Wear analysis method of sliding bearings based on wear mechanism and adaptive grid algorithm

Abstract

The invention belongs to the technical field of bearing wear analysis, and provides a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm, and the steps include: S1, obtaining the structure, material and operating condition information of the sliding bearing; S2, establishing a sliding bearing finite element model, and meshing the model by using an ALE adaptive grid algorithm; S3, establishing a sliding bearing wear sub-model; S4, associating the sliding bearing wear sub-model with a main model in the form of a subroutine; S5, outputting the displacement field of each grid node of the wear contact surface; S6, generating a wear amount distribution field map based on the displacement field of each grid node of the wear contact surface, and evaluating the wear concentration area. The invention adopts a sliding bearing surface wear amount calculation model combined with an ALE adaptive grid algorithm, obtains the relationship between the wear rate and the contact force through experiments, and obtains the sliding bearing model by fitting, simulates the contour change caused by the wear on the bearing surface in the model by using the ALE adaptive grid algorithm, and predicts the friction damage of the sliding bearing.

Description

Technical Field

[0001] The invention belongs to the technical field of bearing wear analysis, and in particular relates to a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm. Background Art

[0002] Sliding bearings are widely used in high-speed rotating machinery such as gear pumps, centrifugal pumps, compressors, etc. During the working process, due to the long-term radial load and tangential relative sliding on the inner surface, they are prone to wear and failure. The wear of sliding bearings may cause the rotating machinery to fail suddenly, resulting in serious safety accidents.

[0003] There are two main problems with the existing sliding bearing analysis methods: first, there is a lack of accurate wear mechanism models, and only some empirical wear coefficients can be used as reference, which cannot accurately quantify the relationship between wear and bearing contact stress and sliding speed; second, it assumes that wear damage is linearly accumulated, ignoring the mutual influence between wear and contact stress, which affects the accuracy of the analysis. Therefore, it is necessary to propose a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention proposes a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm, which adopts a sliding bearing surface wear calculation model combined with the ALE adaptive grid algorithm, and obtains the relationship between material wear rate and contact force through experiments to obtain the sliding bearing finite element main model, and simulates the contour changes caused by wear on the bearing surface and the influence on stress distribution in the sliding bearing model through the ALE adaptive grid algorithm, thereby realizing the coupled iterative solution of "current cycle wear calculation → wear contour change → stress distribution change → next cycle wear calculation", and realizing the prediction of sliding bearing wear.

[0005] The present invention provides a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm, which comprises the following steps:

[0006] S1. Obtain information about sliding bearings, materials and operating conditions;

[0007] S2, establishing a main finite element model of the sliding bearing, and using the ALE adaptive mesh algorithm to mesh the main finite element model of the sliding bearing;

[0008] S3. Establish a sliding bearing wear sub-model, specifically including:

[0009] S31. Within the incremental step number M, the contact stress field of the bearing wear contact surface obtained by the main finite element model of the sliding bearing is used as input, and the wear amount of each grid node on the bearing wear contact surface is obtained by fitting the test data:

[0010] Δh=8.24×10 -11 P 0.184 vΔt

[0011] Where P is the contact stress of the mesh node, v is the relative sliding velocity between the bearing and the spindle, and Δt is the current time increment;

[0012] S32, update the local coordinates n of the mesh nodes of the wear contact surface A , the grid update direction in the local coordinate system is the normal of the wear contact surface, and the local coordinate u3 of the normal direction of the grid node i is updated according to the adjacent grid node i-1 as follows:

[0013] u3 (i) ←u3 (i-1) -Δh

[0014] S33, after the grid node coordinates are updated, the global grid is scanned, and after the grid scan is completed, each grid node is repositioned;

[0015] S34. In the main finite element model of the sliding bearing, a mesh node B needs to be selected for the target mesh node A located at the edge of the wear contact surface, and the coordinates of the target mesh node A are updated by the global coordinates (x1, x2, x3) of the mesh node B, specifically:

[0016]

[0017] Δh=[Δh1,Δh2,Δh3] T

[0018] u (i) ←u (i-1) +M trans ·Δh

[0019] Among them, u (i) =[u1,u2,u3] T , M trans is the transformation matrix between the local coordinate system and the global coordinate system. The direction of the local coordinate system is related to the mesh topology. trans Obtained through finite element software;

[0020] S4, based on Fortran language programming, the sliding bearing wear sub-model is associated with the sliding bearing finite element main model in the form of a subroutine;

[0021] S5. Setting a loading-wear-unloading analysis step in the finite element main model of the sliding bearing, setting the rotation speed and the working condition information of the radial load on the sliding bearing, completing the numerical calculation of the analysis step according to the preset number of runs, and outputting the displacement field of each mesh node of the wear contact surface of the sliding bearing;

[0022] S6. Based on the displacement field of each grid node of the wear contact surface of the sliding bearing, a wear distribution field diagram of the sliding bearing is generated to determine the concentrated wear area of ​​the sliding bearing.

[0023] Preferably, the structural information of the sliding bearing in step S1 includes the sliding bearing and an assembly model of components in relative sliding contact with the bearing, the material information includes elastic modulus, Poisson's ratio, tensile strength and hardness, and the operating condition information includes the rotation speed of the rotor and the radial load on the sliding bearing.

[0024] Preferably, the step S2 includes the following sub-steps:

[0025] S21. Using the sliding bearing model as input, a sliding bearing assembly FEA model is established in ABAQUS finite element analysis software. The FEA model includes the bearing and components that have a relative sliding contact relationship with the bearing.

[0026] S22, setting of materials and contact parameters, using the collected sliding bearing material information as input, setting the elastic modulus and Poisson's ratio accordingly in the ABAQUS finite element analysis model, and using the penalty function friction formula to set the isotropic tangential behavior between the bearing contact surfaces;

[0027] S23, adaptive mesh region division, dividing the region of a certain depth on the inner hole surface of the bearing and selecting it as the ALE adaptive mesh region, so that the mesh cells therein are re-meshed in the wear simulation calculation;

[0028] S24. Use a coarse grid to mesh the outside of the bearing and a dense grid to mesh the adaptive grid area.

[0029] Preferably, the wear amount of the sliding bearing in the wear simulation calculation in step S23 reflects the mesh node displacement on the wear contact surface.

[0030] Preferably, the new coordinates of the grid node in step S33 depend on the location of the grid node and the locations of adjacent grid nodes in step S32.

[0031] Preferably, if the updated grid node i≥incremental step number M in step S3, step S4 is executed.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. The sliding bearing wear analysis method of the present invention is based on wear mechanism and adaptive grid algorithm. The bearing wear amount is obtained by fitting the friction and wear test data. It has good applicability to the wear characteristics of bearings of this type of materials. It is associated with the sliding bearing finite element model in the form of a subroutine to more accurately predict the wear morphology of the bearing wear contact surface.

[0034] 2. The present invention provides a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm. It predicts the wear of sliding bearings under various working conditions based on the simulation of sliding bearing digital prototypes, and proposes design improvement suggestions based on simulation data. In the sliding bearing verification stage, it supports the design of accelerated life test schemes for sliding bearings and calculates the acceleration factors under different test conditions.

[0035] 3. The sliding bearing wear analysis method of the present invention, which is based on wear mechanism and adaptive grid algorithm, verifies the underlying fault causes obtained by fault tree analysis and quantitatively analyzes sensitive factors. On the other hand, it performs simulation verification before conducting experimental verification of design improvements to achieve rapid iteration and optimized design. During the use stage, it supports field fault cause analysis of products such as pumps and compressors and simulation verification of design improvement measures. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of the sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm of the present invention;

[0037] Figure 2a and Figure 2b They are schematic diagrams of the structure of the rotor and the sliding bearing assembly in the aviation pump of the present invention;

[0038] Figure 3 It is a schematic diagram of the assembly model of the sliding bearing component in the present invention;

[0039] Figure 4 A schematic diagram of setting an adaptive grid area in the present invention;

[0040] Figure 5a and Figure 5b They are schematic diagrams of grid division of the sliding bearing assembly in the present invention;

[0041] Figure 6 is a load variation curve diagram of the sliding bearing in the present invention;

[0042] Figure 7 This is a diagram of the simulation results of sliding bearing wear in the present invention.

[0043] Reference numerals:

[0044] Main shaft 1, gear 2, sliding bearing 3. DETAILED DESCRIPTION

[0045] In order to fully describe the technical content, structural features, objectives and effects of the present invention, the following will be described in detail with reference to the accompanying drawings.

[0046] The sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm is used as a sliding bearing wear prediction method in the design process. Figure 1 As shown, it includes the following steps:

[0047] S1. Obtain information about sliding bearings, materials and operating conditions;

[0048] The structural information of the sliding bearing in step S1 includes the sliding bearing 3 and the assembly model of the components in relative sliding contact with the bearing, the material information includes the elastic modulus, Poisson's ratio, tensile strength and hardness, and the operating condition information includes the rotation speed of the rotor and the radial load on the sliding bearing.

[0049] S2, establishing a main finite element model of the sliding bearing, and using the ALE adaptive mesh algorithm to mesh the main finite element model of the sliding bearing;

[0050] Step S2 includes the following sub-steps:

[0051] S21. Using the sliding bearing model as input, a sliding bearing assembly FEA model is established in ABAQUS finite element analysis software. The FEA model includes the bearing and components that have a relative sliding contact relationship with the bearing.

[0052] S22, setting of materials and contact parameters, using the collected sliding bearing material information as input, setting the elastic modulus and Poisson's ratio accordingly in the ABAQUS finite element analysis model, and using the penalty function friction formula to set the isotropic tangential behavior between the bearing contact surfaces;

[0053] S23, adaptive mesh area division, dividing the area of ​​a certain depth on the inner hole surface of the bearing and selecting it as the ALE adaptive mesh area, so that the mesh units therein are re-meshed in the wear simulation calculation; in step S23, the wear amount of the sliding bearing in the wear simulation calculation reflects the displacement of the mesh nodes on the wear contact surface.

[0054] S24. A coarse grid is used to divide the mesh outside the bearing, and a dense grid is used to divide the mesh in the adaptive grid area. The inner ring of the bearing is in contact with each other. To prevent excessive invasion of the slave surface units into the main surface, the density of the slave surface mesh must be no less than that of the main surface mesh when dividing the mesh.

[0055] S3. Establish a sliding bearing wear sub-model, specifically including:

[0056] S31. Within the incremental step number M, the contact stress field of the bearing wear contact surface obtained by the main finite element model of the sliding bearing is used as input, and the wear amount of each grid node on the bearing wear contact surface is obtained by fitting the test data:

[0057] Δh=8.24×10-11 P 0.184 vΔt

[0058] Where P is the contact stress of the mesh node, v is the relative sliding velocity between the bearing and the spindle 1, and Δt is the current time increment;

[0059] S32, update the local coordinates n of the mesh nodes of the wear contact surface A , the grid update direction in the local coordinate system is the normal of the wear contact surface, and the local coordinate u3 of the normal direction of the grid node i is updated according to the adjacent grid node i-1 as follows:

[0060] u3 (i) ←u3 (i-1) -Δh

[0061] S33, after the grid node coordinates are updated, the global grid is scanned. After the grid scan is completed, each grid node is repositioned; the new coordinates of the grid node in step S33 depend on the position of the grid node in step S32 and the positions of the adjacent grid nodes.

[0062] S34. In the main finite element model of the sliding bearing, a mesh node B needs to be selected for the target mesh node A located at the edge of the wear contact surface, and the coordinates of the target mesh node A are updated by the global coordinates (x1, x2, x3) of the mesh node B, specifically:

[0063]

[0064] Δh=[Δh1,Δh2,Δh3] T

[0065] u (i) ←u (i-1) +M trans ·Δh

[0066] Among them, u (i) =[u1,u2,u3] T , M trans is the transformation matrix between the local coordinate system and the global coordinate system. The direction of the local coordinate system is related to the mesh topology. trans Obtained through finite element software.

[0067] If the updated grid node i ≥ the incremental step number M in step S3, step S4 is executed.

[0068] S4. Based on Fortran language programming, the sliding bearing wear sub-model is associated with the sliding bearing finite element main model in the form of a subroutine.

[0069] S5. Set the loading-wear-unloading analysis steps in the main finite element model of the sliding bearing, set the rotation speed and the working condition information of the radial load on the sliding bearing, complete the numerical calculation of the analysis steps according to the preset number of runs, and output the displacement field of each grid node of the wear contact surface of the sliding bearing.

[0070] S6. Based on the displacement field of each grid node of the wear contact surface of the sliding bearing, a wear distribution field diagram of the sliding bearing is generated to determine the concentrated wear area of ​​the sliding bearing.

[0071] The following is a further description of the sliding bearing wear analysis method based on the wear mechanism and the adaptive grid algorithm of the present invention in combination with the embodiments:

[0072] like Figure 2a and Figure 2b As shown, the sliding bearing in an aviation pump is used to support the rotation of the main shaft. The components in the aviation pump with relative sliding contact relationship mainly include the main shaft 1, the gear 2 and the sliding bearing 3, wherein the sliding bearing 3 includes a radial wear contact surface 4 in contact with the main shaft 1 and a wear contact surface 5 located on the end surface in contact with the gear 2. The wear of the sliding bearing causes the output performance of the aviation pump to deteriorate, and even seizure is a key failure mode of the product.

[0073] The wear distribution of a sliding bearing is predicted by using the sliding bearing friction damage analysis method of the present invention, which comprises the following steps:

[0074] S1. Obtaining information on the structure, material and operating conditions of the sliding bearing;

[0075] The structural information mainly includes the assembly model of the sliding bearing and the parts that have relative sliding contact with the bearing. The material information mainly includes the elastic modulus, Poisson's ratio, tensile strength, hardness and other information. The operating condition information mainly includes the rotation speed of the rotor and the radial load on the sliding bearing. The sliding bearing material and operating condition information parameters are:

[0076]

[0077]

[0078] S2. Establish the main finite element model of the sliding bearing. The specific steps are as follows:

[0079] S21. Using the sliding bearing CAD model as input, establish the sliding bearing assembly FEA model in ABAQUS finite element analysis software, such as Figure 3 As shown, it includes a sliding bearing 3, a gear 2 and a main shaft 1;

[0080] S22, setting of materials and contact parameters, the material property information given in step S1 is used as input, and the elastic modulus, Poisson's ratio and other corresponding settings are performed in the ABAQUS finite element analysis model. In terms of contact settings, isotropic tangential behavior is set between the contact surface of the bearing and the shaft, and the penalty function friction formula is used;

[0081] S23, adaptive grid area division, such as Figure 4 As shown in the figure, in order to improve the calculation accuracy of the mesh nodes in the wear area, the area of ​​a certain depth on the inner hole surface of the bearing is divided and selected as the ALE adaptive mesh area, so that the mesh units therein can be re-meshed in the wear simulation calculation. The wear amount during the simulation process is reflected in the displacement of the mesh nodes on this surface;

[0082] S24, grid division, such as Figure 5a and Figure 5b As shown in the figure, a coarser grid is used for the outer part of the bearing, and a denser grid is used for the adaptive grid area. Because the inner ring of the bearing is in contact with each other, in order to prevent the slave surface units from invading the master surface too much, the density of the slave surface grid must be no less than that of the master surface grid when dividing the grid.

[0083] S3. Establish a sliding bearing wear sub-model. The specific steps are as follows:

[0084] S31. Within the incremental step number, the contact stress field of the bearing wear contact surface obtained by the main finite element model of the sliding bearing is used as input to calculate the wear amount of each grid node on the wear contact surface, which is obtained by fitting the test data, specifically:

[0085] Δh=8.24×10 -11 P 0.184 vΔt

[0086] Where P is the contact stress of the mesh node, v is the relative sliding velocity, and Δt is the current time increment;

[0087] S32, update the local coordinates n of the mesh nodes of the wear contact surface A , the mesh update direction in the local coordinate system is the normal of the wear contact surface, and the local coordinate u3 of the mesh node normal direction is updated as:

[0088] u3 (i) ←u3 (i-1) -Δh

[0089] S33, after the grid node coordinates are updated, the global grid is scanned. After the grid scan is completed, each grid node will be repositioned;

[0090] S34. When the normal direction of the mesh node A located at the edge of the wear contact surface in the main finite element model of the sliding bearing cannot be directly defined, the mesh node B needs to be selected, and the coordinates of the target mesh node A are updated by the global coordinates (x1, x2, x3) of the mesh node B. The updated coordinates of the mesh node A are:

[0091]

[0092] Δh=[Δh1,Δh2,Δh3] T

[0093] u (i) ←u (i-1) +M trans ·Δh

[0094] Among them, u (i) =[u1,u2,u3] T , M trans is the transformation matrix between the local coordinate system and the global coordinate system. The direction of the local coordinate system is related to the mesh topology. trans Obtained through finite element software;

[0095] S4, based on Fortran language programming, the sliding bearing wear sub-model is associated with the sliding bearing finite element main model in the form of a subroutine;

[0096] S5. Set up the loading-wear-unloading analysis steps in the main finite element model of the sliding bearing, such as Figure 6 As shown, P1 loads the load → P2 loads and holds the load for a certain time → P3 unloads, sets the rotation speed and the radial load information of the sliding bearing, completes the numerical calculation of the analysis steps according to the preset number of runs, and outputs the displacement field of each grid node of the sliding bearing wear contact surface;

[0097] S6, displacement field of each mesh node based on the wear contact surface of the sliding bearing, such as Figure 7 As shown, a wear distribution field diagram is generated to determine the concentrated wear area of ​​the sliding bearing. The bearing wear depth is the largest at the contact center and gradually spreads to both sides. The wear depth on the side that fits the gear is relatively larger, which is consistent with the actual load state.

[0098] The present invention is a sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm. The sliding bearing surface wear calculation model is combined with the ALE adaptive grid algorithm. The relationship between material wear rate and contact force is obtained through experiments to fit the sliding bearing finite element main model. The ALE adaptive grid algorithm is used to simulate the contour changes caused by wear on the bearing surface and the impact on stress distribution in the sliding bearing model, and the coupled iterative solution of "current cycle wear calculation → wear contour change → stress distribution change → next cycle wear calculation" is realized to predict the wear conditions of the sliding bearing under various working conditions.

[0099] The embodiments described above are only descriptions of the preferred implementation modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm, characterized in that: It includes the following steps: S1. Obtain information on sliding bearings, materials and operating conditions; S2, establishing a main finite element model of the sliding bearing, and using the ALE adaptive mesh algorithm to mesh the main finite element model of the sliding bearing; S3. Establish a sliding bearing wear sub-model, specifically including: S31. Within the incremental step number M, the contact stress field of the bearing wear contact surface obtained by the main finite element model of the sliding bearing is used as input, and the wear amount of each grid node on the bearing wear contact surface is obtained by fitting the test data: Δh=8.24×10 -11 P 0.184 vΔt Where P is the contact stress of the mesh node, v is the relative sliding velocity between the bearing and the spindle, and Δt is the current time increment; S32, update the local coordinates n of the mesh nodes of the wear contact surface A , the grid update direction in the local coordinate system is the normal of the wear contact surface, and the local coordinate u3 of the normal direction of the grid node i is updated according to the adjacent grid node i-1 as follows: u3 (i) ←u3 (i-1) -Δh S33, after the grid node coordinates are updated, the global grid is scanned, and after the grid scan is completed, each grid node is repositioned; S34. In the main finite element model of the sliding bearing, a mesh node B needs to be selected for the target mesh node A located at the edge of the wear contact surface, and the coordinates of the target mesh node A are updated by the global coordinates (x1, x2, x3) of the mesh node B, specifically: Δh=[Δh1,Δh2,Δh3] T u (i) ←u (i-1) +M trans ·Δh Among them, u (i) =[u1,u2,u3] T , M trans is the transformation matrix between the local coordinate system and the global coordinate system. The direction of the local coordinate system is related to the mesh topology. trans Obtained through finite element software; S4, based on Fortran language programming, the sliding bearing wear sub-model is associated with the sliding bearing finite element main model in the form of a subroutine; S5. Setting a loading-wear-unloading analysis step in the finite element main model of the sliding bearing, setting the rotation speed and the working condition information of the radial load on the sliding bearing, completing the numerical calculation of the analysis step according to the preset number of runs, and outputting the displacement field of each mesh node of the wear contact surface of the sliding bearing; S6. Based on the displacement field of each grid node of the sliding bearing wear contact surface, a sliding bearing wear distribution field map is generated to determine the concentrated wear area of ​​the sliding bearing.

2. The sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm according to claim 1 is characterized in that: The structural information of the sliding bearing in step S1 includes the sliding bearing and the assembly model of the components in relative sliding contact with the bearing, the material information includes the elastic modulus, Poisson's ratio, tensile strength and hardness, and the operating condition information includes the rotation speed of the rotor and the radial load on the sliding bearing.

3. The sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm according to claim 1 is characterized in that: The step S2 comprises the following sub-steps: S21. Using the sliding bearing model as input, a sliding bearing assembly FEA model is established in ABAQUS finite element analysis software. The FEA model includes the bearing and components that have a relative sliding contact relationship with the bearing. S22, setting of materials and contact parameters, using the collected sliding bearing material information as input, setting the elastic modulus and Poisson's ratio accordingly in the ABAQUS finite element analysis model, and using the penalty function friction formula to set the isotropic tangential behavior between the bearing contact surfaces; S23, adaptive mesh region division, dividing the region of a certain depth on the inner hole surface of the bearing and selecting it as the ALE adaptive mesh region, so that the mesh cells therein are re-meshed in the wear simulation calculation; S24. Use a coarse grid to mesh the outside of the bearing and a dense grid to mesh the adaptive grid area.

4. The sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm according to claim 3 is characterized in that: The wear amount of the sliding bearing in the wear simulation calculation in step S23 reflects the mesh node displacement on the wear contact surface.

5. The sliding bearing wear analysis method based on wear mechanism and adaptive grid algorithm according to claim 1 is characterized in that: The new coordinates of the grid node in step S33 depend on the location of the grid node and the locations of the adjacent grid nodes in step S32.

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