A simulation calculation method for installation and disassembly forces of a parametric structure for snap-fit ​​plastic parts in a car body.

Abstract

This invention belongs to the technical field of simulation analysis methods, specifically relating to a simulation method for the installation and disassembly forces of a parameterized structure for snap-fit ​​joints in automotive plastic parts. The method includes simulation modeling, simulation parameter setting, parameterized definition of key structural features, definition and calculation of the installation and disassembly process, plotting of installation and disassembly forces, result evaluation, and termination of the simulation process if the structural requirements are met; otherwise, the model feature parameters are adjusted, and the calculation is repeated until the structural requirements are met. This invention enables rapid adjustment of key parameters of the snap-fit ​​structure on a mesh model, efficient multi-round structural verification, and accurate and detailed verification results, including detailed disassembly forces and detailed structural damage and wear diagrams, providing a detailed and reliable basis for the development of snap-fit ​​structures for interior and exterior trim parts.

Description

Technical Field

[0001] This invention belongs to the technical field of simulation analysis methods, specifically relating to a simulation method for the installation and disassembly forces of a parameterized structure for snap-fit ​​plastic parts in a car body. Background Technology

[0002] Before molding plastic snap-fit ​​structures, an effective CAE simulation method is essential to assist development. This method can simulate the insertion and removal states without prototypes or experiments, providing a basis for product development. Existing simulation methods have the following drawbacks: First, while they can reflect the snap-fit ​​disassembly process to some extent, the accuracy differs slightly from reality. For example, the force values ​​differ significantly from actual values, and they cannot reflect the damage state after actual removal (snap-fit ​​structure failure, snap-fit ​​surface wear). Therefore, current simulation methods cannot provide reliable and realistic verification results. Second, the modeling flexibility is low. Due to the complexity of the model, fine-tuning the structure after unsatisfactory verification results requires re-meshing and redefining the model, resulting in low efficiency.

[0003] In recent years, the connection methods for automotive interior and exterior trims have been categorized into many types, such as screw connections, welding connections, riveting, and snap-fit ​​connections. Among these, snap-fit ​​connections are one of the important forms of connection between interior and exterior plastic parts. Snap-fit ​​connections mainly fall into two categories: one is a separate snap-fit ​​fixed in the structure, allowing two parts to be fastened together; the other involves matching latches and holes at both ends of the fastened parts, ensuring they are fastened together. In the development of automotive interior and exterior trims, snap-fit ​​performance is a core aspect, especially the latter type of fastening method. It must ensure that the fastening does not detach during use, while also allowing for manual disassembly (pull-out) without damaging the parts. During the development stage, before the plastic snap-fit ​​structure is molded, it is crucial to use CAE technology to simulate the installation and disassembly of the snap-fit ​​structure and evaluate its performance. This allows for the simulation of insertion and removal states without samples or testing, providing a basis for product development.

[0004] However, existing simulation methods have the following drawbacks: First, while they can reflect the buckle disassembly process to some extent, the accuracy differs slightly from reality. For example, the force value differs significantly from the actual value, and they cannot reflect the damage state after actual removal (buckle structure failure, wear of the snap-fit ​​surface). Therefore, current simulation methods cannot provide reliable and realistic verification results. Second, the modeling flexibility is low. Due to the complexity of the model, fine-tuning the structure after verification results are unsatisfactory requires re-meshing and redefining the model, resulting in low efficiency.

[0005] Currently, there are some large deformation nonlinear analysis methods that utilize detailed finite element models, but they cannot quickly adjust the key parameter characteristics of the model to meet the extremely short development period and rapid iterative development needs. The verification results cannot accurately describe the value of the disassembly force, nor can they accurately reflect the deconstruction failure. Summary of the Invention

[0006] To overcome the above problems, this invention provides a method for simulating the installation and disassembly forces of a parametric structure for snap-fit ​​joints of automotive plastic parts. This method can quickly adjust the key parameters of the snap-fit ​​structure on a mesh model, efficiently perform multiple rounds of structural verification, and obtain accurate and detailed verification results, including detailed disassembly forces, detailed structural damage and wear diagrams, etc., providing a detailed and reliable basis for the development of snap-fit ​​structures for interior and exterior trim parts.

[0007] A method for simulating the installation and disassembly forces of a parametric structure for snap-fit ​​plastic parts in a car body, comprising the following:

[0008] Step 1: Simulation Model Building

[0009] Based on the digital model of the snap-fit ​​structure, corresponding local segments are extracted and finite element meshes are generated;

[0010] First, import the geometric data files of the snap-fit ​​structure, namely the snap-fit ​​tongue and snap-fit ​​groove, into the Hypermesh software;

[0011] Second, the snap-fit ​​area of ​​the snap-fit ​​structure is cut off, the geometric data model after the cut-off is kept separately, and the rest is deleted;

[0012] Third, the extracted geometric data model is meshed.

[0013] Fourth, import the fixture mesh into hypermesh and set its connection method with the snap-fit ​​structure;

[0014] Step 2, Simulation Parameter Setting

[0015] The key parameters of the mesh model obtained in step one are set, including dynamic and static friction parameters, contact settings, material settings, property settings, measurement scheme settings, and failure characteristics settings.

[0016] First, the settings for the snap-fit ​​structure material are as follows: input the material's basic parameters, plasticity parameters, and fracture parameters;

[0017] Second, the properties of the snap-fit ​​structure are set as follows: the material property parameters of the associated structure are assigned to the entity properties;

[0018] 3. The contact settings are as follows: Define the global contact of the snap-fit ​​structure;

[0019] Fourth, the dynamic and static friction parameters are set as follows: the static friction coefficient is set to 0.2, and the sliding friction coefficient is set to 0.1.

[0020] Fifth, the measurement scheme is set as follows: select the measurement reference section passing through any one of the latch or slot as the measurement reference for the buckle installation and disassembly force;

[0021] Step 3: Define parameters for key structural features.

[0022] The key structural feature parameters of the model include the snap-fit ​​angle, height, and latch thickness, and control domains for the snap-fit ​​angle, snap-fit ​​height, and latch thickness parameters are established respectively.

[0023] Step four, defining and calculating the installation and disassembly process, includes the following steps:

[0024] First, define the static and kinematic constraints of the overall model. Define the position of the clamp fixing hole on one side as the static constraint and the position of the clamp fixing hole on the other side as the kinematic constraint. That is, the degree of freedom along the direction of the snap-fit ​​and insertion is free, and the other degrees of freedom are constrained.

[0025] Second, define the speed of the installation and disassembly process, express the speed as a displacement-time history curve, and associate this curve with the above-mentioned motion constraints;

[0026] Third, set the necessary parameters for the load step, including damping parameter settings and contact control parameter settings;

[0027] Fourth, set the output measurement reference, that is, set the disassembly force-time history output curve of the measurement reference section in step two, and set the output sampling rate of the curve; in addition, set the strain, stress, displacement, and fracture state of the output unit.

[0028] Fifth, define the load step for the buckle installation and disassembly process, and uniformly set the setting parameters in steps one through four in the load step, and set and control the minimum step size;

[0029] After completing the above settings, export the calculation file and submit it to the explicit solver in the ABAQUS software to obtain the results in odb format. The entire simulation process is then demonstrated, from which you can see whether the latch is bent, broken, or worn.

[0030] Step 5, Drawing Installation and Disassembly Forces

[0031] The calculated disassembly force-time history curve and displacement-time history curve are merged to obtain the installation and disassembly force characteristic curve, and then filtered.

[0032] Step Six: Conduct Result Evaluation

[0033] If the snap-fit ​​disassembly force meets the limit range, and the snap-fit ​​tongue is worn or not worn, and the snap-fit ​​tongue is not bent or broken, the structure is considered qualified.

[0034] If the snap-fit ​​disassembly force meets the limit range, or if the snap-fit ​​tongue is worn or not worn, or if the snap-fit ​​tongue is bent or broken, it is considered a structural defect.

[0035] If the snap-fit ​​disassembly force does not meet the limit range, the snap-fit ​​tongue is worn or not worn, or the snap-fit ​​tongue is not bent or broken, it is considered that the structure is unqualified.

[0036] If the snap-fit ​​disassembly force does not meet the limit range, the snap-fit ​​tongue is worn or not worn, or the snap-fit ​​tongue is bent or broken, it is considered a structural defect.

[0037] Step 7: If the structural qualification requirements described in Step 6 are met, the entire simulation process ends; otherwise, adjust the model feature parameters in Step 2, return to Step 3, and repeat the calculation until the structural qualification requirements described in Step 6 are met.

[0038] The snap-fit ​​area in step one refers to all areas that can come into contact during installation and disassembly.

[0039] In step one, the mesh size of all surfaces that can come into contact with the cut geometric data model during installation and disassembly is divided into 0.1mm sizes, and the mesh size of the remaining non-contact parts is divided into 1mm sizes.

[0040] In step two, the basic parameters of the material input for setting up the material include density, elastic modulus, and Poisson's ratio; the plasticity parameter is the stress-strain curve; and the fracture parameters are fracture rules, strain, and element state parameters.

[0041] In step two, the morph tool of the Hypermesh software is used to establish control domains for the parameters of card connection angle, height, and tongue thickness using the domain control card.

[0042] The installation and disassembly force drawing in step four is as follows:

[0043] First, merge the force-time history curve and the displacement-time history curve, eliminate the time axis, and obtain the disassembly force-displacement curve, which is the installation and disassembly force characteristic curve. The disassembly force value corresponding to the peak of this curve is the clamping and disassembly force.

[0044] Second, the installation and disassembly force characteristic curve is filtered to remove distorted oscillations and fluctuations.

[0045] The beneficial effects of this invention are:

[0046] The method of this invention can quickly adjust the key parameters of the snap-fit ​​structure on the mesh model, efficiently perform multiple rounds of structural verification, and obtain accurate and detailed verification results, including detailed disassembly forces, detailed structural damage and wear diagrams, etc., providing a detailed and reliable basis for the development of snap-fit ​​structures for interior and exterior trim parts. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0048] Figure 1 This is a flowchart of the present invention.

[0049] Figure 2 This is the geometric data model of the snap-fit ​​area of ​​the snap-fit ​​structure in this invention;

[0050] Figure 3 This is a schematic diagram of the measurement reference section selected for this invention.

[0051] Figure 4 This is a schematic diagram of the control domain for the tongue thickness parameter established in this invention.

[0052] Figure 5 This is a schematic diagram of the snap-fit ​​height parameter control domain established by the present invention.

[0053] Figure 6 This is a schematic diagram of the snap-fit ​​angle parameter control domain established by the present invention.

[0054] Figure 7 This is the displacement versus time history curve of the present invention.

[0055] Figure 8 This is the installation and disassembly force curve after filtering according to the present invention.

[0056] Figure 9 The diagram shows the bending and wear state of the latch structure after simulation of the present invention. Detailed Implementation

[0057] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0058] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0060] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0061] Example 1

[0062] A method for simulating the installation and disassembly forces of a parametric structure for snap-fit ​​plastic parts in a car body, comprising the following:

[0063] Step 1: Simulation Model Building

[0064] Based on the detailed digital model of the snap-fit ​​structure, corresponding local segments are extracted and finite element meshes are generated.

[0065] First, import the geometric data files of the snap-fit ​​structure, namely the snap-fit ​​tongue and snap-fit ​​groove, into the Hypermesh software;

[0066] Second, the area near the snap-fit ​​structure, namely the latch and slot (two parts), is cropped. The resulting geometric data model is retained separately, while the rest is deleted. Figure 2 As shown;

[0067] Third, mesh the extracted geometric data model in Hypermesh software;

[0068] Fourth, import the fixture mesh into the hypermesh and set its connection method with the snap-fit ​​structure; there are some specific fixed connection methods between the fixture and the part, such as bolt holes, clamping, etc. Depending on the specific situation, rigid unit coupling connection is performed in the connection area.

[0069] Step 2, Simulation Parameter Setting

[0070] The key parameters of the mesh model obtained in step one are set, including dynamic and static friction parameters, contact settings, material settings, property settings, measurement scheme settings, and failure characteristics settings.

[0071] First, for the material settings of the snap-fit ​​structure, namely the snap-fit ​​tongue and snap-fit ​​groove, the basic parameters, plasticity parameters, and fracture parameters of the material are input.

[0072] Second, the properties of the snap-fit ​​structure, namely the snap-fit ​​tongue and snap-fit ​​groove, are set as follows: the material property parameters of the associated structure are assigned to the entity properties.

[0073] 3. The contact settings are as follows: Define the global contact of the snap-fit ​​structure, namely the snap-fit ​​tongue and snap-fit ​​groove;

[0074] Fourth, the dynamic and static friction parameters are set as follows: the static friction coefficient is set to 0.2, and the sliding friction coefficient is set to 0.1.

[0075] Fifth, the measurement scheme is set as follows: Select a measurement reference section passing through either the latch or the slot (the section can be located either on the latch or on the slot, one of which is acceptable) as the measurement reference for the buckle installation and disassembly force. Figure 3 As shown; because the latch and slot components are relatively moving parts, the measurement section cannot include portions of both components simultaneously, otherwise the measurement results will be completely distorted. Only the section force containing the force of either component can accurately measure the interaction force generated by their relative motion.

[0076] Step 3: Define parameters for key structural features.

[0077] The key structural feature parameters of the model include the snap-fit ​​angle, height, and latch thickness. The parameters are defined by parametric modeling, that is, the control domains of the snap-fit ​​angle, snap-fit ​​height, and latch thickness parameters are established respectively.

[0078] Step four, defining and calculating the installation and disassembly process, includes the following steps:

[0079] The installation and disassembly process steps are set, including defining the installation and disassembly process speed, defining static and kinematic constraints, setting the necessary parameters for the load step, and setting the output measurement reference. After the settings are completed, the overall model is calculated.

[0080] First, define the static and kinematic constraints of the overall model. Define the position of the clamp fixing hole on one side as a fixed full constraint, which is a static constraint; define the position of the clamp fixing hole on the other side as a kinematic constraint, that is, the degree of freedom along the direction of the snap-fit ​​and insertion is free, and the other degrees of freedom are constrained.

[0081] Second, define the speed during the installation and disassembly process, representing the speed as a displacement versus time history curve, and then associate this curve with the aforementioned motion constraints, such as... Figure 7 As shown;

[0082] Third, set the necessary parameters for the load step, including damping parameter settings and contact control parameter settings;

[0083] Fourth, set the output measurement reference, that is, set the disassembly force-time history output curve of the measurement reference section in step two, and set the output sampling rate of the curve; in addition, set the strain, stress, displacement, and fracture state of the output unit.

[0084] Fifth, define the load step for the buckle installation and disassembly process, apply an explicit analysis algorithm to uniformly set the parameters from one to four in the load step, and set and control the minimum step size, as well as the energy card output settings;

[0085] After the above settings are completed, the calculation file is exported from the Hypermesh software preprocessing platform and submitted to the explicit solver in the ABAQUS software for calculation. The results in odb format are obtained to demonstrate the entire simulation process. From this, you can see whether the latch is bent, broken, or worn.

[0086] Step 5, Drawing Installation and Disassembly Forces

[0087] The calculated disassembly force-time history curve and displacement-time history curve are merged to obtain the installation and disassembly force characteristic curve, and then filtered.

[0088] Step six: Evaluate the results. If the requirements are met, the entire simulation process is complete. This includes the following steps:

[0089] The evaluation of the results includes three dimensions: 1. disassembly force; 2. damage to the latch structure, i.e., whether the latch is bent or broken; 3. wear of the latch, the bending and wear status of the latch structure in the calculation results are as follows: Figure 7 As shown.

[0090] The results evaluation is conducted based on the product design requirements, taking into account the above three dimensions. For example:

[0091] If the snap-fit ​​disassembly force meets the limit range, and the snap-fit ​​tongue is worn or not worn, and the snap-fit ​​tongue is not bent or broken, the structure is considered qualified.

[0092] If the snap-fit ​​disassembly force meets the limit range, or if the snap-fit ​​tongue is worn or not worn, or if the snap-fit ​​tongue is bent or broken, it is considered a structural defect.

[0093] If the snap-fit ​​disassembly force does not meet the limit range, the snap-fit ​​tongue is worn or not worn, or the snap-fit ​​tongue is not bent or broken, it is considered that the structure is unqualified.

[0094] If the snap-fit ​​disassembly force does not meet the limit range, the snap-fit ​​tongue is worn or not worn, or the snap-fit ​​tongue is bent or broken, it is considered a structural defect.

[0095] Step 7: If the structural qualification requirements described in Step 5 are met, the entire simulation process ends. Otherwise, adjust the model feature parameters in Step 2, regenerate a new feature structure simulation model, return to Step 3 to repeat the calculation, until the structural qualification requirements described in Step 5 are met.

[0096] The snap-fit ​​area in step one refers to all areas that can come into contact during installation and disassembly.

[0097] In step one, the mesh size of all surfaces that can come into contact with the cut geometric data model during installation and disassembly is divided into 0.1mm sizes, while the mesh size of the remaining non-contact parts is divided into 1mm sizes. The gradient between the contact and non-contact parts is automatically processed by the software.

[0098] In step two, the basic parameters of the material input for setting up the material include density, elastic modulus, and Poisson's ratio; the plasticity parameter is the stress-strain curve; and the fracture parameters are fracture rules, strain, and element state parameters.

[0099] In step two, the morph tool of the Hypermesh software is used to establish control domains for the structural feature parameters of the card connection angle, height, and tongue thickness using a domain control card, such as... Figure 4-6 As shown.

[0100] The installation and disassembly force drawing in step four is as follows:

[0101] First, merge the force-time history curve with the installation / disassembly speed history curve (i.e., the displacement-time history curve), eliminate the time axis, and obtain the disassembly force-displacement curve, i.e., the installation / disassembly force characteristic curve. The disassembly force value corresponding to the peak of this curve is the snap-fit ​​disassembly force.

[0102] Second, use the smooth function in Origin software to filter the installation and disassembly force characteristic curve, eliminating distorted oscillations and fluctuations, such as... Figure 8 As shown.

[0103] Example 2

[0104] 1. Simulation model building 100, including the following steps:

[0105] Based on the detailed digital model of the snap-fit ​​structure, corresponding local cuts are performed, and finite element meshes are generated.

[0106] First, import the geometric data files of the two mating parts into the Hypermesh platform;

[0107] Secondly, the area near the engagement of the two interlocking parts (the latch and the slot) is cut off. The cut-off model is kept separately, and the rest is deleted. Figure 2 As shown;

[0108] Third, the extracted geometric data is meshed. For the snap-fit ​​area, all other parts that can come into contact during installation and disassembly are divided into meshes with a size of 0.1 mm; for the remaining parts, the mesh size is divided into meshes with a size of 1 mm.

[0109] Fourth, import the fixture mesh and set the connections.

[0110] 2. Setting simulation parameters 200 includes the following steps:

[0111] For the detailed feature mesh model of the detailed snap-fit ​​structure, key parameters are set, including dynamic and static friction parameters, contact settings, material elasticity and failure characteristics settings, and parameterization of key structural feature parameters.

[0112] For the material settings of the structure (clamping tongue, clamping groove), input the basic parameters of the material (density, elastic modulus, Poisson's ratio), plastic parameters (stress-strain curve), and fracture parameters (fracture rules, strain and element state parameters);

[0113] For the setting of structural (latch, slot) properties, the material property parameters of the associated structure are assigned to the entity properties;

[0114] Regarding the contact settings, the global contact of the latch and slot structures is defined, with the static friction coefficient set to 0.2 and the sliding friction coefficient set to 0.1.

[0115] For the measurement scheme, a reference section (which can be located on either the latch or the slot) that passes through the latch and slot simultaneously is selected as the measurement reference for the buckle installation and disassembly force. Figure 3 As shown;

[0116] 3. Define model feature parameters 300, including the following steps:

[0117] The model features are defined by parameterization, which involves parameterizing and modeling key features of the model, such as snap-fit ​​angle, height, snap-fit ​​tongue thickness, etc.

[0118] Using the morph tool of the Hypermesh platform, control domains were established for structural feature parameters such as the card connection angle, height, and tongue thickness using a domain control card. For example... Figure 4-6 As shown.

[0119] 4. The installation and disassembly process is defined and calculated as follows (400), including the following steps:

[0120] The installation and disassembly process steps are set, including defining the installation and disassembly process speed, defining static and kinematic constraints, setting the necessary parameters for the load step, and setting the output measurement reference. After the settings are completed, the overall model is calculated.

[0121] First, define the static and kinematic constraints of the overall model. Define the position of the clamp fixing hole on one side as a fixed full constraint, which is the static constraint; and define the position of the clamp fixing hole on the other side as a kinematic constraint (that is, the degree of freedom is released along the direction of the snap-fit ​​and insertion movement, while the other degrees of freedom are constrained).

[0122] Secondly, the speed during installation and disassembly is defined. The speed can be represented as a displacement versus time curve. This curve is then associated with the aforementioned motion constraints, such as... Figure 7 As shown;

[0123] Third, set the necessary parameters for the load step, including damping parameter settings and contact control parameter settings;

[0124] Fourth, set the output measurement reference, that is, the force-time history output curve of the cross section in "Setting the Measurement Scheme", and set the output sampling rate of the curve; in addition, set the strain, stress, displacement, and fracture state of the output unit.

[0125] Finally, the load step for the buckle installation and disassembly process is defined. An explicit analysis algorithm is applied to uniformly set the above parameters in the load step, and necessary minimum step size settings and energy card output settings are performed.

[0126] After the above settings are completed, the Hypermesh preprocessing platform will export the calculation file and submit it for calculation.

[0127] 5. Draw a 500mm drawing for installation and disassembly forces, including the following steps:

[0128] This includes merging the calculated force-time history curve with the installation / disassembly speed history curve to obtain the installation / disassembly force characteristic curve, and then filtering it.

[0129] First, the force-time history curve and the installation / disassembly speed history curve (displacement-time history curve) are merged and processed to eliminate the time axis, resulting in the force-displacement curve, which is the installation / disassembly force curve.

[0130] Secondly, the installation and disassembly force curves obtained in the previous step are filtered to remove distorted fluctuations, such as... Figure 8 As shown.

[0131] 6. Conduct outcome evaluation 600, including the following steps:

[0132] If the requirements are met, the entire simulation process ends. The evaluation of the results mainly includes three dimensions: ① buckle disassembly force; ② damage to the latch structure (bending and fracture); ③ wear of the latch surface. The bending and wear states of the latch structure in the calculation results are as follows: Figure 9 As shown.

[0133] The results evaluation is conducted based on the product design requirements, taking into account the above three dimensions. For example:

[0134] If the snap-fit ​​disassembly force meets the limit range, the snap tongue surface is worn / unworn, and the snap tongue structure is not bent or broken, the structure is considered to be qualified.

[0135] If the snap-fit ​​disassembly force meets the limit range, the snap tongue surface is worn or not, or the snap tongue structure is bent or broken, it is considered a structural defect.

[0136] If the snap-fit ​​disassembly force does not meet the limit range, the snap tongue surface is worn / unworn, or the snap tongue structure is not bent or broken, it is considered a structural defect.

[0137] If the snap-fit ​​disassembly force does not meet the limit range, or if the snap-fit ​​tongue surface is worn, or if the snap-fit ​​tongue structure is bent or broken, it is considered a structural defect; etc.

[0138] 7. Adjust the structural feature parameter 700, including the following steps:

[0139] If the calculation results of the above steps do not meet the requirements, adjust the structural feature parameters, regenerate a new feature structure simulation model, and return to step 4 to repeat the calculation.

[0140] Adjustments to structural characteristic parameters:

[0141] First, access the Hypermesh software platform;

[0142] Secondly, the domain control card of the morph tool was used to modify the structural feature parameters such as the card angle, height, and tongue thickness, and the model features were regenerated.

[0143] Third, output the calculation file after the structure is regenerated with adjusted output parameters;

[0144] Finally, repeat steps 4, 5, and 6 to evaluate the results of this round of structural analysis.

[0145] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the scope of protection of the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, any person skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention within the scope of the technology disclosed in the present invention. These simple modifications are all within the scope of protection of the present invention.

[0146] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0147] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for simulating the installation and disassembly forces of a parametric structure for snap-fit ​​plastic parts in a car body, characterized in that... Includes the following: Step 1: Simulation Model Building Based on the digital model of the snap-fit ​​structure, corresponding local segments are extracted and finite element meshes are generated; First, import the geometric data files of the snap-fit ​​structure, namely the snap-fit ​​tongue and snap-fit ​​groove, into the Hypermesh software; Second, the snap-fit ​​area of ​​the snap-fit ​​structure is cut off, the geometric data model after the cut-off is kept separately, and the rest is deleted; Third, the extracted geometric data model is meshed. Fourth, import the fixture mesh into hypermesh and set its connection method with the snap-fit ​​structure; Step 2, Simulation Parameter Setting The key parameters of the mesh model obtained in step one are set, including dynamic and static friction parameters, contact settings, material settings, property settings, measurement scheme settings, and failure characteristics settings. First, the settings for the snap-fit ​​structure material are as follows: input the material's basic parameters, plasticity parameters, and fracture parameters; Second, the properties of the snap-fit ​​structure are set as follows: the material property parameters of the associated structure are assigned to the entity properties; 3. The contact settings are as follows: Define the global contact of the snap-fit ​​structure; Fourth, the dynamic and static friction parameters are set as follows: the static friction coefficient is set to 0.2, and the sliding friction coefficient is set to 0.

1. Fifth, the measurement scheme is set as follows: select the measurement reference section passing through any one of the latch or slot as the measurement reference for the buckle installation and disassembly force; Step 3: Define parameters for key structural features. The key structural feature parameters of the model include the snap-fit ​​angle, height, and latch thickness, and control domains for the snap-fit ​​angle, snap-fit ​​height, and latch thickness parameters are established respectively. Step four, defining and calculating the installation and disassembly process, includes the following steps: First, define the static and kinematic constraints of the overall model. Define the position of the clamp fixing hole on one side as the static constraint and the position of the clamp fixing hole on the other side as the kinematic constraint. That is, the degree of freedom along the direction of the snap-fit ​​and insertion is free, and the other degrees of freedom are constrained. Second, define the speed of the installation and disassembly process, express the speed as a displacement-time history curve, and associate this curve with the above-mentioned motion constraints; Third, set the necessary parameters for the load step, including damping parameter settings and contact control parameter settings; Fourth, set the output measurement reference, that is, set the disassembly force-time history output curve of the measurement reference section in step two, and set the output sampling rate of the curve; in addition, set the strain, stress, displacement, and fracture state of the output unit. Fifth, define the load step for the buckle installation and disassembly process, and uniformly set the setting parameters in steps one through four in the load step, and set and control the minimum step size; After completing the above settings, export the calculation file and submit it to the explicit solver in the ABAQUS software to obtain the results in odb format. The entire simulation process is then demonstrated, from which you can see whether the latch is bent, broken, or worn. Step 5, Drawing Installation and Disassembly Forces The calculated disassembly force-time history curve and displacement-time history curve are merged to obtain the installation and disassembly force characteristic curve, and then filtered. Step Six: Conduct Result Evaluation If the snap-fit ​​disassembly force meets the limit range, and the snap-fit ​​tongue is worn or not worn, and the snap-fit ​​tongue is not bent or broken, the structure is considered qualified. If the snap-fit ​​disassembly force meets the limit range, or if the snap-fit ​​tongue is worn or not worn, or if the snap-fit ​​tongue is bent or broken, it is considered a structural defect. If the snap-fit ​​disassembly force does not meet the limit range, the snap-fit ​​tongue is worn or not worn, or the snap-fit ​​tongue is not bent or broken, it is considered that the structure is unqualified. If the snap-fit ​​disassembly force does not meet the limit range, the snap-fit ​​tongue is worn or not worn, or the snap-fit ​​tongue is bent or broken, it is considered a structural defect. Step 7: If the structural qualification requirements described in Step 6 are met, the entire simulation process ends; otherwise, adjust the model feature parameters in Step 2, return to Step 3, and repeat the calculation until the structural qualification requirements described in Step 6 are met.

2. The method for simulating the installation and disassembly forces of a parameterized structure for snap-fitting plastic parts in a car body, as described in claim 1, is characterized in that... The snap-fit ​​area in step one refers to all areas that can come into contact during installation and disassembly.

3. The method for simulating the installation and disassembly forces of a parameterized structure for snap-fitting plastic parts in a car body, as described in claim 2, is characterized in that... In step one, the mesh size of all surfaces that can come into contact with the cut geometric data model during installation and disassembly is divided into 0.1mm sizes, and the mesh size of the remaining non-contact parts is divided into 1mm sizes.

4. The method for simulating the installation and disassembly forces of a parametric structure for snap-fitting plastic parts in a car body, as described in claim 3, is characterized in that... In step two, the basic parameters of the material input for setting up the material include density, elastic modulus, and Poisson's ratio; the plasticity parameter is the stress-strain curve; and the fracture parameters are fracture rules, strain, and element state parameters.

5. The method for simulating the installation and disassembly forces of a parametric structure for snap-fitting plastic parts in a car body, as described in claim 4, is characterized in that... In step two, the morph tool of the Hypermesh software is used to establish control domains for the parameters of card connection angle, height, and tongue thickness using the domain control card.

6. The method for simulating the installation and disassembly forces of a parameterized structure for snap-fitting plastic parts in a car body, as described in claim 5, is characterized in that... The installation and disassembly force drawing in step four is as follows: First, merge the force-time history curve and the displacement-time history curve, eliminate the time axis, and obtain the disassembly force-displacement curve, which is the installation and disassembly force characteristic curve. The disassembly force value corresponding to the peak of this curve is the clamping and disassembly force. Second, the installation and disassembly force characteristic curve is filtered to remove distorted oscillations and fluctuations.

Images