A finite element analysis method for telescopic electric pedal

Abstract

The present invention belongs to the technical field of reliability and durability of automobile accessories, and relates to a finite element analysis method for a telescopic electric pedal. The method includes: establishing a vehicle body model; establishing a telescopic pedal and a pedal motion mechanism model; establishing a finite element model of a human foot; analyzing and calculating the strength of the telescopic pedal; applying boundary conditions according to the strength working condition, analyzing and calculating the actual stress conditions of the pedal mechanism and the vehicle body under the strength working condition, and performing finite element analysis and calculation on the pedal and the vehicle body under the strength working condition, obtaining a stress cloud diagram under the strength working condition, and then comparing the analysis results with the material yield strength, and optimizing the structure of the parts that do not meet the material yield strength according to the comparison results; the present invention can accurately predict the risk of insufficient strength of the vehicle body and the pedal mechanism in the early stage of pedal development, ensure reasonable design and optimization space, avoid insufficient strength during the use of the pedal in the later stage, shorten the development cycle, reduce development costs, and improve user performance and brand quality evaluation.

Description

Technical Field

[0001] The invention belongs to the technical field of reliability and durability of automobile accessories and relates to a finite element analysis method for a telescopic electric pedal. Background Art

[0002] During the development of telescopic pedal products, engineers are concerned about whether the performance of the pedal and the performance of the connection parts with the vehicle body meet the requirements. The performance of the pedal is usually evaluated by testing, which will result in a long development cycle and high development costs. Therefore, finite element analysis is used for calculation and risk assessment before trial production, which will shorten the development cycle and reduce development costs. At present, most of the analysis of the pedal performance of brake pedals and boarding pedals uses rigid unit loading. Due to the rigidity of rigid units, the finite element analysis results under this loading method deviate from the actual results, which may lead to unreasonable structural design.

[0003] When a passenger car is in use, when the user steps on the pedal to get on the car, if the pedal mechanism is not strong enough, the weak parts of the working device will be damaged, which will greatly affect the user's overall evaluation of the vehicle and the establishment of a good brand image. Currently, there is no finite element analysis of the pedal stepping condition in the invention of the pedal.

[0004] The existing technology is to test and measure the deformation, without simulation calculation, which will lead to over-design. The existing design is a common mechanics (two-dimensional) simulation, without building a human foot (solid unit) model.

[0005] Patent CN206734187 U discloses an automatic retractable pedal structure for automobiles. In the utility model, after the bearing, bracket and bearing are installed, the sealing cover covers the outside of the bracket hole, and uses a sealing method to prevent fine particles such as mud and sand from invading the connection between the bracket and the bearing, avoiding the bearing and particles rubbing against each other inside the sleeve to make a harsh noise during rotation, avoiding the increase in the internal gap of the retractable bracket due to wear, and effectively ensuring the normal operation of the connection unit. The present invention can accurately predict the risk of insufficient strength of the vehicle body and the pedal mechanism in the early stage of pedal development, which can ensure reasonable design and optimization space, while avoiding the phenomenon of insufficient strength during the later use of the pedal, shortening the development cycle, reducing development costs, and improving user performance and brand quality evaluation.

[0006] Patent CN 112697450 A provides a reliability test system and method for automobile brake pedals. In the reliability test system and method for automobile brake pedals described in the invention, the brake system simulation device has a simple structure and powerful functions. It can meet the requirements of brake pedal reliability performance test in real vehicle state without brake disc, brake master cylinder, brake fluid, and brake oil pipe. At the same time, the test method is closer to the actual use condition of the brake pedal than the reliability test method in QC / T 788, and its performance evaluation is more comprehensive and objective. The present invention uses finite element analysis method to accurately predict the risk of insufficient strength of the vehicle body and pedal mechanism in the early stage of pedal development, ensuring reasonable design and optimization space.

[0007] Patent CN 111006881 A proposes a new type of pedal fatigue and durability test device. The method includes a drive unit mounting stand, a swing arm mounting stand and a pedal mounting stand. The new type of pedal fatigue and durability test device can solve the problem that the loading force must always be perpendicular to the pedal surface during movement and the high cost caused by the high power frequency requirements on the performance of the drive unit. The present invention directly simulates the pedaling condition through a human foot model to accurately predict the strength performance of the vehicle body and the pedal mechanism, optimizes unqualified performance in advance, reduces costs, and shortens the cycle. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the problem in the prior art that the performance of a pedal cannot be evaluated at the product design stage, and to provide a finite element analysis method for a telescopic electric pedal.

[0009] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0010] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0011] A finite element analysis method for a telescopic electric pedal, the method comprising:

[0012] Build a car body model;

[0013] Establish telescopic pedal and pedal motion mechanism model;

[0014] Establish a finite element model of the human foot;

[0015] Strength analysis and calculation of telescopic pedal.

[0016] Furthermore, the establishment of the vehicle body model includes the following contents: establishing a finite element simulation model of a part of the vehicle body, dividing each part into finite element mesh data according to three-dimensional data, and carrying out detailed modeling of the vehicle body welding points, adhesive bonding, and welding seams.

[0017] Furthermore, the establishment of the telescopic pedal and pedal motion mechanism model includes the following contents: establishing solid finite element mesh data of the telescopic pedal and the pedal motion mechanism based on the three-dimensional data; since the material thickness of the pedal and the motion mechanism is uneven, ordinary two-dimensional meshes cannot reflect the actual characteristics, so solid mesh modeling is adopted; the kinematic pairs between the pedal motion mechanisms adopt the hinge units in the ABAQUS software to simulate the motion form; a layer of shell units is covered on the surface of each pedal motion mechanism to simulate the contact force between the pedal motion mechanisms; and the pedal is in an open state during the calculation process.

[0018] Furthermore, the establishment of the finite element model of the human foot includes the following contents: using solid units to establish a sole model, two-dimensional units to establish a shoe upper, and solid units to establish a foot model. If the sole is modeled using a two-dimensional grid, the sole and the shoe upper will separate during the movement. When the sole is modeled using a solid unit, the separation phenomenon will not occur during the movement, that is, the sole is more accurately modeled using solid units. The material parameters of the sole and the shoe upper are designed according to the rubber parameters, and the foot material is designed according to the steel material.

[0019] Furthermore, the telescopic pedal strength analysis and calculation specifically includes:

[0020] Boundary conditions are imposed according to each strength condition, the actual stress conditions of the pedal mechanism and the vehicle body under each strength condition are analyzed and calculated, and finite element analysis and calculation are performed on the pedal and the vehicle body under each strength condition to obtain the stress cloud diagram under each strength condition. The analysis results are then compared with the material yield strength, and the structure of the parts that do not meet the material yield strength are optimized based on the comparison results.

[0021] Furthermore, the strength working conditions include: single-person condition - loading at 1 / 2 of the pedal, single-person condition - loading at the front 1 / 4 of the pedal, single-person condition - loading at the rear 1 / 4 of the pedal and double-person condition - loading at the front 1 / 4 and rear 1 / 4 of the pedal.

[0022] Furthermore, the specific analysis process of the single-person working condition - loading at 1 / 2 of the pedal is as follows: the body model, telescopic pedal and pedal motion mechanism model are built together according to the actual installation situation to simulate a single person standing at 1 / 2 of the pedal; all degrees of freedom of the body interception position are constrained, and a foot model of a single person's mass specified by the counterweight is placed at 1 / 2 of the pedal beam, and then a finite element analysis is performed to obtain a stress cloud diagram under this working condition, and then the analysis results are compared with the material yield strength, and the structure that does not meet the material yield strength is optimized according to the comparison results.

[0023] Furthermore, the single-person working condition - loading analysis process at the front 1 / 4 of the pedal is as follows: simulate a single person standing at the front 1 / 4 of the pedal, constrain all degrees of freedom of the body interception position, place a foot model of the single person's mass specified by the counterweight at the front 1 / 4 of the pedal beam, and then perform finite element analysis to obtain the stress cloud map under this working condition, and then compare the analysis results with the material yield strength, and optimize the structure that does not meet the material yield strength based on the comparison results.

[0024] Furthermore, the specific analysis process of the single-person working condition - the rear 1 / 4 is as follows: simulate a single person standing at the rear 1 / 4 of the pedal, constrain all degrees of freedom of the body interception position, place a foot model of the single person's mass specified by the counterweight at the rear 1 / 4 of the pedal beam, and then perform finite element analysis to obtain the stress cloud map under this working condition, and then compare the analysis results with the material yield strength, and optimize the structure that does not meet the material yield strength according to the comparison results.

[0025] Furthermore, the specific analysis process of the two-person working condition is as follows: simulate two people standing on the front 1 / 4 and rear 1 / 4 of the pedal beam, constrain all degrees of freedom of the body interception position, place the foot model of the single person's mass specified by the counterweight on the front 1 / 4 and rear 1 / 4 of the pedal beam respectively, and then perform finite element analysis and calculation to obtain the stress cloud map under this working condition, and then compare the analysis results with the material yield strength, and optimize the structure that does not meet the material yield strength according to the comparison results.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention uses a human foot model to simulate the actual situation of passengers stepping on the pedal, calculates the actual force of the pedal and the vehicle body, and provides better guidance for the design. The present invention directly simulates the working condition of passengers stepping on the pedal through a human foot model, accurately predicts the strength performance of the vehicle body and the pedal mechanism, optimizes unqualified performance in advance, reduces costs, and shortens the cycle.

[0028] 2. The present invention proposes to conduct finite element strength simulation of the pedal in combination with actual passenger usage, which ensures performance while also predicting risk points in advance. The present invention uses the finite element analysis method to accurately predict the risk of insufficient strength of the vehicle body and pedal mechanism in the early stage of pedal development, ensuring reasonable design and optimization space. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present invention will be further described below in conjunction with the accompanying drawings:

[0030] Figure 1 It is a technical roadmap of the finite element analysis method of the telescopic electric pedal described in the present invention;

[0031] Figure 2a is the pedal and pedal mechanism mesh model;

[0032] Figure 2b It is a model of a human foot;

[0033] Figure 3 This is a schematic diagram of the position of the pedal crossbeam 1 / 2 for a single person.

[0034] Figure 4 This is a schematic diagram of the position of the front 1 / 4 of the pedal beam under single-person labor conditions;

[0035] Figure 5 This is a schematic diagram of the position of the rear 1 / 4 of the pedal beam under single-person labor conditions;

[0036] Figure 6 It is a schematic diagram of the position of the front and rear 1 / 4 of the pedal beam in the double-manual condition;

[0037] Figure 7 is a single point stress distribution diagram;

[0038] Figure 8 It is an evaluation curve chart of the analysis results. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical scheme and advantages of the implementation of the present invention clearer, the technical scheme in the embodiment of the present invention will be described in more detail below in conjunction with the drawings in the embodiment of the present invention. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of the present invention, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limitations on the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The embodiments of the present invention are described in detail below in conjunction with the drawings.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the scope of protection of the present invention.

[0041] The present invention is described in detail below in conjunction with the accompanying drawings:

[0042] A finite element analysis method for a telescopic electric pedal comprises establishing a finite element model of a vehicle body, a telescopic pedal and a pedal motion mechanism; a finite element model of a human foot; analyzing and calculating the strength of the telescopic pedal; performing finite element analysis and calculation on the pedal and the vehicle body under various working conditions; obtaining a stress cloud diagram under various working conditions, and then comparing the analysis results with the yield strength of the material; and evaluating the strength of the pedal and the vehicle body.

[0043] The present invention can accurately predict the risk of insufficient strength of the vehicle body and the pedal mechanism in the early stage of pedal development, thereby ensuring reasonable design and optimization space, while avoiding the phenomenon of insufficient strength during the later use of the pedal, shortening the development cycle, reducing development costs, and improving user performance and brand quality evaluation.

[0044] The present invention discloses a finite element analysis method for a telescopic pedal, which comprises the following steps: modeling a vehicle body, a telescopic pedal and a pedal motion mechanism, and a human foot; applying boundary conditions according to various working conditions, analyzing and calculating the actual stress conditions of the pedal mechanism and the vehicle body under various working conditions, performing finite element analysis and calculation on the pedal and the vehicle body under various working conditions, obtaining stress cloud diagrams under various working conditions, and then comparing the analysis results with the material yield strength, and performing structural optimization on the parts that do not meet the material yield strength according to the comparison results.

[0045] The present invention can accurately predict the risk of insufficient strength of the vehicle body and the pedal mechanism in the early stage of pedal development, thereby ensuring reasonable design and optimization space, while avoiding the phenomenon of insufficient strength during the later use of the pedal, shortening the development cycle, reducing development costs, and improving user performance and brand quality evaluation.

[0046] To achieve the above-mentioned purpose, the present invention provides a finite element analysis method for a telescopic pedal. First, a model is established, including a vehicle body, a telescopic pedal, a pedal motion mechanism, and a human foot model. The actual stress conditions of the pedal mechanism and the vehicle body under various working conditions are calculated through strength analysis and calculation of the telescopic pedal. Finite element analysis and calculation are performed on the pedal and the vehicle body under various working conditions to obtain stress cloud diagrams under various working conditions. The analysis results are then compared with the yield strength of the material, and the structure of the parts that do not meet the yield strength of the material are optimized according to the comparison results.

[0047] The model building includes the following steps:

[0048] The model building establishes a partial car body finite element simulation model, divides each part into finite element mesh data according to three-dimensional data, and performs detailed modeling of the car body welding points, adhesive bonding, and welds;

[0049] The telescopic pedal and pedal motion mechanism adopt solid mesh. Since the material thickness of the pedal and the motion mechanism is uneven, ordinary two-dimensional mesh cannot reflect the actual characteristics, so solid mesh modeling is adopted. The kinematic pairs between the pedal motion mechanisms adopt the hinge unit in ABAQUS software to simulate the motion form. A layer of shell unit is covered on the surface of each pedal motion mechanism to simulate the contact force between the pedal motion mechanisms. The pedal is in the open state during the calculation process.

[0050] The human foot adopts solid units to build the sole model, two-dimensional units to build the upper, and solid units to build the foot model. If the sole adopts two-dimensional grid modeling, the sole and the upper will be separated during the movement. When the sole adopts Solid units modeling, the separation phenomenon will not occur during the movement, that is, the sole adopts solid units to model more accurately. The material parameters of the sole and the upper are designed according to the rubber parameters, and the foot material is designed according to the steel material.

[0051] The strength working conditions include: single-person working condition - loading at 1 / 2 of the pedal, single-person working condition - loading at the front 1 / 4 of the pedal, single-person working condition - loading at the rear 1 / 4 of the pedal and double-person working condition - loading at the front 1 / 4 and rear 1 / 4 of the pedal.

[0052] Figure 1 It is the technical roadmap of the present invention.

[0053] Step 1: Build part of the car body model.

[0054] The model building is to establish a partial car body finite element simulation model, divide each part into two-dimensional finite element mesh data according to three-dimensional data using conventional methods and mesh sizes, and use conventional simulation units to perform detailed modeling on the car body welding points, adhesive bonding, and welds;

[0055] Step 2: Build the telescopic pedal and pedal motion mechanism model.

[0056] The telescopic pedal and pedal motion mechanism adopt hexahedral grid. Due to the uneven material thickness of the pedal and the motion mechanism, ordinary two-dimensional grids cannot reflect the real characteristics, so solid hexahedral grid modeling is adopted. The kinematic pairs between the pedal motion mechanisms adopt the hinge unit in ABAQUS software to simulate the motion form. A layer of shell unit is covered on the surface of each pedal motion mechanism to simulate the contact force between the pedal motion mechanisms (contact force has various forms: tie contact, surface contact, selection of contact position, etc., and finally through multiple iterative calculations, surface contact is closer to the actual motion situation, and tie contact is inconsistent with the actual motion situation). The pedal is in the open state during the calculation process.

[0057] Step 3: Build a human foot model

[0058] The human foot adopts solid units to establish the sole model, two-dimensional units to establish the upper, and solid units to establish the foot model. If the sole adopts two-dimensional mesh modeling, the sole and the upper will be separated during the movement. When the sole adopts Solid units modeling, the separation phenomenon will not occur during the movement, that is, the sole adopts solid units modeling more accurately. The material parameters of the sole and the upper are designed according to the rubber parameters, and the foot material is designed according to the steel material.

[0059] Step 4: Strength analysis and calculation

[0060] Analysis method: The pedal system and vehicle body strength performance are evaluated through the following four working condition analysis methods. Vehicles equipped with electric telescopic pedals are all higher-level vehicles. For example, Saab shuttle buses are special agent field vehicles. When special agent field vehicles are driving, there are often special agents standing on the pedals, or lower-level vehicles are only for passengers to get on and off. Therefore, the four working conditions of this patent are determined based on the actual use of special agent vehicles and ordinary vehicles for passengers to get on and off, as well as combined with test methods.

[0061] Loading method: The conventional method uses rigid unit loading, while this patent uses shoe model loading to truly simulate the actual situation of passengers stepping on the pedals, which is more accurate and intuitive.

[0062] Single-person condition - load at 1 / 2 of the pedal, build the body, pedal and pedal mechanism model together according to the actual installation situation, and simulate a single person standing in the middle of the pedal. Constrain all degrees of freedom of the body interception position, place the foot model of the single person's mass specified by the counterweight at 1 / 2 of the pedal beam, and then perform finite element analysis to obtain the stress cloud map under this condition, and then compare the analysis results with the material yield strength. According to the comparison results, optimize the structure that does not meet the material yield strength to ensure that the pedal and body structure have sufficient strength;

[0063] Single-person condition - load the front 1 / 4 of the pedal to simulate a single person standing at the front end of the pedal. Constrain all degrees of freedom of the body interception position, place the foot model of the single person's mass specified by the counterweight at the front 1 / 4 of the pedal beam, and then perform finite element analysis to obtain the stress cloud diagram under this condition, and then compare the analysis results with the material yield strength. According to the comparison results, optimize the structure that does not meet the material yield strength to ensure that the pedal and body structure have sufficient strength;

[0064] Single-person condition - load the rear 1 / 4 of the pedal to simulate a single person standing at the rear end of the pedal. Constrain all degrees of freedom of the body interception position, place the foot model of the single person's mass specified by the counterweight at the rear 1 / 4 of the pedal beam, and then perform finite element analysis to obtain the stress cloud diagram under this condition, and then compare the analysis results with the material yield strength. According to the comparison results, optimize the structure that does not meet the material yield strength to ensure that the pedal and body structure have sufficient strength;

[0065] The two-person condition simulates two people standing at the front 1 / 4 and rear 1 / 4 of the pedal. All degrees of freedom of the body interception position are constrained, and the foot model with the weight of a single person is placed at the front 1 / 4 and rear 1 / 4 of the pedal beam respectively. Then, finite element analysis is performed to obtain the stress cloud diagram under this condition, and then the analysis results are compared with the material yield strength. According to the comparison results, the structure that does not meet the material yield strength is optimized to ensure that the pedal and body structure have sufficient strength.

[0066] The stress cloud map is a cloud map generated in the finite element software that shows the stress magnitude and distribution of each part of the mechanism under a given external force.

[0067] Finite element method is to use mathematical approximation to simulate the real physical system (geometry and load conditions). By using simple and interacting elements (i.e. units), a finite number of unknown quantities can be used to approximate the real system with infinite unknowns.

[0068] For structures, the results of finite element analysis are generally expressed in terms of von Mises stress. The stress at a point has six components, three normal stresses and three shear stresses;

[0069] The specific solution of the present invention is described in more detail below with a specific embodiment. Figure 2a , Figure 2b , Figure 3 , Figure 4 , Figure 5 The specific implementation is as follows:

[0070] Step 1: Establish a local body data model based on the body data.

[0071] Setp2: Build a human foot model, such as Figure 2a, Figure 2b shown.

[0072] The human foot adopts solid units to establish the sole model, two-dimensional units to establish the upper, and solid units to establish the foot model. If the sole adopts two-dimensional mesh modeling, the sole and the upper will be separated during the movement. When the sole adopts Solid units modeling, the separation phenomenon will not occur during the movement, that is, the sole adopts solid units modeling more accurately. The material parameters of the sole and the upper are designed according to the rubber parameters, and the foot material is designed according to the steel material.

[0073] Setp3: Build the pedal and pedal mechanism mesh model based on the pedal 3D data, such as Figure 3 shown.

[0074] Setp4: Strength analysis calculation.

[0075] Setp4.1: Single person condition - loading at 1 / 2 of the pedal, simulating a single person standing at 1 / 2 of the pedal beam, such as Figure 3 shown.

[0076] Setp4.2: Single person condition - Loading at the front 1 / 4 of the pedal, simulating a single person standing at the front 1 / 4 of the pedal beam, such as Figure 4 shown.

[0077] Setp4.3: Single person condition - Loading at 1 / 4 of the pedal, simulating a single person standing at 1 / 4 of the pedal beam. Figure 5 shown.

[0078] Setp4.4: Two-person condition, simulating two people standing at the front 1 / 4 and back 1 / 4 of the pedal. Figure 6 shown.

[0079] Strength is calculated by finite element simulation. The analysis result is von Mises stress. The stress at a point has 6 components, 3 normal stresses and 3 shear stresses. Figure 7 , Figure 8 .

[0080] Von Mises stress is equal to the following formula:

[0081]

[0082] Step 4 briefly describes the loading position of each loading condition.

[0083] In view of the comparison between the analysis results of the above working conditions and the yield strength of the material, the structure that does not meet the yield strength of the material is optimized according to the comparison results to ensure that the pedal and body structure have sufficient strength.

[0084] The analysis result of each working condition is the von Mises stress of the body and pedal mechanism. The yield strength of the material is an inherent property of the material itself and is a constant. If the four von Mises stresses analyzed from the four working conditions are all smaller than the yield strength of the material itself, it means that the pedal structure and the body structure meet the use requirements. However, if the von Mises stress value of any working condition is greater than the yield limit, it does not meet the use requirements and the unqualified structure needs to be fed back to the next professional for optimization of our analysis results, including structural optimization, material thickness optimization and material optimization.

[0085] The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any modification, equivalent replacement and improvement made by any person skilled in the art within the technical scope disclosed by the present invention and within the spirit and principle of the present invention shall be covered within the protection scope of the present invention. At the same time, the contents not described in detail in this specification belong to the prior art known to those skilled in the art.

Claims

1. A finite element analysis method for a telescopic electric step, characterized in that: The method comprises: Establishing the car body model: Establishing the finite element simulation model of part of the car body, dividing each part into finite element mesh data according to the three-dimensional data; Establishing the telescopic pedal and pedal motion mechanism model: establishing the solid finite element mesh data of the telescopic pedal and pedal motion mechanism according to the three-dimensional data; Establish a finite element model of the human foot: use solid elements to establish the sole model, two-dimensional elements to establish the upper, and solid elements to establish the foot model; Strength analysis and calculation of telescopic pedal: Boundary conditions are imposed according to various strength conditions, and the actual stress conditions of the pedal mechanism and the vehicle body under various strength conditions are analyzed and calculated. Finite element analysis and calculation are performed on the pedal and the vehicle body under various strength conditions to obtain stress cloud diagrams under various strength conditions. The analysis results are then compared with the material yield strength, and the structure of the parts that do not meet the material yield strength are optimized based on the comparison results. The strength working conditions include: single-person working condition - loading at 1 / 2 of the pedal, single-person working condition - loading at the front 1 / 4 of the pedal, single-person working condition - loading at the rear 1 / 4 of the pedal and double-person working condition - loading at the front 1 / 4 and rear 1 / 4 of the pedal; The specific analysis process of the single-person working condition - loading at 1 / 2 of the pedal is as follows: the body model, telescopic pedal and pedal motion mechanism model are built together according to the actual installation situation to simulate a single person standing at 1 / 2 of the pedal; all degrees of freedom of the body interception position are constrained, and a foot model of a single person's mass specified by the counterweight is placed at 1 / 2 of the pedal beam, and then a finite element analysis calculation is performed to obtain a stress cloud diagram under this working condition, and then the analysis results are compared with the material yield strength, and the structure that does not meet the material yield strength is optimized according to the comparison results.

2. The finite element analysis method for a telescopic electric step according to claim 1, characterized in that: The single-person working condition - loading analysis process at the front 1 / 4 of the pedal is as follows: simulate a single person standing at the front 1 / 4 of the pedal, constrain all degrees of freedom of the body interception position, place a foot model of the single person's mass specified by the counterweight at the front 1 / 4 of the pedal beam, and then perform finite element analysis to obtain a stress cloud diagram under this working condition, and then compare the analysis results with the material yield strength, and optimize the structure that does not meet the material yield strength based on the comparison results.

3. The finite element analysis method of a telescopic electric step according to claim 2, characterized in that: The specific analysis process of the single-person working condition - 1 / 4 behind the pedal is as follows: simulate a single person standing at 1 / 4 behind the pedal, constrain all degrees of freedom of the body interception position, place a foot model with a single person's mass specified by the counterweight at the back 1 / 4 of the pedal beam, and then perform finite element analysis to obtain the stress cloud map under this working condition, and then compare the analysis results with the material yield strength, and optimize the structure that does not meet the material yield strength based on the comparison results.

4. The finite element analysis method for a telescopic electric step according to claim 3 is characterized in that: The specific analysis process of the two-person working condition is as follows: simulate two people standing on the front 1 / 4 and rear 1 / 4 of the pedal beam, constrain all degrees of freedom of the body interception position, place the foot model of the single-person mass specified by the counterweight on the front 1 / 4 and rear 1 / 4 of the pedal beam respectively, and then perform finite element analysis and calculation to obtain the stress cloud map under this working condition, and then compare the analysis results with the material yield strength, and optimize the structure that does not meet the material yield strength according to the comparison results.

5. The finite element analysis method for a telescopic electric step according to claim 1, characterized in that: The establishment of the vehicle body model specifically includes the following contents: establishing a finite element simulation model of a part of the vehicle body, dividing each part into finite element mesh data according to three-dimensional data, and carrying out detailed modeling of the vehicle body welding points, adhesive bonding, and welding seams.

6. The finite element analysis method for a telescopic electric step according to claim 1, characterized in that: The establishment of the telescopic pedal and pedal motion mechanism model specifically includes the following contents: The solid finite element mesh data of the telescopic pedal and the pedal motion mechanism are established according to the three-dimensional data. The hinge unit in ABAQUS software is used to simulate the motion form of the kinematic pairs between the pedal motion mechanisms. A layer of shell elements is covered on the surface of each pedal motion mechanism to simulate the contact force between the pedal motion mechanisms. The pedal is in the open state during the calculation process.

7. The finite element analysis method for a telescopic electric step according to claim 1, characterized in that: The establishment of the human foot finite element model specifically includes the following contents: The sole model is established by solid units, the upper by two-dimensional units, and the foot model by solid units. The material parameters of the sole and upper are designed according to the rubber parameters, and the foot material is designed according to the steel material.

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