Bolt strength calculation and evaluation method and device and storage medium

Abstract

The invention discloses a bolt strength calculation and evaluation method and device and a storage medium, and belongs to the technical field of commercial vehicles. The method comprises the steps that pre-tightening force is obtained; the pre-tightening force is applied to the bolt, and a whole vehicle pre-tightening working condition stress field result is obtained; obtaining the maximum value of the acceleration signal and the maximum value of the suspension displacement signal; establishing a whole vehicle vertical working condition, a braking working condition, a steering working condition and a torsion working condition based on the acceleration signal maximum value and the suspension displacement signal maximum value, and respectively substituting the whole vehicle pre-tightening working condition stress field results into the whole vehicle vertical working condition, the braking working condition, the steering working condition and the torsion working condition to obtain corresponding stress field results; and extracting the section force and the torque of the bolt from the corresponding stress field result, calculating the safety coefficient of the bolt based on the section force and the torque of the bolt, and evaluating the reliability of the bolt according to the safety coefficient. The technical problem that the bolt strength cannot be accurately calculated in the prior art can be solved.

Description

Technical Field

[0001] The present invention relates to the field of mechanical intelligent operation and maintenance technology, and in particular to a bolt strength calculation and evaluation method, device and storage medium. Background Art

[0002] Bolted connections are a crucial connection method for mechanical structures, and their structural reliability is crucial. Currently, during the product development phase, designers face limitations in verifying bolt strength. Calculations performed solely through finite element analysis (FEA) lack confidence due to uncertainties in the friction coefficient between the bolt and the connected component, as well as the bolt torque coefficient. Furthermore, theoretical verification of bolt strength cannot accurately extract the multi-directional limit loads of numerous bolts. Therefore, neither FEA nor theoretical verification of bolt strength can meet the needs of technological development.

[0003] Therefore, there is an urgent need for a bolt strength calculation and evaluation method, device and storage medium to solve the above technical problems. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method, device and storage medium for calculating and evaluating bolt strength, which can solve the technical problem that the prior art cannot accurately calculate bolt strength.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0006] In a first aspect, the present invention provides a method for calculating and evaluating bolt strength, comprising:

[0007] Obtain the preload force of the bolt and the connected parts in the actual assembly state;

[0008] Applying the pre-tightening force to the bolts in the pre-built vehicle finite element model to obtain the stress field result of the vehicle pre-tightening working condition;

[0009] Collect chassis acceleration signals and suspension displacement signals under different road conditions to obtain the maximum acceleration signal and the maximum suspension displacement signal;

[0010] Establishing the vehicle vertical working condition, braking working condition, steering working condition and torsional working condition based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, and substituting the stress field result of the vehicle preload working condition into the vehicle vertical working condition, braking working condition, steering working condition and torsional working condition respectively to obtain corresponding stress field results;

[0011] The cross-sectional force and moment of the bolt are extracted from the corresponding stress field results, the safety factor of the bolt is calculated based on the cross-sectional force and moment of the bolt, and the reliability of the bolt is evaluated according to the safety factor.

[0012] Furthermore, the friction coefficient of the contact surface between the bolt and the connected component in the actual assembly state is equal to the friction coefficient of the contact surface in the finite element model of the entire vehicle.

[0013] Furthermore, the maximum value of the acceleration signal includes a maximum vertical acceleration value, a maximum longitudinal acceleration value, and a maximum lateral acceleration value.

[0014] Furthermore, establishing the vertical working condition, braking working condition, steering working condition and torsional working condition of the entire vehicle based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal includes:

[0015] Taking the maximum vertical acceleration as the bending load, the vertical working condition of the whole vehicle is established;

[0016] Taking the maximum longitudinal acceleration as the braking load, a braking condition is established;

[0017] Let the maximum value of the lateral acceleration be the steering load to establish a steering condition;

[0018] The maximum value of the suspension displacement signal is set as a torsional working condition, and the torsional working condition is established.

[0019] Furthermore, before obtaining the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, the method further includes:

[0020] The acceleration signal and the suspension displacement signal are subjected to load editing for filtering, deburring and de-drifting.

[0021] Furthermore, calculating the safety factor of the bolt based on the cross-sectional force and moment of the bolt, and evaluating the reliability of the bolt according to the safety factor includes:

[0022] The bolt is sliced into axial equidistant sections to extract the axial force of the bolt at each section. , the resultant of the bolt tangential force , bolt torque and the bolt bending moment , based on the bolt axial force , the resultant of the bolt tangential force , bolt torque and the bolt bending moment Calculate the equivalent bolt stress:

[0023] ,

[0024] ,

[0025] ,

[0026] ,

[0027] ,

[0028] ,

[0029] ,

[0030] ,

[0031] in, is the equivalent stress of the bolt, is the stress circle area of the bolt, is the stress circle diameter of the bolt, is the bending section coefficient of the bolt, is the torsional section coefficient of the bolt, is the bending shear stress, is the torsional shear stress, is the normal stress, is the maximum shear stress of the bolt;

[0032] Calculate the anti-yield safety factor of the bolt based on the equivalent stress of the bolt:

[0033] ,

[0034] in, is the stress when the bolt undergoes 0.2% plastic deformation, is the anti-yield safety factor of the bolt;

[0035] Calculate the preload stress based on the preload force:

[0036] ,

[0037] Calculate the bolt alternating stress amplitude based on the preload stress and the bolt equivalent stress:

[0038] ,

[0039] Calculate the life stress amplitude of the bolt based on the pre-obtained nominal diameter of the bolt:

[0040] ,

[0041] The fatigue safety factor of the bolt is calculated based on the alternating stress amplitude and life stress amplitude of the bolt:

[0042] ,

[0043] Wherein, Fpre is the preload force, is the preload stress, is the bolt's alternating stress amplitude, is the life stress amplitude of the bolt, d is the nominal diameter of the bolt, is the fatigue safety factor;

[0044] Calculate the equivalent friction radius of the bolt based on the pre-obtained bolt flange surface contact diameter and the bolt flange hole diameter:

[0045] ,

[0046] in, is the equivalent friction radius of the bolt, is the bolt flange surface contact diameter, is the diameter of the bolt flange hole;

[0047] The minimum clamping force required to prevent slippage is calculated based on the resultant force of the bolt tangential force, the bolt torque, the equivalent friction radius of the bolt, and the friction coefficient of the contact surface:

[0048] ,

[0049] in, is the number of friction transmission surfaces, is the number of friction torque transmission surfaces;

[0050] According to the minimum clamping force and bolt axial force required for anti-slip Calculate the bolt's safety factor against slippage:

[0051] ,

[0052] in, The minimum clamping force required to prevent slippage, is the number of friction transmission surfaces, is the number of friction torque transmission surfaces, μ is the friction coefficient of the contact surface, is the anti-slip safety factor of the bolt;

[0053] Calculate the shear safety factor of the bolt based on the maximum shear stress of the bolt:

[0054] ,

[0055] in, is the tensile strength of the bolt, k is the ratio of the shear limit to the strength limit of the bolt, is the shear safety factor of the bolt;

[0056] According to the bolt axial force Calculate the bolt surface compressive stress:

[0057] ,

[0058] Calculate the bolt's anti-compression safety factor based on the bolt surface compressive stress:

[0059] ,

[0060] in, is the bolt surface compressive stress, is the ultimate compressive stress of the bolt, is the bolt's anti-compression safety factor;

[0061] When the anti-yield safety factor, anti-shear safety factor, anti-slip safety factor, anti-fatigue safety factor and anti-crush safety factor of all sections of the bolt are greater than 1 under the vertical working conditions, braking conditions, steering conditions and torsional conditions of the vehicle, the bolt meets the reliability requirements.

[0062] Furthermore, based on the pre-built bolt torque test fixture, repeated loading was performed according to the bolt tightening torque process requirements to obtain the original data of the bolt preload force and contact surface friction coefficient. The average bolt preload force was 75,000N and the contact surface friction coefficient was 0.15.

[0063] In a second aspect, the present invention provides a bolt strength calculation and evaluation device, characterized in that it includes:

[0064] The preload force acquisition module is used to obtain the preload force of the bolt and the connected parts in the actual assembly state;

[0065] The acceleration acquisition module is used to collect the vehicle user's road condition chassis acceleration signal and suspension displacement signal, and obtain the maximum value of the acceleration signal and the maximum value of the suspension displacement signal;

[0066] A force application module is used to apply the pre-tightening force to the middle section of the screw of the solid bolt in the pre-built finite element model of the whole vehicle to obtain the stress field result of the pre-tightening working condition of the whole vehicle;

[0067] A working condition import module is used to establish the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, and import the stress field result of the whole vehicle preload working condition into the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle respectively to obtain the corresponding stress field results;

[0068] A calculation module is used to extract the cross-sectional force and moment of the bolt from the corresponding stress field results, calculate the safety factor of the bolt based on the cross-sectional force and moment of the bolt, and evaluate the reliability of the bolt according to the safety factor.

[0069] In a third aspect, the present invention provides an electronic terminal comprising a processor and a memory connected to the processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of any of the above methods are performed.

[0070] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of any of the above methods when executed by a processor.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] The present invention applies a pre-tightening force to the middle cross-section of the screw of the solid bolt in the pre-constructed whole vehicle finite element model to obtain the stress field result of the whole vehicle pre-tightening working condition, establishes the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, and respectively brings the stress field result of the whole vehicle pre-tightening working condition into the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle to obtain corresponding stress field results; finally, extracts the cross-sectional force and moment of the bolt from the corresponding stress field results, calculates the safety factor of the bolt based on the cross-sectional force and moment of the bolt, evaluates the reliability of the bolt according to the safety factor, and can accurately calculate the bolt strength to meet the requirements for bolt reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Figure 1 1 is a flow chart of a method for calculating and evaluating bolt strength provided in the first embodiment of the present invention;

[0074] Figure 2 This is a performance analysis and evaluation flow chart of the bolt strength calculation and evaluation method provided in Example 1 of the present invention;

[0075] Figure 3 Schematic diagram of a bolt torque test fixture for the bolt strength calculation and evaluation method provided in the first embodiment of the present invention;

[0076] Figure 4 This is a schematic diagram of vehicle load collection for the bolt strength calculation and evaluation method provided in the first embodiment of the present invention;

[0077] Figure 5 This is a schematic diagram of multiple cross-sections of a bolt according to the method for calculating and evaluating bolt strength provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0078] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application. Unless there is a conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0079] The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can mean: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this document generally indicates an "or" relationship between the related objects.

[0080] VDI-2230: VDI 2230 is the authoritative standard for the systematic calculation and safety design of high-strength bolt connections developed by the Association of German Engineers (VDI). It is internationally recognized as the core specification in the field of bolt connections.

[0081] Example 1:

[0082] Figure 1 This is a flow chart of the bolt strength calculation and evaluation method in the first embodiment of the present invention. This flow chart only shows the logical sequence of the method described in this embodiment. In other possible embodiments of the present invention, different methods can be used without conflict. Figure 1 The steps shown or described are accomplished in the order shown.

[0083] The bolt strength calculation and evaluation method provided in this embodiment can be applied to a terminal and can be executed by a mechanical equipment fault identification device, which can be implemented by software and / or hardware and can be integrated into a terminal, such as any smart phone, tablet computer or computer device with communication function. Figures 1 to 5 As shown, the method of this embodiment specifically includes the following steps:

[0084] Step 1: Obtain the preload force of the bolt and the connected parts in the actual assembly state:

[0085] According to the size requirements of the bolt torque test bench and the material and surface treatment process requirements of the connected parts, the following are made: Figure 2 The bolt torque test fixture shown in the figure includes 2-1 bolt head clamping fixture, 2-2 connected parts and 2-3 test bolt group, ensuring that the connected parts are consistent with the actual state. At the same time, 10 sets of bolts of the same specification are prepared for repeated testing. During the test, 10 repeated loadings are performed according to the tightening torque process requirements of the bolts. The raw data of the bolt preload and contact surface friction coefficient shown in Table 1 can be obtained. The average bolt preload is 75000N and the contact surface friction coefficient is 0.15.

[0086]

[0087] Step 2: Establish a finite element analysis model including the vehicle body, frame, battery pack and bracket, suspension, axle and tire in advance. Among them, the components with uniform plate thickness in the vehicle body and frame system are represented by two-dimensional shell elements, and the grid size is defined as 8mm. The cab suspension, powertrain suspension, leaf spring bracket and other casting structures are represented by three-dimensional solid elements, and the grid size is defined as 5mm. The motor, gearbox, air compressor, saddle mass, etc. are simulated by the corresponding concentrated mass unit and attached to the corresponding installation position with rigid / flexible units according to the actual situation. The bolt connection is modeled by hexahedral solid unit with a grid size of 2mm. The weld is simulated by three-dimensional unit plus flexible unit. The leaf spring is simulated by two-dimensional shell unit and the shell unit thickness is adjusted to the stiffness to reach the design state. The axle is simulated by one-dimensional beam unit, as shown in the attached figure. Figure 4 As shown, including the front axle, middle axle and rear axle, the cross-sectional size and density of the beam unit are adjusted to ensure that its stiffness and mass are consistent with the actual vehicle. The tires are simulated using bar units to ensure that the vertical stiffness of the tires reaches the design state. The axle load simulation calculations are carried out under the vehicle's no-load condition. According to the actual vehicle axle load value, the analysis model is adjusted to ensure that the difference between the simulation and the actual vehicle axle is within 2%, ensuring that the simulation calculation model and the actual vehicle state are as consistent as possible.

[0088] It should be noted that the friction coefficient of the contact surface between the bolt and the connected component in the actual assembly state is equal to the friction coefficient of the contact surface in the finite element model of the entire vehicle.

[0089] The pre-tightening force is applied to the middle section of the screw rod of the bolt in the pre-built vehicle finite element model, a contact relationship between the bolt group and the connected parts is established, and the stress field result of the pre-tightening working condition of the whole vehicle is obtained.

[0090] Step 3: Carry out the whole vehicle user working condition as follows Figure 3 The vibration acceleration signal and suspension displacement signal of the vehicle frame are collected, and basic load signal processing such as filtering, deburring, and drift removal are performed on the acceleration and displacement signals. The chassis acceleration signal and suspension displacement signal under different road conditions are collected to obtain the maximum value of the acceleration signal and the maximum value of the suspension displacement signal;

[0091] The maximum value of the acceleration signal includes a maximum vertical acceleration, a maximum longitudinal acceleration, and a maximum lateral acceleration.

[0092] Step 4: Establishing the vehicle vertical working condition, braking working condition, steering working condition and torsional working condition based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal:

[0093] Taking the maximum vertical acceleration as the bending load, the vertical working condition of the whole vehicle is established;

[0094] Taking the maximum longitudinal acceleration as the braking load, a braking condition is established;

[0095] Let the maximum value of the lateral acceleration be the steering load to establish a steering condition;

[0096] The maximum value of the suspension displacement signal is set as a torsional working condition, thereby establishing a torsional working condition;

[0097] The stress field results of the vehicle preload condition are respectively brought into the vehicle vertical condition, braking condition, steering condition and torsional condition to obtain corresponding stress field results.

[0098] Step 5: Extract the cross-sectional force and moment of the bolt from the corresponding stress field results, calculate the safety factor of the bolt based on the cross-sectional force and moment of the bolt, and evaluate the reliability of the bolt according to the safety factor: It should be noted that the cross-sectional force and moment of the bolt mentioned here include: the axial force, moment and resultant force mentioned below, among which the bending moment is an independent branch of the moment, and the resultant bending moment can be obtained by calculation based on the bending moment. The specific calculation process belongs to the existing technology and will not be repeated here; Based on the bolt, 20 axial equidistant cross-sections are sliced to extract the bolt axial force of each section. , the resultant of the bolt tangential force , bolt torque and bolt bending moment , based on the bolt axial force , the resultant of the bolt tangential force , bolt torque and bolt bending moment Calculate the equivalent bolt stress:

[0099] ,

[0100] ,

[0101] ,

[0102] ,

[0103] ,

[0104] ,

[0105] ,

[0106] ,

[0107] in, is the equivalent stress of the bolt, is the stress circle area of the bolt, is the stress circle diameter of the bolt, is the bending section coefficient of the bolt, is the torsional section coefficient of the bolt, is the bending shear stress, is the torsional shear stress, is the normal stress, is the maximum shear stress of the bolt;

[0108] Calculate the anti-yield safety factor of the bolt based on the equivalent stress of the bolt:

[0109] ,

[0110] in, is the stress when the bolt undergoes 0.2% plastic deformation, obtained by looking up the VDI-2230 table. is the anti-yield safety factor of the bolt;

[0111] In this embodiment, taking the torsion condition as an example, F 轴 =65264N,F 切合 =9746N,M 合 =45126N•mm, T=3232N•mm, look up the table to get As=125mm 2 , , the anti-yield safety factor of the bolt can be calculated =1.16.

[0112] Calculate the preload stress based on the preload force:

[0113] ,

[0114] Calculate the bolt alternating stress amplitude based on the preload stress and the bolt equivalent stress:

[0115] ,

[0116] Calculate the life stress amplitude of the bolt based on the pre-obtained nominal diameter of the bolt:

[0117] ,

[0118] The fatigue safety factor of the bolt is calculated based on the alternating stress amplitude and life stress amplitude of the bolt:

[0119] ,

[0120] Wherein, Fpre is the preload force, is the preload stress, is the bolt's alternating stress amplitude, is the life stress amplitude of the bolt (the calculation formula can be found in VDI2230), d is the nominal diameter of the bolt, is the fatigue safety factor;

[0121] In this embodiment, F pre =75000N, A s =125mm 2 , =754MPa, d=14mm, the fatigue safety factor of the bolt can be obtained =0.95.

[0122] Calculate the equivalent friction radius of the bolt based on the pre-obtained bolt flange surface contact diameter and the bolt flange hole diameter:

[0123] ,

[0124] in, is the equivalent friction radius of the bolt, is the bolt flange surface contact diameter, is the diameter of the bolt flange hole;

[0125] The minimum clamping force required to prevent slippage is calculated based on the resultant force of the bolt tangential force, the bolt torque, the equivalent friction radius of the bolt, and the friction coefficient of the contact surface:

[0126] ,

[0127] in, The number of friction force transmission surfaces is the number of contact pairs of the connected parts. For example, if two plates are pressed tightly, this number is 1; if three plates are pressed tightly, this number is 2. is the number of friction torque transmission surfaces, which is set to 2.

[0128] According to the minimum clamping force and bolt axial force required for anti-slip Calculate the bolt's safety factor against slippage:

[0129] ,

[0130] in, The minimum clamping force required to prevent slippage, is the number of friction transmission surfaces, is the number of friction torque transmission surfaces, μ is the friction coefficient of the contact surface, is the anti-slip safety factor of the bolt;

[0131] In this embodiment, =9746N, =26.40mm, =15.00mm, T=3232N•mm, nf=1,nt=2,μ=0.15, we can get =0.98.

[0132] Calculate the shear safety factor of the bolt based on the maximum shear stress of the bolt:

[0133] ,

[0134] in, is the tensile strength of the bolt, k is the ratio of the shear limit to the strength limit of the bolt, is the shear safety factor of the bolt;

[0135] In this embodiment, =125mm 2 , , F 切合 =9746N, T=3232N•mm, k=0.62, the shear safety factor of the bolt can be obtained =1.87.

[0136] According to the bolt axial force Calculate the bolt surface compressive stress:

[0137] ,

[0138] Calculate the bolt's anti-compression safety factor based on the bolt surface compressive stress:

[0139] ,

[0140] in, is the bolt surface compressive stress, is the ultimate compressive stress of the bolt (can be found in VDI-2230), is the bolt's anti-compression safety factor;

[0141] In this embodiment, F 轴 =65264N,d W =26.40mm, d h =15.00mm, =900MPa, the bolt's anti-compression safety factor can be obtained =5.11.

[0142] When the anti-yield safety factor, anti-shear safety factor, anti-slip safety factor, anti-fatigue safety factor and anti-crush safety factor of all sections of the bolt are greater than 1 under the vertical working conditions, braking conditions, steering conditions and torsional conditions of the vehicle, the bolt meets the reliability requirements.

[0143] Example 2:

[0144] A second embodiment of the present invention provides a bolt strength calculation and evaluation device, comprising:

[0145] The preload force acquisition module is used to obtain the preload force of the bolt and the connected parts in the actual assembly state;

[0146] The acceleration acquisition module is used to collect the vehicle chassis acceleration signal and suspension displacement signal under user road conditions and obtain the maximum value of the acceleration signal and the maximum value of the suspension displacement signal;

[0147] A force application module is used to apply the pre-tightening force to the middle section of the screw of the solid bolt in the pre-built finite element model of the whole vehicle to obtain the stress field result of the pre-tightening working condition of the whole vehicle;

[0148] A working condition import module is used to establish the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, and import the stress field result of the whole vehicle preload working condition into the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle respectively to obtain the corresponding stress field results;

[0149] A calculation module is used to extract the cross-sectional force and moment of the bolt from the corresponding stress field results, calculate the safety factor of the bolt based on the cross-sectional force and moment of the bolt, and evaluate the reliability of the bolt according to the safety factor.

[0150] The bolt strength calculation and evaluation device provided in the second embodiment of the present invention can execute the bolt strength calculation and evaluation method provided in the first embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0151] Example 3:

[0152] The third embodiment of the present invention further provides an electronic terminal, comprising a processor and a memory connected to the processor, wherein a computer program is stored in the memory, and the processor is configured to operate according to the instructions to execute the steps of the method described in the first embodiment.

[0153] The electronic terminal provided in the third embodiment of the present invention can execute the bolt strength calculation and evaluation method provided in the first embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0154] Example 4:

[0155] Embodiment 4 of the present invention further provides a computer-readable storage medium on which a computer program is stored. When the computer program is executed by a processor, the steps of the method described in embodiment 1 are implemented, and the computer program has functional modules and beneficial effects corresponding to the execution method.

[0156] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, apparatuses, or computer program products. Therefore, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0157] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (apparatus), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0158] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0159] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0160] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for calculating and evaluating bolt strength, characterized in that: include: Obtain the preload force of the bolt and the connected parts in the actual assembly state; Applying the pre-tightening force to the bolts in the pre-built vehicle finite element model to obtain the stress field result of the vehicle pre-tightening working condition; Collect chassis acceleration signals and suspension displacement signals under different road conditions to obtain the maximum acceleration signal and the maximum suspension displacement signal; Establishing the vehicle vertical working condition, braking working condition, steering working condition and torsional working condition based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, and substituting the stress field result of the vehicle preload working condition into the vehicle vertical working condition, braking working condition, steering working condition and torsional working condition respectively to obtain corresponding stress field results; The cross-sectional force and moment of the bolt are extracted from the corresponding stress field results, the safety factor of the bolt is calculated based on the cross-sectional force and moment of the bolt, and the reliability of the bolt is evaluated according to the safety factor.

2. The bolt strength calculation and evaluation method according to claim 1, characterized in that: The friction coefficient of the contact surface between the bolt and the connected part in the actual assembly state is equal to the friction coefficient of the contact surface in the finite element model of the whole vehicle.

3. The bolt strength calculation and evaluation method according to claim 1, characterized in that: The maximum value of the acceleration signal includes a maximum vertical acceleration value, a maximum longitudinal acceleration value, and a maximum lateral acceleration value.

4. The bolt strength calculation and evaluation method according to claim 3, characterized in that: Establishing the vehicle vertical working condition, braking working condition, steering working condition and torsional working condition based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal includes: Taking the maximum vertical acceleration as the bending load, the vertical working condition of the whole vehicle is established; Taking the maximum longitudinal acceleration as the braking load, a braking condition is established; Let the maximum value of the lateral acceleration be the steering load to establish a steering condition; The maximum value of the suspension displacement signal is set as a torsional working condition, and the torsional working condition is established.

5. The bolt strength calculation and evaluation method according to claim 1, characterized in that: Before obtaining the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, the following steps are also included: The acceleration signal and the suspension displacement signal are subjected to load editing for filtering, deburring and de-drifting.

6. The bolt strength calculation and evaluation method according to claim 1, characterized in that: Calculating a safety factor of the bolt based on the cross-sectional force and moment of the bolt, and evaluating the reliability of the bolt according to the safety factor includes: The bolt is sliced into axial equidistant sections to extract the axial force of the bolt at each section. , the resultant of the bolt tangential force , bolt torque and the bolt bending moment , based on the bolt axial force , the resultant of the bolt tangential force , bolt torque and the bolt bending moment Calculate the equivalent bolt stress: ， ， ， ， ， ， ， ， in, is the equivalent stress of the bolt, is the stress circle area of the bolt, is the stress circle diameter of the bolt, is the bending section coefficient of the bolt, is the torsional section coefficient of the bolt, is the bending shear stress, is the torsional shear stress, is the normal stress, is the maximum shear stress of the bolt; Calculate the anti-yield safety factor of the bolt based on the equivalent stress of the bolt: ， in, is the stress when the bolt undergoes 0.2% plastic deformation, is the anti-yield safety factor of the bolt; Calculate the preload stress based on the preload force: ， Calculate the bolt alternating stress amplitude based on the preload stress and the bolt equivalent stress: ， Calculate the life stress amplitude of the bolt based on the pre-obtained nominal diameter of the bolt: ， The fatigue safety factor of the bolt is calculated based on the alternating stress amplitude and life stress amplitude of the bolt: ， Wherein, Fpre is the preload force, is the preload stress, is the bolt's alternating stress amplitude, is the life stress amplitude of the bolt, d is the nominal diameter of the bolt, is the fatigue safety factor; Calculate the equivalent friction radius of the bolt based on the pre-obtained bolt flange surface contact diameter and the bolt flange hole diameter: ， in, is the equivalent friction radius of the bolt, is the bolt flange surface contact diameter, is the diameter of the bolt flange hole; The minimum clamping force required to prevent slippage is calculated based on the resultant force of the bolt tangential force, the bolt torque, the equivalent friction radius of the bolt, and the friction coefficient of the contact surface: ， in, is the number of friction transmission surfaces, is the number of friction torque transmission surfaces; According to the minimum clamping force and bolt axial force required for anti-slip Calculate the bolt's safety factor against slippage: ， in, The minimum clamping force required to prevent slippage, is the number of friction transmission surfaces, is the number of friction torque transmission surfaces, μ is the friction coefficient of the contact surface, is the anti-slip safety factor of the bolt; Calculate the shear safety factor of the bolt based on the maximum shear stress of the bolt: ， in, is the tensile strength of the bolt, k is the ratio of the bolt’s shear limit to its strength limit, is the shear safety factor of the bolt; According to the bolt axial force Calculate the bolt surface compressive stress: ， Calculate the bolt's anti-compression safety factor based on the bolt surface compressive stress: ， in, is the bolt surface compressive stress, is the ultimate compressive stress of the bolt, is the bolt's anti-compression safety factor; When the anti-yield safety factor, anti-shear safety factor, anti-slip safety factor, anti-fatigue safety factor and anti-crush safety factor of all sections of the bolt are greater than 1 under the vertical working conditions, braking conditions, steering conditions and torsional conditions of the vehicle, the bolt meets the reliability requirements.

7. The method for calculating and evaluating bolt strength according to claim 2, wherein: Based on the pre-built bolt torque test fixture, repeated loading was performed according to the bolt tightening torque process requirements to obtain the original data of the bolt preload force and contact surface friction coefficient. The average bolt preload force was 75,000N and the contact surface friction coefficient was 0.

15.

8. A bolt strength calculation and evaluation device, characterized in that: include: The preload force acquisition module is used to obtain the preload force of the bolt and the connected parts in the actual assembly state; The acceleration acquisition module is used to collect the vehicle chassis acceleration signal and suspension displacement signal under user road conditions and obtain the maximum value of the acceleration signal and the maximum value of the suspension displacement signal; A force application module is used to apply the pre-tightening force to the middle section of the screw of the solid bolt in the pre-built finite element model of the whole vehicle to obtain the stress field result of the pre-tightening working condition of the whole vehicle; A working condition import module is used to establish the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle based on the maximum value of the acceleration signal and the maximum value of the suspension displacement signal, and import the stress field result of the whole vehicle preload working condition into the vertical working condition, braking working condition, steering working condition and torsional working condition of the whole vehicle respectively to obtain the corresponding stress field results; A calculation module is used to extract the cross-sectional force and moment of the bolt from the corresponding stress field results, calculate the safety factor of the bolt based on the cross-sectional force and moment of the bolt, and evaluate the reliability of the bolt according to the safety factor.

9. An electronic terminal, characterized in that: The method comprises a processor and a memory connected to the processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 7 are executed.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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