A method for calculating fatigue life of an oil pump based on finite element software

Abstract

The present application belongs to the field of technical simulation, and relates to a fatigue life calculation method in the design process of an oil pump, in particular to a method for simulating and calculating the oil pump in the design process by using finite element software with fatigue life analysis, simulating according to actual tests or working conditions, and optimizing the structure of the oil pump according to the calculation results. The present application relates to a fatigue life calculation method of an oil pump based on finite element software. The fatigue life of a newly designed oil pump is simulated by using a numerical simulation method, and the weak points in the structural design are found out, thereby providing a basis for the optimization design of the structure and the improvement of product reliability. The natural frequency, vibration mode, response, damage and life of the oil pump are obtained, the weak points in the design of the oil pump are reflected more intuitively, and the oil pump is optimized and improved, thereby effectively avoiding damage caused by design defects of the oil pump in the test or working process.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of technical simulation, and relates to a fatigue life calculation method in the design process of an oil pump, in particular to a method for simulating and calculating an oil pump in the design process by using finite element software with fatigue life analysis, simulating according to actual tests or working conditions, and optimizing the structure of the oil pump according to the calculation results. The present application relates to a fatigue life calculation method for an oil pump based on finite element software. BACKGROUND

[0002] During the working process of an oil pump, fatigue cracks or damage may occur when subjected to various alternating loads. Simulation analysis is an important part of the design of an oil pump type, which can timely find weak links in the design at the early stage of product design, thereby providing data support for the optimization design of the structure, improving the product reliability, and shortening the product development cycle. Therefore, it is necessary to simulate the oil pump, evaluate the fatigue life of the oil pump, and propose a reasonable improvement scheme.

[0003] At present, the calculation method of the fatigue life of the oil pump in China mainly includes theoretical formula calculation, test and simulation. The traditional fatigue life calculation method mainly uses formula for theoretical calculation. This method generally solves the fatigue problem in the elastic range, does not consider local elastic-plastic deformation, has a large calculation error, and the method is relatively complicated. The fatigue life of the oil pump can also be obtained by using the general test method, but the test can only be carried out after the product design is completed, and the weak links of the structure cannot be predicted in advance. Moreover, the test is expensive and time-consuming. The fatigue life of the part is obtained by using the finite element simulation method, which has been applied in engineering. However, at present, there is still a lack of a complete fatigue life analysis process, and the steps such as simulation modeling, meshing and load application are not standardized and comprehensive. SUMMARY

[0004] OBJECTIVE

[0005] The problem to be solved by the present application is to provide a fatigue life calculation method for an oil pump based on finite element software with fatigue life analysis, to simulate the fatigue life of a newly designed oil pump by using a numerical simulation method, to find out the weak points in the structure design, and to provide a basis for the optimization design of the structure and the improvement of product reliability. In order to solve the technical problem,

[0006] TECHNICAL SCHEME

[0007] The technical scheme provided by the present application is as follows:

[0008] A fatigue life calculation method for an oil pump based on finite element software, comprising the following steps:

[0009] 1) Perform wear failure mechanism analysis on the oil pump to determine the simulation analysis object.

[0010] 2) Use three-dimensional modeling software to establish the entity model of the oil pump, and simplify the model by removing unnecessary parts and geometric characteristics that have no effect on the calculation results. The model has no interference and no free state. Unnecessary parts include bolts, nuts, gaskets, and springs. Geometric characteristics include threads, small fillets, small chamfers, and text.

[0011] 3) Import the finite element software with fatigue life analysis into the entity model in step 2), define the materials, contact pairs, mesh division, and boundary conditions of each part, and perform modal simulation calculation of the oil pump. The material parameters for oil pump modal calculation include density, elastic modulus, Poisson's ratio, S-N curve, yield limit, and fracture limit. Parts in contact with each other are set as bound contact. Define the boundary conditions of the oil pump, and the 0 displacement constraint of the oil pump mounting end face.

[0012] 4) According to the calculation results of step 3), use modal superposition method for harmonic response analysis, use finite element software with fatigue life analysis, associate harmonic response analysis system to modal analysis system, and perform harmonic response simulation calculation. Define the sweep range and damping parameters according to the actual situation. Use the aggregated model when using the modal superposition method to capture the behavior near the natural frequency. Define the load condition as the gravitational acceleration load, and the direction as the actual working or test vibration direction. If the load is in multiple vibration directions, such as along X, Y, and Z directions, it is necessary to re-establish the harmonic response analysis based on step 3), and the gravitational acceleration load direction should be consistent with the vibration direction.

[0013] 5) For steps 2) and 3), use finite element software with fatigue life analysis to perform vibration fatigue simulation calculation, associate the life vibration system to the modal analysis system, and then to the harmonic response analysis system.

[0014] 6) Solve and display the fatigue life calculation results.

[0015] Further, it further includes step 7), which calculates the final life of the oil pump and checks it.

[0016] Further, the step 1) considers all possible load types based on structural decomposition and load analysis, analyzes whether there is a wear-type failure mechanism for each part of the oil pump group during its life cycle, and determines the simulation analysis object of the oil pump.

[0017] Further, the step 3) of oil pump modal calculation needs to define the names of each part of the oil pump to ensure that the life calculation results of each part are obtained after fatigue life analysis.

[0018] Further, the step 3) oil pump modal calculation, checking the modal calculation result, when the calculation result is unreasonable, returning to the step 2) and the step 3), checking the calculation model, contact and boundary condition.

[0019] Further, the step 4) oil pump harmonic response calculation, the step 5) oil pump vibration fatigue life calculation, defining the load spectrum, including the random vibration load spectrum and the harmonic response load spectrum, the load spectrum being obtained from the test data or the actual working condition.

[0020] Further, the step 6) fatigue life calculation result includes the frequency and the mode shape of the oil pump and each component, the response curve, the damage and the life cloud atlas.

[0021] Further, the step 7) calculating the final life of the oil pump and checking, manually calculating the vibration fatigue life / hour of each part of the oil pump according to the simulated damage result, obtaining the final vibration fatigue life of the oil pump according to the shortest time principle and checking.

[0022] Further, if the load is in multiple vibration directions, the damage results of each part of the oil pump in each direction are superimposed to obtain the total damage of each part, and then the vibration fatigue life of each part of the oil pump is calculated and checked.

[0023] Further, the finite element software with fatigue life analysis is Workbench software.

[0024] The beneficial effects of the present application are:

[0025] The beneficial effects of the present application are: the oil pump fatigue life calculation using the above process, the establishment of a structure simulation model consistent with the actual design, the modal analysis, the harmonic response analysis and the fatigue life analysis, the natural frequency, the mode shape, the response, the damage and the life of the oil pump, and the comparison of the design weak points of the oil pump, and the optimization and improvement, thereby effectively avoiding the damage caused by the design defects of the oil pump in the test or working process.

[0026] The technical solution has been applied to a large number of oil pump design analyses, and has been fully verified through tests, and is technically feasible, the result is reliable, and effectively avoids the damage caused by the design defects of the oil pump in the test or working process. DETAILED DESCRIPTION

[0027] The present application will be further described below in conjunction with the embodiments. The following description is only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0028] The embodiment of the present application provides a lubricating oil pump fatigue life calculation method based on finite element software with fatigue life analysis, and according to the calculation result, necessary optimization and improvement are carried out on the lubricating oil pump structure, so as to improve the reliability of the lubricating oil pump. The method specifically comprises the following steps:

[0029] 1) Mechanism analysis.

[0030] The wear failure mechanism analysis is carried out on the lubricating oil pump, on the basis of structural decomposition and load analysis, all possible load types are considered, whether there is a wear failure mechanism in the service life of each part of the lubricating oil pump group is analyzed, and the simulation analysis object of the lubricating oil pump is determined;

[0031] 2) According to step 1), a three-dimensional modeling software is used to establish an assembly entity model of all simulation analysis objects of the lubricating oil pump, and the model is simplified, unnecessary parts and geometric characteristics without influence on the calculation result are removed, including threads, small fillets, small chamfers, text features, the model has no interference and free state;

[0032] 3) The entity model in step 2) is imported into the finite element software with fatigue life analysis, a modal analysis process is created, the materials, contact pairs, mesh division and boundary conditions of each part are defined, and the modal simulation calculation of the lubricating oil pump is carried out. If the calculation result is unreasonable, the calculation model, contact pairs and boundary conditions are checked, and the analysis is re-performed until the result is reasonable;

[0033] 4) According to the calculation result in step 3), the modal superposition method is used for harmonic response analysis, the harmonic response analysis system is associated to the modal analysis system by using the finite element software with fatigue life analysis, and the harmonic response simulation calculation is carried out. The sweep range and damping parameters are defined according to the actual situation. The load condition is defined as the gravity acceleration load, and the direction is the actual working or test vibration direction. If the load is in multiple vibration directions, such as along X, Y and Z directions, it is necessary to re-establish the harmonic response analysis based on step 3), and the gravity acceleration load direction is consistent with the vibration direction.

[0034] 5) The vibration fatigue simulation calculation is carried out on steps 2) and 3) by using the finite element software with fatigue life analysis; the load spectrum is defined, including random vibration load spectrum and harmonic response load spectrum, and the load spectrum is obtained from test data.

[0035] 6) The fatigue life calculation result is solved and displayed, including the frequency and mode shape, response curve, damage and life cloud of the lubricating oil pump as a whole and each part.

[0036] 7) Calculate the final life of the oil pump and check. According to the simulation damage results, the vibration fatigue life / hour of each part of the oil pump is calculated manually, and the final vibration fatigue life of the oil pump is obtained according to the principle of the shortest time and checked. The checking standard requires that the life / hour of the oil pump is greater than the vibration time required by the test. If the load is in multiple vibration directions, the damage results of each part of the oil pump in each direction are superimposed to obtain the total damage of each part, and then the vibration fatigue life of each part of the oil pump is calculated and checked.

[0037] Those skilled in the art can understand that, unless otherwise defined, all terms (including 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 belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the context of the prior art, and unless defined as such, should not be interpreted in an idealized or overly formal sense. The above specific embodiments further illustrate the purposes, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for calculating fatigue life of an oil pump based on finite element software, characterized in that, Comprising the following steps: Step 1) Perform wear failure mechanism analysis on the oil pump to determine the simulation analysis object; Step 2) Use three-dimensional modeling software to establish an oil pump solid model, and simplify the model by removing unnecessary parts and geometric characteristics that have no effect on the calculation results, and the model has no interference and no free state; unnecessary parts include bolts, nuts, gaskets, springs, and geometric characteristics include threads, small fillets, small chamfers, and characters, Step 3) Import the solid model in step 2) into the finite element software with fatigue life analysis, define the materials, contact pairs, mesh division, and boundary conditions of each part, and perform modal simulation calculation on the oil pump; The material parameters for oil pump modal calculation include: density, elastic modulus, Poisson's ratio, S-N curve, yield limit, and fracture limit; the parts in contact with each other are set as bound contact; define the boundary conditions of the oil pump, and the displacement constraint of the oil pump mounting end face 0; Step 4) According to the calculation results of step 3), perform harmonic response analysis using the modal superposition method, and use the finite element software with fatigue life analysis to associate the harmonic response analysis system to the modal analysis system for harmonic response simulation calculation; define the sweep range and damping parameters according to the actual situation; use the aggregated model when using the modal superposition method to capture the behavior near the natural frequency; define the load condition as the gravitational acceleration load, and the direction is the actual working or test vibration direction; if the load is in multiple vibration directions, such as along the X, Y, and Z directions, then the harmonic response analysis needs to be re-established based on step 3), and the gravitational acceleration load direction should be consistent with the vibration direction; Step 5) Use the finite element software with fatigue life analysis to perform vibration fatigue simulation calculation on steps 2) and 3), and associate the life vibration system to the modal analysis system and then to the harmonic response analysis system; Step 6) Solve and display the fatigue life calculation results.

2. The method of claim 1, wherein, It also includes step 7), which calculates the final life of the oil pump and checks it.

3. The method of claim 2, wherein, Step 1) Based on structural decomposition and load analysis, consider all possible load types, analyze whether there is a wear failure mechanism for each part of the oil pump during its life cycle, and determine the oil pump simulation analysis object.

4. The method of claim 3, wherein, Step 3) Oil pump modal calculation, define the name of each part of the oil pump to ensure that the life calculation results of each part are obtained after fatigue life analysis.

5. The method of claim 4, wherein, Step 3) Oil pump modal calculation, check the modal calculation results, and return to steps 2) and 3) to check the calculation model, contact, and boundary conditions when the calculation results are unreasonable.

6. The method of claim 5, wherein, Step 4) Oil pump harmonic response calculation, and step 5) oil pump vibration fatigue life calculation, define the load spectrum, including random vibration load spectrum and harmonic response load spectrum, which is obtained from test data or actual working conditions.

7. The method of claim 6, wherein, The fatigue life calculation results in step 6) include the frequency and mode shape, response curve, damage, and life cloud of the oil pump as a whole and each part.

8. The method of claim 7, wherein, The step 7) calculates the final service life of the oil pump and checks, according to the simulated damage result, the vibration fatigue life per hour of each part of the oil pump, according to the shortest time principle, the final vibration fatigue life of the oil pump is obtained and checked. The checking standard requires that the service life per hour of the oil pump is greater than the vibration time required by the test.

9. The method of claim 8, wherein, If the load is in multiple vibration directions, the damage results of each part of the oil pump along each direction are superimposed to obtain the total damage of each part, and then the vibration fatigue life of each part of the oil pump is calculated and checked.

10. The method of claim 9, wherein, The finite element software with fatigue life analysis is Workbench software.