A wheel fatigue life prediction method based on the critical plane method

Abstract

The application provides a belt wheel fatigue life prediction method based on an interface method, and comprises the following steps: step 1, establishing a three-dimensional model of belt transmission; step 2, simulating the operation condition of belt transmission to obtain a dangerous area of the experimental wheel during operation; step 3, performing stress analysis on the dangerous stress area to obtain stress data and determine a critical plane; and step 4, predicting the fatigue life of the experimental wheel at the critical plane through a multi-axis fatigue life prediction model Fatemi-Socie model. The technical scheme can more accurately reflect the stress condition of the belt wheel, thereby improving the precision of fatigue life prediction.

Description

Technical Field

[0001] This invention relates to the field of pulley performance prediction technology, and in particular to a method for predicting pulley fatigue life based on the critical surface method. Background Technology

[0002] With the increasing demands on pulley performance in fields such as engineering machinery, transportation, and industrial equipment, predicting pulley fatigue life has become a key technical challenge. Under actual working conditions, pulleys are often subjected to complex and variable loads; therefore, accurately predicting their fatigue life is of great significance for ensuring safe equipment operation and reducing maintenance costs.

[0003] Traditional methods for predicting the fatigue life of pulleys typically employ empirical formulas or simplified numerical models, which may lack accuracy and reliability in certain situations. Therefore, numerical simulation based on finite element analysis has gradually become an important tool for fatigue life prediction. However, the finite element method is computationally expensive when simulating large-scale, long-cycle fatigue life processes, and it struggles to meet the demands for rapid and accurate predictions in practical engineering applications.

[0004] To address this issue, the critical surface method has attracted widespread attention in fatigue life prediction in recent years. The critical surface method assesses fatigue life by analyzing the critical surface of a structure—the plane most susceptible to damage under a specific working cycle. Compared to traditional cyclic loading-based methods, this approach more closely reflects actual working conditions, more accurately captures load variation characteristics, and improves the accuracy of fatigue life prediction.

[0005] However, current research on the application of the critical surface method in pulley fatigue life prediction still faces some challenges, including how to effectively determine the critical surface and establish a suitable damage accumulation model. This invention aims to further develop the pulley fatigue life prediction method based on the critical surface method, improve its applicability and reliability in engineering practice, and provide more scientific technical support for pulley design and use. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for predicting the fatigue life of pulleys based on the critical surface method, which can more accurately reflect the stress condition of the pulleys and thus improve the accuracy of fatigue life prediction.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: a method for predicting the fatigue life of a pulley based on the critical surface method, comprising the following steps:

[0008] Step 1: Create a 3D model of the belt drive;

[0009] Step 2: Simulate the operating conditions of the belt drive to determine the danger zone when the experimental wheel is working;

[0010] Step 3: Perform stress analysis on the critical stress area to obtain stress data and determine the critical plane;

[0011] Step 4: Predict the fatigue life of the test wheel on the critical surface using the Fatemi-Socie multiaxial fatigue life prediction model.

[0012] In a preferred embodiment, in step 2, the operating conditions of the belt drive are simulated using ANSYS finite element software. The finite element simulation process includes mesh generation, boundary condition setting, setting the two sides of the belt to be in frictional contact with the pulley groove, the small pulley being the driving pulley, and the operating condition being 0s to 1s acceleration from 0RPM to 100RPM followed by uniform rotation until the experimental pulley fails.

[0013] In a preferred embodiment, the plane at a certain angle where the maximum value of the damage parameter exists is the critical plane;

[0014] The expressions for the stress and strain of the element on the critical surface are:

[0015]

[0016]

[0017] Where, σ x σ y σ z ε represents the normal stress along the direction of the coordinate value; x ε y ε z τ represents the normal strain along the direction of the coordinate value; xy τ xz τ yz γ represents the shear stress in the coordinate plane direction; xy γ xz γ yz Represents the shear strain in the coordinate plane direction;

[0018] By changing the angles θ and Φ, a new plane is determined, and a transition matrix M is established. The expression for M is:

[0019]

[0020] The stress-strain expression can be obtained by using the transition matrix:

[0021]

[0022] In a preferred embodiment, the plane with the maximum normal stress is selected as the critical plane, therefore σ n,max =3385MPa, Δγmax =3.4553E-7; The fatigue life of the pulley is predicted using the Fatemi-Socie model: The expression for the Fatemi-Socie model is:

[0023]

[0024] Where Δγ max σ represents the amplitude of the maximum shear strain on the critical plane; k represents the sensitivity of the material to the effect of stress on fatigue life; n,max σ represents the maximum normal stress on the critical plane; s Indicates yield strength; τ' f Indicates the shear fatigue strength coefficient;

[0025] N f G represents fatigue life; b0 represents shear modulus; r' represents shear fatigue strength index; f c represents the shear fatigue ductility coefficient; c0 represents the shear fatigue ductility index.

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

[0027] First, this method utilizes finite element analysis to accurately simulate the stress conditions of the pulley under actual working loads, thus accurately capturing various stress changes in its working environment. Based on this, the critical surface method is introduced. By analyzing the critical surface in the structure—the plane most susceptible to damage under a specific working cycle—the fatigue life of the pulley is evaluated. Compared to traditional methods, the critical surface method more closely reflects actual working conditions and more accurately reflects the stress state of the pulley, thereby improving the accuracy of fatigue life prediction.

[0028] This method employs mathematical and engineering models, combined with simulation data, to comprehensively consider the combined effects of multiple factors, ensuring the accurate and reasonable determination of the critical surface and providing a reliable foundation for subsequent fatigue life analysis.

[0029] On the other hand, this method also establishes the Fatemi-Socie fatigue model, which quantitatively assesses the damage degree of the pulley under actual working conditions by accumulating stress cycles on the critical surface. This model can more comprehensively and meticulously consider stress changes under different working conditions, providing a more accurate basis for the quantitative prediction of fatigue life.

[0030] In summary, the pulley fatigue life prediction method based on the critical surface method of this invention has significant advantages in practical engineering applications. By accurately capturing the stress conditions of the pulley under specific working conditions, effectively determining the critical surface, and establishing a damage accumulation model, this method provides a more scientific and feasible means of predicting fatigue life for pulley design and use, and is expected to play a key role in improving equipment reliability and reducing maintenance costs. Attached Figure Description

[0031] Figure 1 A flowchart of a preferred embodiment of the present invention;

[0032] Figure 2 This is a cloud map of the hazardous working area of ​​the spinning pulley according to a preferred embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the force on the critical surface unit body according to a preferred embodiment of the present invention. Detailed Implementation

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0036] It should be noted that the terminology used herein is for the purpose of describing particular implementations only and is not intended to limit the exemplary implementations according to this application; as used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise; furthermore, it should be understood that when the terms “comprising” and / or “including” are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0037] refer to Figure 1-3 The test was conducted using a spun pulley from a certain automobile. The pulley material is structural steel, and its mechanical properties are shown in Tables 1 and 2 below:

[0038] Table 1 Tensile and compressive fatigue parameters

[0039]

[0040] Table 2 Torsional fatigue parameters

[0041]

[0042] Step 1: Use SolidWorks software to create a 3D model of the belt drive.

[0043] Step Two: Use ANSYS finite element software to simulate the operating conditions of the belt drive and determine the critical area during the operation of the test pulley. The finite element simulation process includes mesh generation, boundary condition setting, setting the two sides of the belt to be in frictional contact with the pulley grooves, with the small pulley as the driving pulley, and the operating condition being acceleration from 0 RPM to 100 RPM from 0s to 1s, followed by uniform rotation until the test pulley fails. Through this analysis, the critical operating area of ​​the spun pulley can be accurately identified, that is, the part of the spun pulley subjected to the maximum stress and deformation during the process from start-up to uniform rotation.

[0044] Step 3: Perform stress analysis on the critical stress area to obtain stress data and determine the critical plane. The plane at a certain angle where the maximum value of the damage parameter exists is the critical plane. The expressions for the element stress and strain on the critical plane are:

[0045]

[0046]

[0047] Where, σ x σ y σ z ε represents the normal stress along the direction of the coordinate value; x ε y ε z τ represents the normal strain along the direction of the coordinate value; xy τ xz τ yz γ represents the shear stress in the coordinate plane direction; xy γ xz γ yz Represents the shear strain in the coordinate plane direction;

[0048] By changing the angles θ and Φ, a new plane is determined, and a transition matrix M is established. The expression for M is:

[0049]

[0050] The stress-strain expression can be obtained by using the transition matrix:

[0051]

[0052] The danger plane σ can be determined by finite element software calculation. x =25.411MPa; σ y =16.888MPa; σ z =19.085MPa; ε x =0.00008356; ε y =0.000052345; ε z=0.0000477; τ xy =12.363MPa; τ yz =3.447MPa; τ xz =12.536MPa; γ xy =0.0063472; γ yz =0.04236; γ xz =0.005925; therefore, the initial stress matrix is:

[0053]

[0054] The initial strain matrix is:

[0055]

[0056] By modifying the angles θ and Φ, with each modification defined as 10°, the following data can be obtained:

[0057]

[0058]

[0059] Step 4: Predict the fatigue life of the test wheel on the critical surface using the Fatemi-Socie multiaxial fatigue life prediction model.

[0060] The plane with the maximum normal stress is selected as the critical surface, therefore σ n,max =3385MPa, Δγ max =3.4553E-7

[0061] The fatigue life of the pulley was predicted using the Fatemi-Socie model:

[0062] The expression for the Fatemi-Socie model is:

[0063]

[0064] Where Δγ max σ represents the amplitude of the maximum shear strain on the critical plane; k represents the sensitivity of the material to the effect of stress on fatigue life; n,max σ represents the maximum normal stress on the critical plane; s Indicates yield strength; τ' f Indicates the shear fatigue strength coefficient;

[0065] N f G represents fatigue life; b0 represents shear modulus; r' represents shear fatigue strength index; f c represents the shear fatigue ductility coefficient; c0 represents the shear fatigue ductility index;

[0066] Substitute the following data into the Fatemi-Socie model: Δγ max =3.4553E-7; σ n,max =3385MPa;

[0067] σ s =210MPa; τ' f＝ 920MPa; G=76GPa; b0=-0.106; r' f =0.213; c0 = -0.47;

[0068] Find lnN f =11.06130377, find N f =63659.4949h, meaning that the experimental wheel will fail due to fatigue after operating under this condition for 63659.4949h.

Claims

1. A method for predicting the fatigue life of a pulley based on the critical surface method, characterized in that, Includes the following steps: Step 1: Create a 3D model of the belt drive; Step 2: Simulate the operating conditions of the belt drive to determine the danger zone when the experimental wheel is working; Step 3: Perform stress analysis on the critical stress area to obtain stress data and determine the critical plane; Step 4: Predict the fatigue life of the test wheel on the critical surface using the Fatemi-Socie multiaxial fatigue life prediction model. In step 2, the operating conditions of the belt drive are simulated using ANSYS finite element software. The finite element simulation process includes mesh generation, boundary condition setting, setting the two sides of the belt to be in frictional contact with the pulley groove, the small pulley being the driving pulley, and the operating condition being 0s to 1s from 0RPM to 100RPM followed by uniform rotation until the experimental pulley fails. The plane at a certain angle where the damage parameter has the maximum value is the critical plane; The expressions for the stress and strain of the element on the critical surface are: Where, σ x σ y σ z ε represents the normal stress along the direction of the coordinate value; x ε y ε z τ represents the normal strain along the direction of the coordinate value; xy τ xz τ yz γ represents the shear stress in the coordinate plane direction; xy γ xz γ yz Represents the shear strain in the coordinate plane direction; By changing the angles θ and Φ, a new plane is determined, and a transition matrix M is established. The expression for M is: The stress-strain expression can be obtained by using the transition matrix: 。 2. The method for predicting the fatigue life of a pulley based on the critical surface method according to claim 1, characterized in that, The plane with the maximum normal stress is selected as the critical surface, therefore σ n,max =3385MPa, ∆γ max =3.4553E-7; The fatigue life of the pulley is predicted using the Fatemi-Socie model: The expression for the Fatemi-Socie model is: Where ∆γ max This represents the magnitude of the maximum shear strain on the critical plane; k represents the sensitivity of the material to the effect of stress on fatigue life. σ n,max σ represents the maximum normal stress on the critical plane; s Indicates yield strength; τ' f Indicates the shear fatigue strength coefficient; N f G represents fatigue life; b0 represents shear modulus; b0 represents shear fatigue strength index. r' f c represents the shear fatigue ductility coefficient; c0 represents the shear fatigue ductility index.

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