CN115310222A - Strength analysis method for gearbox shell - Google Patents
Strength analysis method for gearbox shell Download PDFInfo
- Publication number
- CN115310222A CN115310222A CN202210849508.3A CN202210849508A CN115310222A CN 115310222 A CN115310222 A CN 115310222A CN 202210849508 A CN202210849508 A CN 202210849508A CN 115310222 A CN115310222 A CN 115310222A
- Authority
- CN
- China
- Prior art keywords
- finite element
- shell
- element model
- threaded hole
- stress
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/17—Mechanical parametric or variational design
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2111/00—Details relating to CAD techniques
- G06F2111/04—Constraint-based CAD
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/02—Reliability analysis or reliability optimisation; Failure analysis, e.g. worst case scenario performance, failure mode and effects analysis [FMEA]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Geometry (AREA)
- General Physics & Mathematics (AREA)
- Evolutionary Computation (AREA)
- General Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Computational Mathematics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
Abstract
An embodiment of the application provides a method for analyzing strength of a gearbox shell, which comprises the following steps: constructing a shell finite element model which comprises tooth bottom characteristics corresponding to all threaded holes on the gearbox shell; setting a thread frictional contact constraint of the shell finite element model; loading at least one load on the shell finite element model, and carrying out finite element simulation operation to obtain a stress cloud chart of the shell finite element model; and analyzing the static strength and the fatigue strength of the gearbox shell according to the stress cloud chart. According to the technical scheme, the strength of the threaded hole can be analyzed, the reliable durability of the threaded hole is detected, and therefore the strength analysis of the gearbox shell is completed.
Description
Technical Field
The application relates to the technical field of finite element simulation, in particular to a strength analysis method of a gearbox shell.
Background
In the field of simulation design of a gearbox, at present, no method for checking the strength of a threaded hole exists, and only strength checking is carried out on other areas of a shell. The threaded hole that suspension support was connected to the gearbox generally can adopt boss structure, and features such as boss structure's diameter can influence the rigidity of threaded hole. If the rigidity of the threaded hole is low, the thread is easy to deform due to external load under a high stress state, so that stress change is caused, and fatigue failure can be caused for a long time.
Based on this, there is a need for a strength analysis method for a transmission housing, which can analyze the strength of the threaded holes and detect the reliable durability of the threaded holes, thereby completing the strength analysis of the transmission housing.
Disclosure of Invention
The embodiment of the application provides a strength analysis method of a transmission shell, and then at least the strength of the threaded hole can be analyzed to a certain degree, the reliable durability of the threaded hole is detected, and therefore the strength analysis of the transmission shell is completed.
Other features and advantages of the present application will be apparent from the following detailed description, or may be learned by practice of the application.
According to an aspect of an embodiment of the present application, there is provided a method of analyzing strength of a transmission housing, the method including: constructing a shell finite element model which comprises tooth bottom characteristics corresponding to all threaded holes on the gearbox shell; setting a thread frictional contact constraint of the shell finite element model; loading at least one load on the shell finite element model, and carrying out finite element simulation operation to obtain a stress cloud chart of the shell finite element model; and analyzing the static strength and the fatigue strength of the gearbox shell according to the stress cloud chart.
In some embodiments of the present application, constructing a finite element model of a case that includes root features corresponding to respective threaded holes in the transmission case comprises: establishing at least one threaded hole local model according to the tooth bottom characteristics corresponding to each threaded hole on the gearbox shell, and converting each threaded hole local model into a hexahedron finite element model; meshing is conducted on other regions of the gearbox shell, and a tetrahedral finite element model is generated; and combining each hexahedral finite element model and the tetrahedral finite element model to construct a shell finite element model.
In some embodiments of the present application, based on the foregoing solution, the converting the local model of each threaded hole into a hexahedral finite element model includes: and (4) splitting the local model of each threaded hole along an axis plane, and performing grid division on each threaded hole section to generate a hexahedron finite element model corresponding to each threaded hole section.
In some embodiments of the present application, based on the foregoing solution, the meshing is performed on each threaded hole section, and a hexahedron finite element model corresponding to each threaded hole section is generated, including: and carrying out meshing on each threaded hole section, rotationally stretching the meshes of each threaded hole section into a hexahedron along the axis of the threaded hole, and generating a hexahedron finite element model corresponding to each threaded hole section.
In some embodiments of the present application, the setting of the threaded frictional contact constraint of the finite element model of the shell comprises: and setting the thread friction contact constraint of the shell finite element model by adopting a Langerhans multiplier method.
In some embodiments of the present application, said loading at least one load on said finite element model of the shell comprises: loading a thread pre-tightening load on the shell finite element model, wherein the thread pre-tightening load is used for representing the stress load between each bolt and the corresponding threaded hole; loading suspension working condition loads on the shell finite element model, wherein the suspension working condition loads are used for representing stress loads of bolts and threaded holes for suspension on the gearbox shell; and loading suspension vibration loads on the shell finite element model, wherein the suspension vibration loads are used for representing the vibration loads of the bolts and the threaded holes for suspension on the gearbox shell in at least one direction.
In some embodiments of the present application, the performing the static strength analysis of the gearbox housing according to the stress cloud map comprises: obtaining material mechanical property parameters of the transmission housing, the material mechanical property parameters being used to characterize mechanical properties of materials used to manufacture the transmission housing; and analyzing the static strength of the gearbox shell according to the stress cloud chart and the mechanical property parameters of the material.
In some embodiments of the present application, based on the foregoing solution, the performing static strength analysis of the gearbox housing according to the stress cloud chart and the mechanical property parameter of the material includes: comparing the stress magnitude at each position in the stress cloud chart with the mechanical property parameters of the material; and according to the comparison result of the stress at each position and the mechanical property parameters of the materials, completing the static strength analysis of the gearbox shell.
In some embodiments of the present application, said analyzing fatigue strength of the transmission housing from the stress cloud map comprises: acquiring material mechanical property parameters of the transmission shell, wherein the material mechanical property parameters are used for representing the mechanical properties of materials used for manufacturing the transmission shell; calculating the fatigue safety coefficient of the shell finite element model according to the material mechanical property parameters and the stress cloud chart; and analyzing the fatigue strength of the gearbox shell according to the fatigue safety coefficient.
In some embodiments of the present application, based on the foregoing scheme, said performing a fatigue strength analysis of the transmission housing according to the fatigue safety factor comprises: acquiring a standard fatigue safety factor, and comparing the fatigue safety factor with the standard safety factor; and according to the comparison result of the fatigue safety coefficient and the standard safety coefficient, completing the fatigue strength analysis of the gearbox shell.
Based on the scheme, the technical scheme provided by the application has at least the following advantages and progresses:
in this application, through the casing finite element model of the tooth bottom characteristic that the construction includes that each screw hole corresponds, carry out finite element simulation operation, obtain the stress cloud picture of casing finite element model, again according to the stress cloud picture is gone on the static strength analysis and the fatigue strength analysis of gearbox housing can effectively improve the modeling accuracy of casing finite element model, make it can laminate the actual conditions more, in addition, this application has still carried out the fatigue strength analysis except carrying out the static strength analysis, can analyze the intensity condition of gearbox housing in the use, can simulate the fatigue operating mode after the gearbox housing loads the whole car for the intensity analysis is more comprehensive.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application. It is obvious that the drawings in the following description are only some embodiments of the application, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. In the drawings:
FIG. 1 is a simplified flow chart diagram illustrating a method of analyzing the strength of a transmission housing according to one embodiment of the present application;
FIG. 2 illustrates a simplified flow chart of a method of analyzing the strength of a transmission housing according to one embodiment of the present application;
FIG. 3 shows a simplified representation of a geometric model of a thread;
FIG. 4 shows a conventional threaded hole geometric model diagram;
FIG. 5 illustrates a parallel threaded hole pattern diagram in accordance with an embodiment of the present application;
FIG. 6 illustrates a partial phantom schematic of a threaded hole in an embodiment in accordance with the present application;
FIG. 7 shows a schematic sketch of a grid of threaded holes according to an embodiment of the present application;
FIG. 8 illustrates a road load spectrum in one embodiment according to the present application;
FIG. 9 is a simplified flowchart illustration of a method of analyzing a strength of a transmission housing according to an embodiment of the present application;
FIG. 10 is a simplified flow chart diagram illustrating a method of analyzing the strength of a transmission housing according to one embodiment of the present application;
FIG. 11 illustrates a stress cloud in an embodiment in accordance with the present application;
FIG. 12 illustrates a comparative schematic of a finite element model of a casing being reinforced in accordance with an embodiment of the present application;
FIG. 13 illustrates a stress cloud after strengthening according to an embodiment of the present application;
FIG. 14 is a simplified flow chart diagram illustrating a method of analyzing the strength of the transmission housing according to one embodiment of the present application;
FIG. 15 is a simplified flowchart illustrating a method of analyzing the strength of the transmission housing according to one embodiment of the present application;
FIG. 16 shows S-N curves in an embodiment in accordance with the present application;
FIG. 17 illustrates a gearbox tap hole fatigue failure schematic according to an embodiment of the present application;
FIG. 18 illustrates a distributed cloud of threaded hole safety factors in an embodiment in accordance with the present application;
FIG. 19 illustrates a distributed cloud of threaded hole safety factors in an embodiment in accordance with the present application.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art.
Please refer to fig. 1.
FIG. 1 is a simplified flow diagram illustrating a method for strength analysis of a transmission housing according to an embodiment of the present application, which may include steps S101-S104, as shown in FIG. 1:
step S101, constructing a shell finite element model, wherein the shell finite element model comprises the tooth bottom characteristics corresponding to all threaded holes on the gearbox shell.
And S102, setting the thread friction contact constraint of the shell finite element model.
And S103, loading at least one load on the shell finite element model, and carrying out finite element simulation operation to obtain a stress cloud picture of the shell finite element model.
And step S104, analyzing the static strength and the fatigue strength of the gearbox shell according to the stress cloud chart.
In this application, can carry out finite element simulation operation through the casing finite element model of the tooth bottom characteristic that the constitution includes that each screw hole corresponds, obtain the stress cloud picture of casing finite element model again according to the stress cloud picture is gone on the static strength analysis and the fatigue strength analysis of transmission casing can effectively improve the accuracy of modelling of casing finite element model, make it can laminate actual conditions more, in addition, this application has still carried out the fatigue strength analysis except carrying out the static strength analysis, can analyze the intensity condition of transmission casing in the use, can simulate the fatigue operating mode of transmission casing loading after the whole car for the intensity analysis is more comprehensive.
Please refer to fig. 2.
FIG. 2 is a flow chart illustrating a method for analyzing strength of a transmission housing according to an embodiment of the present application, and as shown in FIG. 2, in step S101, the method for constructing a finite element model of the housing, the finite element model of the housing including root features corresponding to respective threaded holes of the transmission housing, may include steps S201-S203:
step S201, at least one threaded hole local model is built according to the tooth bottom characteristics corresponding to each threaded hole in the gearbox shell, and each threaded hole local model is converted into a hexahedral finite element model.
And step S202, carrying out meshing aiming at other regions of the transmission shell to generate a tetrahedral finite element model.
And S203, combining each hexahedral finite element model and the tetrahedral finite element model to construct a shell finite element model.
In this application, the bolt holes are replaced by cylindrical surfaces, as is common in the geometric figures of transmission housings. In order to check the reliability of the thread, a true geometric model of the thread must be constructed. The thread means a continuous convex portion of a specific section formed in a spiral shape on the surface of a cylindrical or conical parent body. For example, referring to fig. 3, fig. 3 shows a geometric model diagram of a thread, and as shown in fig. 3, the thread may include 5 elements: tooth form, nominal diameter, number of wires, pitch, and direction of rotation.
Wherein, the tooth shape: in a cross-sectional area passing through the axis of the thread, the profile shape of the thread is called a profile, and if the profile shape is divided according to the cross-sectional shape of the thread, the thread may be classified into a triangular thread, a trapezoidal thread, a rectangular thread, a zigzag thread, and other special-shaped threads.
Nominal diameter: the nominal diameter is a diameter representing the size of the thread and is divided into a major diameter, a minor diameter and a minor diameter.
Number of lines: a thread formed along one helix is called a single-start thread, and a thread formed along two or more helices equally spaced in the axial direction is called a multiple-start thread.
Pitch: the pitch refers to the axial distance between two corresponding points on the pitch diameter line of two adjacent teeth.
Rotating direction: refers to the screwing direction of the thread.
The real screw thread is in a spiral line shape, the grid is complex to construct, and the time consumption is long. In the existing thread grid construction method, only the characteristics of the thread form, the nominal diameter, the number of threads, the thread pitch and the like are reserved, and the bolt is tightly matched with the thread of the threaded hole, as shown in fig. 4, and a schematic diagram of a conventional threaded hole geometric model is shown in fig. 4. Under the influence of the nonlinear contact algorithm of the finite element analysis software, the node stress on the contact surface is not considered. The close contact between the threaded hole and the bolt therefore results in inaccurate stress information on the thread.
In step S201, in order to eliminate the influence, the crest and root features of the threads may be retained during the modeling process, and the helical threads are optimized to be parallel threads, so as to ensure the efficiency and accuracy of the thread stress calculation. For example, as shown in FIG. 5, FIG. 5 illustrates a parallel threaded hole pattern diagram in accordance with one embodiment of the present application.
In step S201, in the process of establishing at least one local threaded hole model, because the geometric features of the threads are far smaller than those of the other features of the shell, in order to ensure the calculation accuracy of the positions of the threads and the overall calculation efficiency, the threaded hole and the shell are cut, and a local sub-model is constructed by using the bolt. For example, as shown in FIG. 6, FIG. 6 illustrates a partial model diagram of a threaded hole in an embodiment according to the present application.
In step S201, the method for converting the partial model of each threaded hole into the hexahedral finite element model may include: and (4) splitting the local model of each threaded hole along an axis plane, and performing grid division on each threaded hole section to generate a hexahedron finite element model corresponding to each threaded hole section.
In this application, the method for generating the hexahedron finite element model corresponding to each threaded hole section by meshing each threaded hole section may include: and carrying out mesh division on each threaded hole section, rotationally stretching the mesh of each threaded hole section into a hexahedron along the axis of the threaded hole, and generating a hexahedron finite element model corresponding to each threaded hole section.
In this application, can carry out meshing with the screw hole cross-section that will cut out with each screw hole local model along the segmentation of axis plane. The thread section is divided into different regular areas by using a dividing line, and the threaded hole section is divided by using a quadrilateral mesh. The top and bottom meshes of the screw thread have more layers and small size so as to embody the geometrical characteristics of the screw thread. And the number of the grid layers is less when the grid layer is far away from the larger geometric surface of the screw teeth. The position nodes of the screwing of the bolts and the threaded holes are in one-to-one correspondence, and the calculation accuracy and the convergence efficiency are guaranteed. And rotating the grid on the cross section of the threaded hole for 360 degrees along the axis of the threaded hole to stretch out a hexahedron. The number of layers of the radial grids of the threaded holes can be 72 in the invention. For example, referring to fig. 7, fig. 7 shows a simplified schematic diagram of a grid of threaded holes in accordance with an embodiment of the present application.
In the present application, the method of setting a threaded frictional contact constraint of the finite element model of the shell may include: and setting the thread friction contact constraint of the shell finite element model by adopting a Langerian multiplier method.
In this application, the screw hole relies on the frictional force between the thread to reach the purpose of closing the screw up soon with the bolt, can optimize gearbox housing design through considering screw hole intensity problem, so, the precision of screw hole intensity calculation is very important. Compared with the whole gearbox shell, the structure characteristics of the screw threads are fine, contact finite element software is difficult to calculate convergence in a contact mode, and friction constraint is very important to set. In general, a friction constraint mode of parts adopts a Penalty function method (Penalty), the Penalty function method is suitable for most friction analysis, a tiny reversible sliding quantity gamma is introduced, convergence is improved, and the calculation accuracy is sacrificed due to a too large gamma value. The method adopts a Langrange Multiplier method (Lagrange Multiplier) and is suitable for the problem that the adhesion-sliding behavior needs to be accurately described.
In the application, a thread pretightening force load can be loaded on the shell finite element model, and the thread pretightening force load is used for representing the stress load between each bolt and the corresponding threaded hole.
In this application, bolt pretension is the main load of the bolt and the threaded hole. According to the grade of the bolt, the torque control precision, the friction coefficient and other factors, the maximum pretightening force and the minimum pretightening force of the bolt can be calculated. Aiming at the reliability problem, the maximum bolt pretightening force is used as the thread pretightening force load for loading.
In this application, can be in load suspension operating mode load on the casing finite element model, suspension operating mode load is used for the sign be used for the bolt of suspension and the atress load of screw hole on the gearbox casing.
In this application, what the bolt boss of gearbox suspension department mainly received is the load of suspension, and the suspension operating mode load in this application obtains through experimental way spectrum collection. After test errors such as burrs, mean shift and the like in the load spectrum signal are removed, an available road spectrum curve is obtained, and limit loads in 6 directions including positive and negative directions in the X direction, the Y direction and the Z direction under a finished vehicle coordinate system can be taken as suspension loads. For example, referring to fig. 8, fig. 8 illustrates a road load spectrum in accordance with an embodiment of the present application.
In the present application, the finite element model of the case may be loaded with suspension vibration loads that are used to characterize the vibration loads experienced by the bolts and threaded holes for suspension on the transmission case in at least one direction.
In this application, in order to check the fatigue durability of the threaded hole, it is also necessary to load the suspension vibration load. The edited road spectrum can be subjected to data statistical analysis, and the root mean square value is solved. The magnitude of the acceleration applied to the transmission suspension in each direction can be determined as the high cycle fatigue operating load as shown in table 1. And then building a dynamic model of the power assembly, calculating the load of the force applied to the suspension bracket, wherein the high cycle fatigue analysis working condition of the application is as shown in table 1:
TABLE 1 high cycle fatigue behavior
And on the basis of the assembly working condition, loading the high-cycle fatigue working condition to obtain a fatigue stress result under the fatigue working condition in each direction.
Please refer to fig. 9.
Fig. 9 is a simplified flowchart of a method for analyzing the strength of a transmission housing according to an embodiment of the present application, and as shown in fig. 9, in step S104, the method for analyzing the static strength of the transmission housing according to the stress cloud graph may include steps S901 to S902:
step S901, obtaining mechanical property parameters of a material of the transmission case, where the mechanical property parameters of the material are used for representing mechanical properties of a material used for manufacturing the transmission case.
And S902, analyzing the static strength of the gearbox shell according to the stress cloud chart and the mechanical property parameters of the material.
Please refer to fig. 10.
Fig. 10 is a simplified flowchart of a method for analyzing the strength of a transmission housing according to an embodiment of the present application, and as shown in fig. 10, in step S902, the method for analyzing the static strength of the transmission housing according to the stress cloud and the mechanical property parameter of the material may include steps S1001-S1002:
and S1001, comparing the stress magnitude of each position in the stress cloud picture with the mechanical performance parameters of the material.
And step S1002, completing static strength analysis of the gearbox shell according to the comparison result of the stress at each position and the mechanical performance parameters of the materials.
In the application, the failure of the metal material generally goes through four stages of elasticity, yield, strengthening and local deformation, and four characteristic points exist, and the corresponding stress is proportional limit, elastic limit, yield limit and strength limit in sequence. For the transmission case, the commonly used aluminum alloy material should be a brittle material as evaluated in terms of elongation after fracture. Generally, under the working condition of static strength limit, the reliability of the threaded hole can be ensured by meeting the condition that the maximum stress value of the threaded hole is smaller than the strength limit.
In the application, the maximum stress of each threaded hole can be determined through the stress cloud picture, or the position of the maximum stress of the shell finite element model is shown, whether the material failure easily occurs at the current position can be predicted by comparing the maximum stress with the strength limit in the mechanical property of the material, and then corresponding reinforcement optimization is carried out.
For example, referring to fig. 11, fig. 11 shows a stress cloud according to an embodiment of the present application, and as shown in fig. 11, the stress values of the thread roots of the threaded hole exceed the strength limit 240MPa of the shell material, and the analysis result of the stress cloud shows that the threaded hole has a failure risk. After the actual manufacturing of the gearbox shell is carried out, cracks appear at corresponding positions, and the accuracy of the technical method is further verified.
Therefore, the failure of the position of the threaded hole can be judged mainly because the rigidity of the bolt boss is insufficient, and the threaded hole deforms under the suspension limit load, so that the stress at the bottom of the threaded hole is out of tolerance. The reliability optimization mode of the threaded hole is mainly to improve the deformation resistance of the threaded hole at the position with poor rigidity.
In the present application, the following method may be adopted for reinforcement optimization:
1. increasing the wall thickness of the boss of the threaded hole;
2. reinforcing ribs are added on the outer sides of the failure positions of the threaded holes;
3. and thickening the original reinforcing ribs.
For example, referring to FIG. 12, FIG. 12 illustrates a comparative schematic of a finite element model of a shell being reinforced according to an embodiment of the present application. Referring to fig. 13, fig. 13 shows a stress cloud after strengthening according to an embodiment of the present application, as shown in fig. 13, root stresses at the failure positions of the strengthened threaded holes are all below the strength limit, and later production verification also proves that the same positions do not appear.
Please refer to fig. 14.
Fig. 14 shows a flow chart of a method for analyzing the strength of the transmission housing according to an embodiment of the present application, and as shown in fig. 14, in step S104, the method for analyzing the fatigue strength of the transmission housing according to the stress cloud graph may include steps S1401-S1403:
step 1401, obtaining mechanical property parameters of a material of the gearbox housing, wherein the mechanical property parameters of the material are used for representing mechanical properties of a material used for manufacturing the gearbox housing.
And S1402, calculating the fatigue safety coefficient of the shell finite element model according to the material mechanical property parameters and the stress cloud chart.
And S1403, analyzing the fatigue strength of the gearbox shell according to the fatigue safety coefficient.
Please refer to fig. 15.
Fig. 15 shows a flow chart of a method for analyzing the strength of the transmission housing according to an embodiment of the present application, and as shown in fig. 15, in step S1403, the method for analyzing the fatigue strength of the transmission housing according to the fatigue safety factor may include steps S1501-S1502:
step S1501, obtaining a standard fatigue safety factor, and comparing the fatigue safety factor with the standard safety factor.
And S1502, according to the comparison result of the fatigue safety coefficient and the standard safety coefficient, completing fatigue strength analysis of the gearbox shell.
In the application, the mechanical performance parameters of the material and the stress cloud picture are used for calculating the fatigue safety factor of the shell finite element model, and then the fatigue safety factor and the standard safety factor can be used for predicting whether the material fatigue failure easily occurs at the current position or not, and then corresponding reinforcement optimization is carried out.
In the present application, calculating the fatigue safety factor requires material mechanical property parameters of the shell material, and the specific material mechanical properties can be shown in table 2.
TABLE 2 mechanical Property parameters of the Shell Material
The mechanical performance parameters of the material are imported into fatigue software, and an S-N curve of the material can be obtained, wherein the S-N curve is an important basis for calculating the fatigue safety coefficient. The basic S-N curve of the material shows the crack initiation life of the smooth material under the action of constant amplitude symmetrical cyclic stress. For example, referring to FIG. 16, FIG. 16 shows an S-N curve in accordance with one embodiment of the present application.
In the present application, there are many factors that influence the S-N curve. The standard S-N curve is derived from a test specimen test, but the distinction between the specimen and the actual part needs to be taken into account in the calculation.
(1) Stress gradient
The smooth sample is free from stress concentration, but the actual part may have grooves or notches, and stress concentration and notch correction are required.
(2) Dispersion of
Even with the same test material, the experimental results have some discrepancies. The dispersion is defined as the ratio of the fatigue strength at 10% survival to the fatigue strength at 90% survival.
(3) Mean stress
In practice, the stress time history of the parts is usually asymmetric, that is to say the cycle characteristics are different. Therefore, the average stress correction of the stress time history is required. The purpose of the correction is to convert the actual stress state of the part to a state of stress ratio at the time of material testing according to the equal lifetime.
(4) Size effect
For tension and compression loading, the larger the diameter and the larger the circumference, the greater the probability of weakness and the more and earlier cracks appear. The fatigue resistance of the large-sized member is lower than that of the small-sized sample.
(5) Surface finishing
Fatigue cracks usually initiate at the surface of the part, so the surface condition has a large effect on fatigue life. The higher the surface finish, the longer the time to fatigue crack formation. Typically, residual stress in the surface layer will affect crack initiation and residual compressive stress may retard the development of high cycle fatigue cracks. The pre-compression of the surface layer can be obtained by the processes of shot blasting, cold rolling, nitriding and the like, the gearbox shell is a cast part, and a compact layer is usually arranged on the surface of the gearbox shell, so that the safety coefficient can be improved.
The machining process of the threaded hole has the difference between cutting threads and extruding threads, and different machining processes have large influence on parameter setting of fatigue calculation of the threaded hole.
Therefore, according to the influence factors, the fatigue calculation accuracy of the threaded hole can be guaranteed by setting parameters. For example, a list of material mechanical property parameters for a cast aluminum alloy can be shown in table 3.
TABLE 3 mechanical Property parameters of the Shell Material
| Influencing factor | Numerical value |
| Stress gradient | ON |
| Mean stress | ON |
| Mean stress adjustment | OFF |
| Modified chart of hessian | OFF |
| Statistical influence | ON |
| Survival rate | 99.99％ |
| Dispersion of | 1.4 |
| Surface roughness | 60μm |
| Process size effect | 15mm |
| Coefficient of surface strength | 1.5 |
For example, referring to FIG. 17, FIG. 17 illustrates a gearbox (reduction gearbox) tapped hole fatigue failure diagram according to one embodiment of the present application. The current machining process for a failed threaded hole is cutting machining, and for the threaded hole, the fatigue parameter settings are shown in table 4.
TABLE 4 mechanical Property parameters of the screw hole cutting Process
With reference to fig. 18, fig. 18 shows a cloud of distribution of the fatigue safety factors for threaded holes in an embodiment according to the present application. Standard fatigue safety factor in this application can be decided to be 1.1, standard fatigue safety factor can be through several gearboxes of statistics factor of safety under the same test, takes the minimum factor of safety as the evaluation standard. The fatigue analysis result shows that the fatigue safety coefficient of the threaded hole is 0.764, the threaded hole is positioned at the first tooth bottom position, the threaded hole is consistent with the test failure position, and the fatigue safety requirement is not met.
Due to the boundary limitation of the digifax, the threaded hole is optimized on the basis of not modifying the digifax. In this application, can change the cutting process mode of screw hole into extrusion technology. Taking these factors into account, the fatigue parameters of the threaded hole produced by the extrusion process can be set as shown in table 5.
TABLE 5 threaded hole cutting Process mechanical Property parameters
| Influence factor | Thread-cut |
| Stress gradient | ON |
| Mean stress | OFF |
| Mean stress adjustment | OFF |
| Modified hessian chart | ON |
| Survival rate | 99.99％ |
| Dispersion of | 1.26 |
| Surface roughness | OFF |
| Process size effect | OFF |
| Coefficient of surface strength | 2.2 |
Referring next to fig. 19, fig. 19 shows a cloud of distributions of the safety factors of the threaded holes according to an embodiment of the present application, as shown in fig. 19, after process optimization, the minimum fatigue safety factor of the threaded holes reaches 1.324, and the threaded holes are located at the first root position. After optimization, the scheme is verified by tests, and the feasibility of process optimization is shown.
In conclusion, in this application, through the casing finite element model that founds the tooth bottom characteristic that includes each screw hole correspondence, carry out finite element simulation operation, obtain the stress cloud chart of casing finite element model, again according to the stress cloud chart carries out the static strength analysis and the fatigue strength analysis of gearbox casing can effectively improve the modeling accuracy of casing finite element model, make it can laminate actual conditions more, in addition, this application is except carrying out static strength analysis, has still carried out fatigue strength analysis, can analyze the strength condition of gearbox casing in the use, can simulate the fatigue operating mode after the gearbox casing loads the whole car for strength analysis is more comprehensive.
Other embodiments of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the application and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains.
It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.
Claims (10)
1. A method of strength analysis of a transmission housing, the method comprising:
constructing a shell finite element model which comprises the tooth bottom characteristics corresponding to all the threaded holes on the gearbox shell;
setting a threaded frictional contact constraint of the shell finite element model;
loading at least one load on the shell finite element model, and carrying out finite element simulation operation to obtain a stress cloud chart of the shell finite element model;
and analyzing the static strength and the fatigue strength of the gearbox shell according to the stress cloud chart.
2. The method of claim 1, wherein constructing a finite element model of the case that includes root features for each threaded hole in the transmission case comprises:
establishing at least one threaded hole local model according to the tooth bottom characteristics corresponding to each threaded hole on the gearbox shell, and converting each threaded hole local model into a hexahedron finite element model;
meshing is carried out on other regions of the gearbox shell to generate a tetrahedral finite element model;
and combining each hexahedral finite element model and the tetrahedral finite element model to construct a shell finite element model.
3. The method of claim 2, wherein converting each partial threaded hole model into a hexahedral finite element model comprises:
and (4) dividing the local model of each threaded hole along an axis plane, and performing meshing aiming at each threaded hole section to generate a hexahedron finite element model corresponding to each threaded hole section.
4. The method according to claim 3, wherein the gridding is performed on each threaded hole section to generate a hexahedral finite element model corresponding to each threaded hole section, and the method comprises the following steps:
and carrying out meshing on each threaded hole section, rotationally stretching the meshes of each threaded hole section into a hexahedron along the axis of the threaded hole, and generating a hexahedron finite element model corresponding to each threaded hole section.
5. The method of claim 1, wherein the setting a threaded frictional contact constraint of the finite element model of the shell comprises:
and setting the thread friction contact constraint of the shell finite element model by adopting a Langerhans multiplier method.
6. The method of claim 1, wherein said loading at least one load on said finite element model of the shell comprises:
loading a thread pre-tightening load on the shell finite element model, wherein the thread pre-tightening load is used for representing the stress load between each bolt and the corresponding threaded hole;
loading suspension working condition loads on the shell finite element model, wherein the suspension working condition loads are used for representing stress loads of bolts and threaded holes for suspension on the gearbox shell;
and loading suspension vibration loads on the shell finite element model, wherein the suspension vibration loads are used for representing the vibration loads on the bolts and the threaded holes for suspension on the gearbox shell in at least one direction.
7. The method of claim 1, wherein the performing a static strength analysis of the gearbox housing from the stress cloud map comprises:
acquiring material mechanical property parameters of the transmission shell, wherein the material mechanical property parameters are used for representing the mechanical properties of materials used for manufacturing the transmission shell;
and analyzing the static strength of the gearbox shell according to the stress cloud chart and the mechanical property parameters of the material.
8. The method of claim 7, wherein the performing a static strength analysis of the gearbox housing from the stress cloud and the material mechanical property parameter comprises:
comparing the stress magnitude at each position in the stress cloud chart with the mechanical property parameters of the material;
and according to the comparison result of the stress at each position and the mechanical property parameters of the materials, completing the static strength analysis of the gearbox shell.
9. The method of claim 1, wherein said analyzing fatigue strength of said transmission housing from said stress cloud map comprises:
obtaining material mechanical property parameters of the transmission housing, the material mechanical property parameters being used to characterize mechanical properties of materials used to manufacture the transmission housing;
calculating the fatigue safety coefficient of the shell finite element model according to the material mechanical property parameters and the stress cloud chart;
and analyzing the fatigue strength of the gearbox shell according to the fatigue safety factor.
10. The method of claim 9, wherein said performing a fatigue strength analysis of said transmission housing based on said fatigue safety factor comprises:
acquiring a standard fatigue safety factor, and comparing the fatigue safety factor with the standard safety factor;
and according to the comparison result of the fatigue safety factor and the standard safety factor, completing the fatigue strength analysis of the gearbox shell.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210849508.3A CN115310222A (en) | 2022-07-19 | 2022-07-19 | Strength analysis method for gearbox shell |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210849508.3A CN115310222A (en) | 2022-07-19 | 2022-07-19 | Strength analysis method for gearbox shell |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN115310222A true CN115310222A (en) | 2022-11-08 |
Family
ID=83856595
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210849508.3A Pending CN115310222A (en) | 2022-07-19 | 2022-07-19 | Strength analysis method for gearbox shell |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN115310222A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116502329A (en) * | 2023-04-11 | 2023-07-28 | 蜂巢传动科技邳州有限公司 | Transmission case strength analysis method, transmission case strength analysis device, electronic device, and storage medium |
| CN116992741A (en) * | 2023-09-26 | 2023-11-03 | 盛瑞传动股份有限公司 | Method, device, medium and equipment for checking strength of gearbox shell |
-
2022
- 2022-07-19 CN CN202210849508.3A patent/CN115310222A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116502329A (en) * | 2023-04-11 | 2023-07-28 | 蜂巢传动科技邳州有限公司 | Transmission case strength analysis method, transmission case strength analysis device, electronic device, and storage medium |
| CN116502329B (en) * | 2023-04-11 | 2024-01-05 | 蜂巢传动科技邳州有限公司 | Transmission case strength analysis method, transmission case strength analysis device, electronic device, and storage medium |
| CN116992741A (en) * | 2023-09-26 | 2023-11-03 | 盛瑞传动股份有限公司 | Method, device, medium and equipment for checking strength of gearbox shell |
| CN116992741B (en) * | 2023-09-26 | 2024-01-02 | 盛瑞传动股份有限公司 | Method, device, medium and equipment for checking strength of gearbox shell |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN115310222A (en) | Strength analysis method for gearbox shell | |
| CN109635385B (en) | Part service life prediction method comprehensively considering fatigue strength influence factors | |
| CN110059449B (en) | Crankshaft fatigue limit load prediction method based on improved stress field intensity method | |
| Rahman et al. | Fatigue life prediction of lower suspension arm using strain-life approach | |
| CN111651924A (en) | Weight function-based surface crack stress intensity factor database establishment method | |
| CN111914358B (en) | Method for forecasting limit bearing capacity of transmission shell under impact action of engine | |
| Muhammad et al. | Design optimization of a diesel connecting rod | |
| CN112668217B (en) | Analysis method and device for main bearing hydrodynamic lubrication based on designed profile | |
| Reza Kashyzadeh et al. | Experimental and finite element studies on free vibration of automotive steering knuckle | |
| Sanders et al. | An experimental investigation of the effect of tooth asymmetry and tooth root shape on root stresses and single tooth bending fatigue life of gear teeth | |
| Song et al. | Ultimate behaviour and rotation capacity of stainless steel end-plate connections | |
| Aziz et al. | Probabilistic simulation approach to evaluate the Tooth-Root strength of Spur gears with FEM-Based verification | |
| CN112199779B (en) | Design method of equal-thickness-shrinkage-ratio fatigue test model | |
| CN115563824A (en) | Method for predicting performance of dual-phase material composite tube based on machine learning | |
| CN114139271A (en) | Method and device for determining reliability of gearbox shell | |
| Slima et al. | Fatigue analysis-based numerical design of stamping tools made of cast iron | |
| CN112834370A (en) | Method for establishing reliability-assured degradation equation of aerospace mechanism product | |
| Wang et al. | Cost benefit analysis of condition monitoring systems for optimal maintenance decision making | |
| CN112749444B (en) | Method for establishing reliability margin model for space mechanism product assurance | |
| Hu et al. | Study of the influences of transient crack propagation in a pinion on time-varying mesh stiffness | |
| Sanders | An experimental investigation of the influence of elliptical root shapes and asymmetric teeth on root stresses and bending fatigue lives | |
| CN116805102B (en) | Shape optimization design method for inner surface of elliptical head of composite container | |
| Jia et al. | Design research on the unmeshed thread section structure of engine conrod bolts | |
| CN114880800B (en) | Comprehensive gear shaping method for improving tooth surface unbalanced load | |
| CN109522678B (en) | Precise pre-tightening design method for forging die |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |