Finite element analysis method for evaluating structural stability of back-up roll

Abstract

The invention relates to a finite element analysis method for evaluating the stability of a supporting roller structure, belongs to the technical field of supporting roller structure stability research, and solves the problem that the stability of the supporting roller structure cannot be analyzed in the prior art. The finite element analysis method comprises the following steps: constructing a supporting roll working model, and carrying out simulation calculation based on the supporting roll working model to obtain a circumferential contact stress distribution curve and a shear stress curve of a to-be-evaluated supporting roll; performing a stress control low-cycle fatigue test and a strain control low-cycle fatigue test on the to-be-evaluated supporting roller to obtain a cyclic stress-strain curve of the to-be-evaluated supporting roller, and determining Chboch model parameters of the to-be-evaluated supporting roller based on the cyclic stress-strain curve; and applying the parameters of the Chboch model, the circumferential contact stress distribution curve and the shear stress curve to a supporting roll working model, and carrying out stability analysis on the to-be-evaluated supporting roll. And the structural stability of the supporting roll is analyzed.

Description

Technical Field

[0001] This invention relates to the field of research on the stability performance of support roller structures, and in particular to a finite element analysis method for evaluating the stability of support roller structures. Background Technology

[0002] Support rolls are core components that bear the rolling force during the rolling process of steel plates, suppress the deflection and deformation of work rolls, and ensure rolling accuracy. They are widely used in hot rolling, cold rolling, and medium and heavy plate rolling mills.

[0003] In recent years, research on support rollers has been developing towards higher load capacity, higher precision, and longer service life, which places higher demands on the fatigue and wear performance of support rollers. Therefore, based on the requirement of high load capacity, studying the stability performance of support roller structures during rolling contact is of great significance for analyzing the fatigue performance of support rollers and for the selection of materials for support rollers.

[0004] Under operating conditions, the main failure modes of support rolls are contact fatigue spalling, edge stress concentration cracks, and cracking caused by internal defects. These problems seriously affect the service life of support rolls and also lead to a reduction in rolling accuracy.

[0005] In order to study the failure mechanism of contact fatigue in support roller structure and improve its service life, there is an urgent need for an analytical method that can calculate the material stability response during the rolling contact process of support roller, so as to evaluate the fatigue performance of support roller after stabilization. Summary of the Invention

[0006] Based on the above analysis, the embodiments of the present invention aim to provide a finite element analysis method for evaluating the stability of support roller structures, in order to solve the problem that the prior art lacks analysis of the stability of support roller structures.

[0007] This invention provides a finite element analysis method for evaluating the stability of a support roller structure, the finite element analysis method comprising:

[0008] The working model of the support roll is obtained by constructing a three-dimensional finite element analysis model of the working state of the support roll under the maximum rolling force load. The circumferential contact stress distribution curve and shear stress curve of the support roll under the evaluation are obtained by simulation calculation based on the working model of the support roll.

[0009] Stress-controlled low-cycle fatigue test and strain-controlled low-cycle fatigue test were conducted on the support roller to be evaluated to obtain the cyclic stress-strain curve of the support roller to be evaluated. The Chaboche model parameters of the support roller to be evaluated were determined based on the cyclic stress-strain curve.

[0010] The Chaboche model parameters, circumferential contact stress distribution curves, and shear stress curves were applied to the working model of the support roller to perform a stability analysis of the support roller to be evaluated.

[0011] Based on the further improvement of the above finite element analysis method, the step of constructing a three-dimensional finite element analysis model of the support roll under the working state of the support roll to be evaluated according to the maximum rolling force load to obtain the working model of the support roll includes:

[0012] Construct a working roll model, a steel plate model, and a support roll model for the working state of the support roll to be evaluated;

[0013] Mesh the working roll model, steel plate model, and support roll model when evaluating the working state of the support roll;

[0014] After mesh generation, the maximum rolling force is applied to the support roll bearing housing position in a rigid motion coupling manner to simulate the working state of the support roll to be evaluated.

[0015] Based on the further improvement of the above finite element analysis method, the construction of the working roll model, steel plate model, and support roll model when the working state of the support roll to be evaluated includes:

[0016] Based on the engineering drawings of the support roller, work roller, and steel plate to be evaluated, draw the cross-sectional views of each of the support roller, work roller, and steel plate to be evaluated;

[0017] Based on the cross-sectional views of the support roller, work roller, and steel plate to be evaluated, and by rotating them 180° along their respective selected axes of symmetry, models of the work roller, steel plate, and support roller under the working state of the support roller to be evaluated are constructed.

[0018] Based on the further improvement of the above finite element analysis method, the mesh generation of the working roll model, steel plate model, and support roll model when evaluating the working state of the support roll includes:

[0019] The work roll model, steel plate model, and support roll model are divided according to the first preset length to obtain the divided work roll model, steel plate model, and support roll model.

[0020] Based on Hertz theory, the contact stress corresponding to different contact widths in the segmented work roll model, steel plate model and support roll model is determined; if the contact stress is greater than the preset stress threshold, a fine mesh is set according to the second preset length, otherwise a coarse mesh is set according to the third preset length.

[0021] The third preset length is greater than the first preset length, and the first preset length is greater than the second preset length.

[0022] Based on the further improvement of the above finite element analysis method, the circumferential contact stress distribution curve of the support roller to be evaluated, obtained by simulation calculation based on the working model of the support roller, includes:

[0023] Based on the working model of the support roller, ABAQUS calculations were performed to obtain the contact stress cloud map of the support roller to be evaluated.

[0024] Extract stress data of the circumferential distribution of contact stress along the surface of the support roller from the contact stress cloud map;

[0025] The extracted contact stress data distributed circumferentially along the surface of the support roller is fitted with the Hertz theoretical formula to obtain the circumferential contact stress distribution curve of the support roller to be evaluated.

[0026] Based on the further improvement of the above finite element analysis method, when performing stress-controlled low-cycle fatigue tests on the support roll to be evaluated, the maximum rolling force load is 1.05-1.1 times the yield stress corresponding to the material of the support roll to be evaluated.

[0027] When performing strain-controlled low-cycle fatigue tests on the support roller to be evaluated, the strain load is 0.1% higher than the strain corresponding to the yield stress of the support roller material to be evaluated.

[0028] The stress-controlled low-cycle fatigue test and the strain-controlled low-cycle fatigue test were conducted for 100 cycles, and the cyclic stress-strain curves of the support rollers were measured to evaluate them.

[0029] Based on the further improvement of the above finite element analysis method, the governing equations of the Chaboche model of the support roller to be evaluated are as follows:

[0030]

[0031] Where, σ y This represents the governing equations of the Chaboche model, where σ0 represents the initial yield stress, Q and b represent isotropic hardening material parameters, C and γ represent kinematic hardening-related material parameters, and ε... p It represents the equivalent plastic strain.

[0032] Based on the further improvement of the above finite element analysis method, the application of Chaboche model parameters, circumferential contact stress distribution curves, and shear stress curves to the working model of the support roller includes:

[0033] A small-size finite element model was constructed based on the working model of the support roller;

[0034] Using ABAQUS's Dload and Utracload functions, we obtained circumferential contact stress distribution curves and shear stress curves for multi-cycle rolling loading, respectively, to create a small-scale finite element model.

[0035] Based on the further improvement of the above finite element analysis method, the small-size finite element model adopts plane strain elements with a length of 300mm, a width of 160mm, and a minimum element size of 1μm.

[0036] Based on the further improvement of the above finite element analysis method, the stability analysis of the support roller to be evaluated includes:

[0037] Determine whether the support roller to be evaluated has yielded in the small-scale finite element model; if it has not yielded, perform only one cycle of loading; if it has yielded, perform multiple cycles of loading until the plastic strain no longer increases, at which point the support roller to be evaluated enters a stable state.

[0038] The location of the maximum equivalent stress is determined based on the stress state of the support roller under stable conditions; the inclusion defect is pre-set at the location of the maximum equivalent stress, and the stable response of the support roller under evaluation is analyzed when the defect occurs at the most dangerous location.

[0039] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0040] By constructing a three-dimensional finite element analysis model of the support roller under evaluation in its working state, the circumferential contact stress distribution curve and shear stress curve of the support roller under evaluation are simulated and calculated in the working model. Combined with the Chaboche model parameters obtained from stress-controlled low-cycle fatigue test and strain-controlled low-cycle fatigue test of the support roller under evaluation, an analysis method for the structural stability of the support roller is provided, which provides a basis for evaluating the fatigue performance of the support roller after stability and optimizing material selection.

[0041] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0042] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0043] Figure 1 A flowchart illustrating a finite element analysis method for evaluating the stability of a support roller structure, provided in an embodiment of the present invention;

[0044] Figure 2 This is a schematic diagram of the working model of the support roller provided in an embodiment of the present invention;

[0045] Figure 3 A schematic diagram showing the comparison between the circumferential contact stress distribution curve of the support roller provided in an embodiment of the present invention and the results of Hertz theory;

[0046] Figure 4 A schematic diagram of the application of the contact stress distribution function and shear stress distribution function provided in the embodiments of the present invention to a small-size finite element model;

[0047] Figure 5 This is a schematic diagram showing the results of a stability analysis of the support roller provided in an embodiment of the present invention. Detailed Implementation

[0048] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0049] A specific embodiment of the present invention discloses a finite element analysis method for evaluating the stability of a support roller structure, such as... Figure 1 As shown, the finite element analysis method includes:

[0050] Step S1: Construct a three-dimensional finite element analysis model of the support roll under the working state of the support roll to be evaluated based on the maximum rolling force load to obtain the working model of the support roll. Based on the working model of the support roll, simulate and calculate the circumferential contact stress distribution curve and shear stress curve of the support roll to be evaluated.

[0051] Step S2: Perform stress-controlled low-cycle fatigue test and strain-controlled low-cycle fatigue test on the support roller to be evaluated to obtain the cyclic stress-strain curve of the support roller to be evaluated, and determine the Chaboche model parameters of the support roller to be evaluated based on the cyclic stress-strain curve.

[0052] Step S3: Apply the Chaboche model parameters, circumferential contact stress distribution curve, and shear stress curve to the working model of the support roller to perform a stability analysis of the support roller to be evaluated.

[0053] Specifically, such as Figure 1 As shown, in step S1, the maximum rolling force load is determined in advance based on the rolling force load experienced by the support roll to be evaluated in the working state.

[0054] Specifically, such as Figure 1 As shown, in step S1, a model of the working state of the support roller to be evaluated is constructed based on the finite element analysis method to obtain the working model of the support roller.

[0055] Preferably, the step of constructing a three-dimensional finite element analysis model of the support roll under the working state of the support roll to be evaluated based on the maximum rolling force load to obtain the working model of the support roll includes:

[0056] Construct a working roll model, a steel plate model, and a support roll model for the working state of the support roll to be evaluated;

[0057] Mesh the working roll model, steel plate model, and support roll model when evaluating the working state of the support roll;

[0058] After mesh generation, the maximum rolling force is applied to the support roll bearing housing position in a rigid motion coupling manner to simulate the working state of the support roll to be evaluated.

[0059] Specifically, the working roll, steel plate, and support roll are determined when the support roll to be evaluated is in its working state, and models of the working roll, steel plate, and support roll are constructed.

[0060] Preferably, the construction of the work roll model, steel plate model, and support roll model for evaluating the working state of the support roll includes:

[0061] Based on the engineering drawings of the support roller, work roller, and steel plate to be evaluated, draw the cross-sectional views of each of the support roller, work roller, and steel plate to be evaluated;

[0062] Based on the cross-sectional views of the support roller, work roller, and steel plate to be evaluated, and by rotating them 180° along their respective selected axes of symmetry, models of the work roller, steel plate, and support roller under the working state of the support roller to be evaluated are constructed.

[0063] Specifically, the engineering drawings of the support roller, work roller, and steel plate to be evaluated are used to represent the shape and structure of the support roller, work roller, and steel plate to be evaluated. The specific format of the engineering drawings is not limited here.

[0064] Specifically, the revolution method in ABAQUS is used to construct the cross-sectional views of the support roller, work roller, and steel plate to be evaluated based on their respective engineering drawings.

[0065] Specifically, the axes of symmetry of the support roller, work roller, and steel plate to be evaluated are set in advance. After obtaining the cross-sectional views of the support roller, work roller, and steel plate to be evaluated, they are rotated 180° in combination with the pre-set selected axes of symmetry to construct the work roller model, steel plate model, and support roller model when the support roller to be evaluated is in working state.

[0066] Specifically, depending on the symmetry of the support roller, work roller, and steel plate to be evaluated, only a 1 / 4 structure or a 1 / 2 structure can be built to save on computational load.

[0067] Specifically, after constructing the working roll model, steel plate model, and support roll model for the working state of the support roll to be evaluated, the working roll model, steel plate model, and support roll model are meshed.

[0068] Preferably, the mesh generation of the work roll model, steel plate model, and support roll model when evaluating the working state of the support roll includes:

[0069] The work roll model, steel plate model, and support roll model are divided according to the first preset length to obtain the divided work roll model, steel plate model, and support roll model.

[0070] Based on Hertz theory, the contact stress corresponding to different contact widths in the segmented work roll model, steel plate model and support roll model is determined; if the contact stress is greater than the preset stress threshold, a fine mesh is set according to the second preset length, otherwise a coarse mesh is set according to the third preset length.

[0071] The third preset length is greater than the first preset length, and the first preset length is greater than the second preset length.

[0072] Specifically, the first preset length, the second preset length, and the third preset length are set in advance, and the third preset length is greater than the first preset length, and the first preset length is greater than the second preset length.

[0073] Specifically, the working roll model, steel plate model, and support roll model are first divided according to the first preset length to achieve the transition of the mesh.

[0074] Specifically, based on Hertz theory, the contact stress corresponding to different contact widths in the segmented work roll model, steel plate model, and support roll model can be determined. Based on the different contact stresses, the segmented work roll model, steel plate model, and support roll model can be further divided.

[0075] Specifically, a stress threshold is set in advance. If the contact stress exceeds the preset stress threshold, a finer mesh is set according to the second preset length; otherwise, a coarser mesh is set according to the third preset length. It is worth noting that using a small-sized finer mesh in areas with high contact stress and a coarser, larger mesh in areas far from the contact point can effectively reduce the number of elements and save computation time.

[0076] It is worth noting that during mesh generation, mesh convergence verification revealed that the contact stress converged to a stable value when the mesh size was 1 mm. Therefore, the minimum mesh size should not exceed 1 mm.

[0077] Specifically, after mesh generation, the maximum rolling force is applied to the support roll bearing housing position in a rigid motion coupling manner to simulate the working state of the support roll to be evaluated.

[0078] Specifically, the maximum rolling force is determined based on the rolling force load experienced by the support roll to be evaluated during its working state, which will not be elaborated here.

[0079] Specifically, a central reference point is established at the bearing housing of the support roll, and the central reference point is coupled to the surface of the bearing housing in a rigid motion coupling manner. Then, the maximum rolling force is applied to the central reference point, symmetrical constraints are applied on the symmetrical plane of the support roll and the work roll, and fixed constraints are applied to the lower surface of the rolled steel plate.

[0080] Specifically, such as Figure 1 As shown, in step S1, after obtaining the working model of the support roller, the circumferential contact stress distribution curve and shear stress curve of the support roller to be evaluated are obtained by simulation calculation based on the working model of the support roller.

[0081] Preferably, the circumferential contact stress distribution curve of the support roller to be evaluated, obtained by simulation calculation based on the working model of the support roller, includes:

[0082] Based on the working model of the support roller, ABAQUS calculations were performed to obtain the contact stress cloud map of the support roller to be evaluated.

[0083] Extract stress data of the circumferential distribution of contact stress along the surface of the support roller from the contact stress cloud map;

[0084] The extracted contact stress data distributed circumferentially along the surface of the support roller is fitted with the Hertz theoretical formula to obtain the circumferential contact stress distribution curve of the support roller to be evaluated.

[0085] Specifically, the stress cloud map is obtained by simulating the contact stress distribution of the support roller. The location and stress value of the point of maximum contact stress are determined from the stress cloud map. Then, the circumferential distribution of contact stress along the surface of the support roller is extracted to obtain the circumferential contact stress distribution curve of the support roller to be evaluated.

[0086] It is worth noting that the methods for obtaining the shear stress curve and the circumferential contact stress distribution curve are the same, and will not be repeated here.

[0087] Specifically, such as Figure 1 As shown, in step S1, the circumferential contact stress distribution curve and shear stress curve of the support roller to be evaluated are obtained.

[0088] Specifically, such as Figure 1 As shown, in step S2, stress-controlled low-cycle fatigue test and strain-controlled low-cycle fatigue test are performed on the support roller to be evaluated.

[0089] Preferably, when performing stress-controlled low-cycle fatigue tests on the support roll to be evaluated, the maximum rolling force load is 1.05-1.1 times the yield stress corresponding to the material of the support roll to be evaluated;

[0090] When performing strain-controlled low-cycle fatigue tests on the support roller to be evaluated, the strain load is 0.1% higher than the strain corresponding to the yield stress of the support roller material to be evaluated.

[0091] The stress-controlled low-cycle fatigue test and the strain-controlled low-cycle fatigue test were conducted for 100 cycles, and the cyclic stress-strain curves of the support rollers were measured to evaluate them.

[0092] Specifically, a stress-controlled low-cycle fatigue test is conducted on the support roll to be evaluated. The maximum rolling force load is set to be 1.05-1.1 times the yield stress corresponding to the material of the support roll to be evaluated, so that the support roll deforms, but the degree of deformation is not too large.

[0093] Specifically, when performing strain-controlled low-cycle fatigue tests on the support roller to be evaluated, the strain load is set to increase the strain corresponding to the yield stress of the support roller material by 0.1%.

[0094] Specifically, the stress-controlled low-cycle fatigue test and the strain-controlled low-cycle fatigue test were conducted for 100 cycles, and the cyclic stress-strain curves of the support rollers were measured to evaluate them.

[0095] Specifically, such as Figure 1 As shown, in step S2, the Chaboche model parameters of the support roller to be evaluated are determined based on the ring stress-strain curve.

[0096] Preferably, the governing equations of the Chaboche model for the support roller to be evaluated are:

[0097]

[0098] Where, σ y This represents the governing equations of the Chaboche model, where σ0 represents the initial yield stress, Q and b represent isotropic hardening material parameters, C and γ represent kinematic hardening-related material parameters, and ε... p It represents the equivalent plastic strain.

[0099] Specifically, the Chaboche model parameters are fitted based on the experimental results of stress-controlled low-cycle fatigue tests and strain-controlled low-cycle fatigue tests.

[0100] Specifically, the Chaboche model includes isotropic hardening and kinematic hardening components, which respectively represent the changes in yield stress and mean stress during low-cycle fatigue tests. During fitting, the changes in yield stress and back stress with cumulative plastic strain for each cycle in the two types of low-cycle fatigue tests are mainly extracted. Then, the least squares method is used to fit the curves of yield stress versus cumulative plastic strain to obtain the isotropic hardening parameters in the Chaboche model. The curves of back stress versus cumulative plastic strain are also fitted to obtain the kinematic hardening parameters in the Chaboche model.

[0101] Specifically, such as Figure 1As shown, in step S3, the circumferential contact stress distribution curve and shear stress curve obtained in step S1, together with the Chaboche model parameters obtained in step S2, are applied to the working model of the support roller to perform a stability analysis on the support roller to be evaluated.

[0102] Preferably, applying the Chaboche model parameters, circumferential contact stress distribution curve, and shear stress curve to the working model of the support roller includes:

[0103] A small-size finite element model was constructed based on the working model of the support roller;

[0104] Using ABAQUS's Dload and Utracload functions, we obtained circumferential contact stress distribution curves and shear stress curves for multi-cycle rolling loading, respectively, to create a small-scale finite element model.

[0105] Specifically, the calculation of the full-size support roller working model is not feasible due to the large number of elements and the large amount of calculation. Therefore, a small-size finite element model is adopted to effectively solve the problem of excessive calculation. The small-size model uses plane strain elements with a length of 300mm, a width of 160mm, and a minimum element size of 1μm.

[0106] Specifically, such as Figure 1 As shown, in step S3, a stability analysis is performed on the support roller to be evaluated.

[0107] It is understandable that the response of a material can be mainly divided into four states: elastic, elastically stable, plastically stable, and ratcheting effect. Under the action of cyclic contact stress, when the maximum equivalent stress value of the support roller is lower than the yield strength of the material, the material response is in the elastic state. When the maximum equivalent stress value exceeds the yield strength of the material, residual stress will be generated inside the support roller, and the material will also undergo work hardening. Under the interaction of these two factors, the subsequent local material response of the support roller will continue to exhibit an elastic state, which is elastically stable. When the contact stress continues to increase, the subsequent cyclic stress-strain curve, although it cannot enter the elastic state, will always remain closed. The response in this stage is called the plastically stable state. When the load continues to increase and the equivalent stress exceeds the plastic stability limit, the cyclic stress-strain curve will show a non-closed phenomenon, and the response at this time is manifested as the ratcheting effect.

[0108] Preferably, the stability analysis of the support roller to be evaluated includes:

[0109] Determine whether the support roller to be evaluated has yielded in the small-scale finite element model; if it has not yielded, perform only one cycle of loading; if it has yielded, perform multiple cycles of loading until the plastic strain no longer increases, at which point the support roller to be evaluated enters a stable state.

[0110] The location of the maximum equivalent stress is determined based on the stress state of the support roller under stable conditions; the inclusion defect is pre-set at the location of the maximum equivalent stress, and the stable response of the support roller under evaluation is analyzed when the defect occurs at the most dangerous location.

[0111] Specifically, since there are different types of inclusion defects inside the support roller, the stability analysis must consider not only the material response when there are no defects, but also the stability analysis when inclusion defects are present.

[0112] The stability analysis is performed on a small-scale finite element model. First, a stability analysis is performed when there are no defects to determine whether the support roller to be evaluated yields in the small-scale finite element model. If no yielding occurs, only one cycle of loading is performed. If yielding occurs, multiple cycles of loading are performed until the plastic strain no longer increases. At this point, the support roller to be evaluated enters a stable state.

[0113] Specifically, a stable response to inclusion defects is performed in a stable state.

[0114] Specifically, the inclusion defects are pre-positioned at the location of maximum equivalent stress, and the stability response of the support roller to be evaluated is analyzed when the defect occurs at the most dangerous location.

[0115] The following specific embodiment will further illustrate the finite element analysis method for evaluating the stability of a support roller structure provided by the present invention.

[0116] I. Establish a three-dimensional finite element analysis model of the support roller during operation.

[0117] A working model of the support roller was established using the commercial finite element analysis software ABAQUS. The model was then meshed, and calculations were performed to determine the loading and contact settings. The specific steps are as follows:

[0118] 1) The three-dimensional solid model of the support roll is created using the revolution method in ABAQUS. First, the cross-sectional view of the support roll is drawn in the sketch operation interface according to the engineering drawing of the support roll. Then, the axis of symmetry is selected and rotated 180° to create a three-dimensional solid model of the support roll. Here, only 1 / 4 of the structure is created to save computation due to the symmetry of the support roll. Similarly, the work roll model and the three-dimensional model of the rolled steel plate are created in the same way.

[0119] 2) Before meshing, the support roller model is split to achieve mesh transition. The purpose of splitting is to use a small-sized fine mesh in areas with high contact stress and a coarser, larger mesh in areas far from the contact position. This can effectively reduce the number of elements and save computation time.

[0120] 3) Establish a center reference point at the bearing housing of the support roll and couple the center reference point to the surface of the bearing housing in a rigid motion coupling manner. Then apply the maximum rolling force load to the center reference point, apply symmetrical constraints on the symmetrical plane of the support roll and the work roll, and apply fixed constraints on the lower surface of the rolled steel plate.

[0121] The obtained working model of the support roller is as follows Figure 2 As shown.

[0122] 2. Determine the circumferential contact stress distribution curve and shear stress curve.

[0123] The contact stress distribution of the support roller is obtained through simulation calculation. The location and stress value of the maximum contact stress point are determined from the stress cloud diagram. Then, the circumferential distribution curve of the contact stress along the surface of the support roller is extracted to obtain the contact stress distribution function.

[0124] The fitting results show that the distribution of contact stress on the support rollers agrees well with Hertz theory. Therefore, Hertz theory formulas were used for the fitting, and the results are as follows. Figure 3 As shown.

[0125] Similarly, the shear stress function of the support roller can be obtained.

[0126] 3. Write subroutines for contact stress and shear stress to achieve cyclic rolling loading on the surface of a small-sized model.

[0127] Complete the subroutine writing and establish the small-scale finite element model. The specific steps are as follows:

[0128] 1) ABAQUS provides two interfaces for defining distributed loads: Dload and Utracload. These two interfaces can be used to effectively define various types of distributed loads, including surface contact stress and shear stress.

[0129] Using the contact stress distribution function obtained from step two, this function is programmed into two subroutines. Dload is used to apply cyclic contact stress, and Utracload is used to apply surface friction shear stress, as follows: Figure 4 As shown.

[0130] After writing the two subroutines, save them in a .for file. Then, select the loading method for the distributed load and select the loading location, which is located on the upper surface of the small sample model. Finally, when submitting the calculation, select the working path of the subroutines and associate them.

[0131] 2) In the calculation of the full-size support roller model, due to the large number of elements and the high computational cost, multi-cycle rolling loading is not feasible. Therefore, establishing a small-size finite element model can effectively solve the problem of excessive computational cost. The small-size model uses plane strain elements, with a model length of 300mm, a width of 160mm, and a minimum element size of 1μm.

[0132] IV. Conduct low-cycle fatigue testing and fit the material parameters required for stability analysis.

[0133] Stress-controlled and strain-controlled low-cycle fatigue tests were conducted on the support rollers to obtain their cyclic stress-strain curves. Then, based on the test results, the parameters of the cyclic constitutive model, namely the Chaboche model, were fitted. The model includes isotropic hardening and kinematic hardening components, which represent the changes in fatigue stress amplitude and mean stress, respectively. Therefore, during the fitting process, the curves of stress amplitude and back stress with cumulative plastic strain in strain-controlled low-cycle fatigue were mainly extracted, and then the model parameters were fitted.

[0134] The governing equations of the Chaboche model are:

[0135]

[0136] In the model: Q and b are isotropically strengthened material parameters, σ0 is the initial yield stress; ε p It is the equivalent plastic strain, and C and γ are material parameters related to kinematic hardening.

[0137] 5. Pre-inspect material defects and conduct stability analysis of support roller materials.

[0138] Because there are different types of inclusion defects inside the support roller, the stability analysis must consider not only the material response when there are no defects, but also the stability analysis when there are inclusion defects. The stability analysis is completed on a small-scale finite element model.

[0139] First, a stability analysis is performed under defect-free conditions to determine the response of the support roller. Then, based on the stable stress state, the location of the maximum equivalent stress is determined. Inclusion defects are pre-positioned at the location of maximum equivalent stress to analyze the material's stability response when defects occur at the most critical location. The results are as follows: Figure 5 As shown.

[0140] The response of materials is mainly classified into four states: elastic, elastically stable, plastically stable, and ratcheting effect. Under the action of cyclic contact stress, when the maximum equivalent stress value of the support roller is lower than the yield strength of the material, the material response is in the elastic state. When the maximum equivalent stress value exceeds the yield strength of the material, residual stress will be generated inside the support roller, and the material will also undergo work hardening. Under the interaction of these two factors, the subsequent local material response of the support roller will continue to exhibit an elastic state, which is elastically stable. When the contact stress continues to increase, the subsequent cyclic stress-strain curve, although it cannot enter the elastic state, will always remain closed. The response in this stage is called the plastically stable state. When the load continues to increase and the equivalent stress exceeds the plastic stability limit value, the cyclic stress-strain curve will show a non-closed phenomenon, and the response at this time is manifested as the ratcheting effect.

[0141] Compared with existing technologies, the finite element analysis method for evaluating the structural stability of a support roller provided in this invention constructs a three-dimensional finite element analysis model of the support roller under working conditions. The circumferential contact stress distribution curve and shear stress curve of the support roller under evaluation are simulated and calculated within the working model. Combined with the Chaboche model parameters obtained from stress-controlled low-cycle fatigue tests and strain-controlled low-cycle fatigue tests, this method provides an analytical approach for the structural stability of the support roller, laying the foundation for evaluating the fatigue performance of the support roller after stabilization and optimizing material selection.

[0142] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware, and the program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0143] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A finite element analysis method for evaluating the stability of a support roller structure, characterized in that, The finite element analysis method includes: The working model of the support roll is obtained by constructing a three-dimensional finite element analysis model of the working state of the support roll under the maximum rolling force load. The circumferential contact stress distribution curve and shear stress curve of the support roll under the evaluation are obtained by simulation calculation based on the working model of the support roll. Stress-controlled low-cycle fatigue test and strain-controlled low-cycle fatigue test were conducted on the support roller to be evaluated to obtain the cyclic stress-strain curve of the support roller to be evaluated. The Chaboche model parameters of the support roller to be evaluated were determined based on the cyclic stress-strain curve. The Chaboche model parameters, circumferential contact stress distribution curves, and shear stress curves were applied to the working model of the support roller to perform a stability analysis of the support roller to be evaluated.

2. The finite element analysis method according to claim 1, characterized in that, The process of constructing a three-dimensional finite element analysis model of the support roll under the working state of the support roll to be evaluated based on the maximum rolling force load to obtain the working model of the support roll includes: Construct a working roll model, a steel plate model, and a support roll model for the working state of the support roll to be evaluated; Mesh the working roll model, steel plate model, and support roll model when evaluating the working state of the support roll; After mesh generation, the maximum rolling force is applied to the support roll bearing housing position in a rigid motion coupling manner to simulate the working state of the support roll to be evaluated.

3. The finite element analysis method according to claim 2, characterized in that, The construction of the working roll model, steel plate model, and support roll model for evaluating the working state of the support roll includes: Based on the engineering drawings of the support roller, work roller, and steel plate to be evaluated, draw the cross-sectional views of each of the support roller, work roller, and steel plate to be evaluated; Based on the cross-sectional views of the support roller, work roller, and steel plate to be evaluated, and by rotating them 180° along their respective selected axes of symmetry, models of the work roller, steel plate, and support roller under the working state of the support roller to be evaluated are constructed.

4. The finite element analysis method according to claim 2, characterized in that, The mesh generation of the work roll model, steel plate model, and support roll model when evaluating the working state of the support roll includes: The work roll model, steel plate model, and support roll model are divided according to the first preset length to obtain the divided work roll model, steel plate model, and support roll model. Based on Hertz theory, the contact stress corresponding to different contact widths in the segmented work roll model, steel plate model and support roll model is determined; if the contact stress is greater than the preset stress threshold, a fine mesh is set according to the second preset length, otherwise a coarse mesh is set according to the third preset length. The third preset length is greater than the first preset length, and the first preset length is greater than the second preset length.

5. The finite element analysis method according to claim 1, characterized in that, The circumferential contact stress distribution curve of the support roller to be evaluated, obtained by simulation calculation based on the working model of the support roller, includes: Based on the working model of the support roller, ABAQUS calculations were performed to obtain the contact stress cloud map of the support roller to be evaluated. Extract stress data of the circumferential distribution of contact stress along the surface of the support roller from the contact stress cloud map; The extracted contact stress data distributed circumferentially along the surface of the support roller is fitted with the Hertz theoretical formula to obtain the circumferential contact stress distribution curve of the support roller to be evaluated.

6. The finite element analysis method according to claim 1, characterized in that, When performing stress-controlled low-cycle fatigue tests on the support roll to be evaluated, the maximum rolling force load is 1.05-1.1 times the yield stress corresponding to the material of the support roll to be evaluated; When performing strain-controlled low-cycle fatigue tests on the support roller to be evaluated, the strain load is 0.1% higher than the strain corresponding to the yield stress of the support roller material to be evaluated. The stress-controlled low-cycle fatigue test and the strain-controlled low-cycle fatigue test were conducted for 100 cycles, and the cyclic stress-strain curves of the support rollers were measured to evaluate them.

7. The finite element analysis method according to claim 6, characterized in that, The governing equations of the Chaboche model for the support roller to be evaluated are: Where, σ y This represents the governing equations of the Chaboche model, where σ0 represents the initial yield stress, Q and b represent isotropic hardening material parameters, C and γ represent kinematic hardening-related material parameters, and ε... p It represents the equivalent plastic strain.

8. The finite element analysis method according to claim 1, characterized in that, The application of Chaboche model parameters, circumferential contact stress distribution curves, and shear stress curves to the working model of the support roller includes: A small-size finite element model was constructed based on the working model of the support roller; Using ABAQUS's Dload and Utracload functions, we obtained circumferential contact stress distribution curves and shear stress curves for multi-cycle rolling loading, respectively, to create a small-scale finite element model.

9. The finite element analysis method according to claim 8, characterized in that, The small-size finite element model uses plane strain elements with a length of 300 mm, a width of 160 mm, and a minimum element size of 1 μm.

10. The finite element analysis method according to claim 8, characterized in that, The stability analysis of the support roller to be evaluated includes: Determine whether the support roller to be evaluated has yielded in the small-scale finite element model; if it has not yielded, perform only one cycle of loading; if it has yielded, perform multiple cycles of loading until the plastic strain no longer increases, at which point the support roller to be evaluated enters a stable state. The location of the maximum equivalent stress is determined based on the stress state of the support roller under stable conditions; the inclusion defect is pre-set at the location of the maximum equivalent stress, and the stable response of the support roller under evaluation is analyzed when the defect occurs at the most dangerous location.

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