stamping-aging finite element model, and exporting the stress data of the stamping-aging finite element model;

[0010] 4) Create a new stamping-stress text in a format that can be recognized by the strength analysis software. Write keywords at the beginning of the text and write the stress data exported from the stamping-aging finite element model in sequence;

[0011] 5) Perform welding simulation on an initial finite element model through welding simulation software to form a welding simulation finite element model, and derive welding stress data based on the welding simulation finite element model;

[0012] 6) Mapping the exported welding stress data to another initial finite element model through pre-processing software, and performing aging treatment on the model through strength analysis software to obtain a welding-aging finite element model, and exporting the stress data of the welding-aging finite element model;

[0013] 7) Create a new welding-stress text in a format that can be recognized by the strength analysis software. Write keywords at the beginning of the text and write the stress data exported from the welding-aging finite element model in sequence;

[0014] 8) The corresponding data of the stamping-stress text and the welding-stress text are combined to form a strength-stress text. The strength-stress text data is read through the strength analysis software, and the strength analysis of the parts is performed.

[0015] Preferably, the stress data derived from the stamping-aging finite element model are written into the stamping-stress text in the order of unit id number, serial number in the thickness direction, stress tensor S11, stress tensor S22, and stress tensor S12; the stress data derived from the welding-aging finite element model are written into the stamping-stress text in the order of unit id number, serial number in the thickness direction, stress tensor S11, stress tensor S22, and stress tensor S12.

[0016] Preferably, in step 8), the corresponding data merging of the stamping-stress text and the welding-stress text refers to numerically summing the stress tensors S11, stress tensor S22, and stress tensor S12 with the same unit id number and the same serial number in the thickness direction in the stamping-stress text and the welding-stress text.

[0017] Preferably, the aging treatment comprises the following steps:

[0018] a. Model stress self-balance: No load is applied to the model, so that the model can achieve stress self-balance under stress conditions;

[0019] b. Set natural aging and set the field output to stress and displacement.

[0020] Preferably, the aging time for setting natural aging is 5 days.

[0021] The advantages of the present invention are:

[0022] 1. The present invention simulates the stamping, welding and aging processes of parts through stamping simulation software, welding simulation software and strength analysis software to obtain corresponding stress data. By importing these stress data, it is ensured that the stress of the parts in the simulation analysis is close to the stress of the actual working conditions of the parts, making the results of the simulation analysis more reliable and accurate.

[0023] 2. The present invention establishes a text format recognizable by the strength analysis software, and rewrites the exported stamping-aging stress data and welding-aging stress data into a text format recognizable by the strength analysis software, so that the strength analysis software can read and identify the stress introduced into the parts by simulated stamping, welding and aging, thereby ensuring that the results of the simulation analysis are more reliable and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a flow chart of the present invention;

[0025] Figure 2 is the initial finite element model of the front lower control arm of the vehicle in this embodiment;

[0026] Figure 3 It is a stamping simulation finite element model of the front lower control arm of the automobile in this embodiment;

[0027] Figure 4 The data diagram of stamping stress and node thickness of the front lower control arm of the automobile in this embodiment;

[0028] Figure 5 The stamping-aging finite element model of the front lower control arm of the automobile in this embodiment;

[0029] Figure 6 It is the stamping-stress text of the front lower control arm of the automobile in this embodiment;

[0030] Figure 7 The welding-aging finite element model of the front lower control arm of the automobile in this embodiment;

[0031] Figure 8 The welding-stress text of the front lower control arm of the automobile in this embodiment;

[0032] Fig. 9 It is the combined strength-stress of the front lower control arm of the automobile in this embodiment. DETAILED DESCRIPTION

[0033] See also Figures 1 to 9 , a strength detection method for simulating stamping and welding and aging processes, comprising the following steps:

[0034] 1) Establish 5 initial finite element models, see Figure 2 ,In this embodiment, a finite element model of a front lower control arm of an automobile is used for illustration, two of which are used for simulating stamping and aging, two of which are used for simulating welding and aging, and the last one is used for strength analysis;

[0035] 2) Use stamping simulation software DynaForm to perform stamping simulation on an initial finite element model to form a stamping simulation finite element model. Export stamping stress and node thickness data according to the stamping simulation finite element model. Set the output text format of stamping stress and node thickness data to dyna format and name it Lca.dyn. Ensure that the *ELEMENT_SHELL_THICKNESS data segment in the exported data contains the node thickness data of the unit and is consistent with the stamping simulation software DynaForm. At the same time, ensure that the *INITIAL_STRESS_SHELL data segment contains stress tensor data, and the unit of stress is MPa;

[0036] 3) Since the stamping stress and node thickness data are saved in dyna format, which is a common format that most pre-processing software can recognize, the exported stamping stress and node thickness data are mapped to another initial finite element model through the pre-processing software, and the mapping file is selected as Lca.dyn, the mapping type is checked for node thickness and initial stress, the node thickness mapping method is selected as shape function, and the initial stress mapping method is selected as common area. After the mapping is completed, the model is aged by the strength analysis software Abaqus, and the three installation points of the model are constrained to have 1 to 3 degrees of freedom. The aging treatment includes the following steps: a. Model stress self-balance; no load is applied to the model, so that the model is self-balanced under stress conditions; b. Set natural aging, the aging time is 5 days, and the field output is set to stress and displacement. The stamping-aging finite element model is obtained, and the unit id number, stress tensor S11, stress tensor S22, and stress tensor S12 data of the stamping-aging finite element model are exported to form a text and named punch_out.rpt.

[0037] 4) Create a new punching-stress text named punch_time.inp. The format of the text is recognizable by the strength analysis software. Write the keywords *INITIAL CONDITIONS, TYPE=STRESS, SECTION POINTS at the beginning of the text. Write the data exported from the punching-aging finite element model into the text of punch_time.inp in the order of stress data, unit ID number, sequence number in the thickness direction, stress tensor S11, stress tensor S22, and stress tensor S12 separated by English commas; the sequence number in the thickness direction is Arabic numerals 1-5. Figure 6 Take the stress of unit ID 227 as an example, where the values ​​of stress tensor S11, stress tensor S22, and stress tensor S12 are -4.57052, -7.41900, and -3.41470, respectively. The stress tensor after writing into the punch_time.inp text is expressed as

[0038] 227,1,-4.57052,-7.41900,-3.41470

[0039] 227,2,-4.57052,-7.41900,-3.41470

[0040] 227,3,-4.57052,-7.41900,-3.41470

[0041] 227,4,-4.57052,-7.41900,-3.41470

[0042] 227,5,-4.57052,-7.41900,-3.41470

[0043] Write all the unit information in punch_out.rpt into punch_time.inp in the above way to complete the creation of punch-stress text.

[0044] 5) Use the welding simulation software Simufact Welding to simulate the welding of an initial finite element model to form a welding simulation finite element model. Export the welding stress data based on the welding simulation finite element model. The stress data output format is set to the i-deas format and named lca.unv. The unit of stress is MPa. The stress tensor format in lca.unv is converted into a file format that can be recognized by the pre-processing software and renamed to lca.inp for later stress mapping.

[0045] 6) Use the pre-processing software to map the exported welding stress data to another initial finite element model, and select the mapping file as lca.inp. Select the initial stress as the mapping type, and select RBF as the initial stress mapping method. After the mapping is completed, export the text file of the model through the pre-processing software, select Abaqus as the solver, and name it Lca_Map_weld.inp. Open the text file to query the *INITIAL CONDITIONS, TYPE=STRESS, SECTIONPOINTS keyword information. The model is subjected to aging treatment by strength analysis software, and 1 to 3 degrees of freedom of the three installation points of the model are constrained. The aging treatment includes the following steps: a. self-balancing of model stress; no load is applied to the model, so that the model performs self-balancing of stress under stress conditions; b. natural aging is set, the aging time is 5 days, and the field output is set to stress and displacement to obtain a welding-aging finite element model, and the unit id number, stress tensor S11, stress tensor S22, and stress tensor S12 data of the welding-aging finite element model are exported to form a text and named weld_out.rpt.

[0046] 7) Create a welding-stress text named weld_time.inp. The format of the text is recognizable by the strength analysis software. Write the keywords *INITIAL CONDITIONS, TYPE=STRESS, SECTION POINTS at the beginning of the text. Write the data exported from the welding-aging finite element model into the weld_time.inp text in the order of stress data, unit ID number, sequence number in the thickness direction, stress tensor S11, stress tensor S22, and stress tensor S12, separated by English commas; the sequence number in the thickness direction is Arabic numerals 1-5. Figure 8Take the stress of the unit ID 227 as an example, where the values ​​of stress tensor S11, stress tensor S22, and stress tensor S12 are -6.00263, -4.30525, and -1.38581 respectively. The stress tensor after writing into weld_time.inp text is expressed as

[0047] 227,1,-6.00263,-4.30525,-1.38581

[0048] 227,2,-6.00263,-4.30525,-1.38581

[0049] 227,3,-6.00263,-4.30525,-1.38581

[0050] 227,4,-6.00263,-4.30525,-1.38581

[0051] 227,5,-6.00263,-4.30525,-1.38581

[0052] Write all the unit information in weld_out.rpt into weld_time.inp in the above way to complete the creation of welding-stress text.

[0053] 8) Numerically sum the stress tensors S11, S22, and S12 with the same unit id number and the same sequence number in the thickness direction in the punching-stress text punch_time.inp and the welding-stress text weld_time.inp. Fig. 9 Taking the stress merging of unit id 227 as an example, the stress tensors S11, S22, and S12 in the punching-stress text punch_time.inp are -4.57052, -7.41900, and -3.41470, respectively. The stress tensors S11, S22, and S12 in the welding-stress text weld_time.inp are -6.00263, -4.30525, and -1.38581, respectively. The summed stress tensors S11, S22, and S12 are -1.06E+01, -1.17E+01, and -4.80E+00, respectively. Considering the five integration points in the thickness direction, the stress tensor after writing the strength-stress text is expressed as

[0054] 227,1,-1.06E+01,-1.17E+01,-4.80E+00

[0055] 227,2,-1.06E+01,-1.17E+01,-4.80E+00

[0056] 227,3,-1.06E+01,-1.17E+01,-4.80E+00

[0057] 227,4,-1.06E+01,-1.17E+01,-4.80E+00

[0058] 227,5,-1.06E+01,-1.17E+01,-4.80E+00

[0059] By using the above method, all data of the punching-stress text punch_time.inp and the welding-stress text weld_time.inp are merged to form a strength-stress text. The strength-stress text data is read by the strength analysis software, and the strength analysis of the parts is performed.

[0060] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification made to the present invention by those skilled in the art without departing from the spirit of the present invention shall fall within the protection scope of the present invention.

Claims

1. A strength testing method for simulating stamping, welding and aging processes, characterized in that: The following steps are involved: 1) Establish 5 initial finite element models, two of which are used to simulate stamping and aging, two of which are used to simulate welding and aging, and the last one is used for strength analysis; 2) Perform stamping simulation on an initial finite element model through stamping simulation software to form a stamping simulation finite element model, and derive stamping stress and node thickness data based on the stamping simulation finite element model; 3) Mapping the exported stamping stress and node thickness data to another initial finite element model through pre-processing software, and performing aging treatment on the model through strength analysis software to obtain a stamping-aging finite element model, and exporting the stress data of the stamping-aging finite element model; 4) Create a new stamping-stress text in a format that can be recognized by the strength analysis software. Write keywords at the beginning of the text and write the stress data exported from the stamping-aging finite element model in sequence; 5) Perform welding simulation on an initial finite element model through welding simulation software to form a welding simulation finite element model, and derive welding stress data based on the welding simulation finite element model; 6) Mapping the exported welding stress data to another initial finite element model through pre-processing software, and performing aging treatment on the model through strength analysis software to obtain a welding-aging finite element model, and exporting the stress data of the welding-aging finite element model; 7) Create a new welding-stress text in a format that can be recognized by the strength analysis software. Write keywords at the beginning of the text and write the stress data exported from the welding-aging finite element model in sequence; 8) The corresponding data of the stamping-stress text and the welding-stress text are combined to form a strength-stress text. The strength-stress text data is read through the strength analysis software, and the strength analysis of the parts is performed.

2. The strength testing method for simulating stamping, welding and aging processes according to claim 1 is characterized in that: The stress data derived from the stamping-aging finite element model is written into the stamping-stress text in the order of unit id number, sequence number in the thickness direction, stress tensor S11, stress tensor S22, and stress tensor S12; The stress data derived from the welding-aging finite element model is written into the stamping-stress text in the order of unit id number, sequence number in the thickness direction, stress tensor S11, stress tensor S22, and stress tensor S12.

3. The strength testing method of simulated stamping, welding and aging process according to claim 1 is characterized in that: In step 8), the corresponding data merging of the stamping-stress text and the welding-stress text refers to numerically summing the stress tensors S11, stress tensor S22, and stress tensor S12 with the same unit id number and the same serial number in the thickness direction in the stamping-stress text and the welding-stress text.

4. The strength testing method for simulating stamping, welding and aging processes according to claim 1 is characterized in that: The aging treatment comprises the following steps: a. Model stress self-balance: No load is applied to the model, so that the model can achieve stress self-balance under stress conditions; b. Set natural aging and set the field output to stress and displacement.

5. The strength testing method for simulating stamping, welding and aging processes according to claim 4 is characterized in that: The aging time for setting natural aging is 5 days.

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