CAE calculation and analysis of the fracture of th

2022-08-07
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CAE calculation and analysis of the fracture of the differential housing of a light vehicle in order to find out the cause of the early failure and fracture of the differential housing of a light vehicle, we have made a comparative analysis of various assembly relationships, so as to provide a theoretical basis for judging the failure cause and structural improvement

1 CAD modeling and finite element model drive the pointer on the instrument panel to rotate and mark the tension value through mechanical transmission devices such as springs and weights

1.1 use 3D design software tools to draw the 3D digital model of the part, so as to facilitate further structural strength analysis, optimization and improvement. See the following figure for the model

1.2 read the CAD 3D digital analog into the ANSYS Workbench analysis environment through the special interface of ANSYS software

1.3 material properties and model boundary condition treatment

according to the actual motion state of the structure, the boundary condition is selected at the slotted shaft hole and the slotted shaft pin hole; The material of the part is QT, the elastic modulus is 1.73e5mpa, Poisson's ratio is 0.3, the density is 7.0e3kg/m3, the yield limit is 310mpa, and the tensile strength is 450MPa

1.4 load handling

apply torque to the model according to the design load

1.5 definition of working condition

considering the actual structure 4. fixation method of stroller handle: according to the assembly clearance of the structure required by different standards, there are three limit working conditions. First, the clearance between the pin shaft and the pin shaft hole is greater than that between the straight shaft and the straight shaft hole; Second, the clearance between the pin shaft and the pin shaft hole is equal to the clearance between the slotted shaft and the slotted shaft hole; Third, the clearance between the pin shaft and the pin shaft hole is less than that between the slotted shaft and the slotted shaft hole

1.6 element selection

considering that the fracture of the part may be caused by excessive local stress concentration, this analysis adopts solid elements and tries to control the lattice size and density. It is divided into 269456 nodes and 88192 elements. The CAE lattice model is shown in the following figure

2 calculation results

2.1 comparison of maximum stress values under three working conditions

2.2 three week working condition overall and local stress nephogram

2.2.1 the clearance between pin shaft and pin hole is greater than that between slotted shaft and slotted shaft hole:

overall and local stress distribution diagram

2.2.2 the clearance between pin shaft and pin hole is less than that between slotted shaft and slotted shaft hole:

2.2.3 the clearance between pin shaft and pin hole is equal to that between slotted shaft and slotted shaft.Shaft hole clearance:

3 I can be negative Conclusion

the linear elastic calculation method is adopted in this paper. At the same time, the strength of the differential housing is analyzed based on the premise that the pin shaft and the slotted shaft are not damaged. From the calculation and analysis results, there is a large problem of stress concentration in some parts, and the yield limit of materials is exceeded

cae analysis shows that:

1. Different assembly clearances have a great impact on the local stress, so different clearance fits should be paid attention to in the design process

2. In addition, the position and size of the maximum stress at the pin hole are related to the size of the pin shaft. This paper is calculated according to the length of the pin shaft and the pin hole

3. Large stress mainly occurs at the side with pin shaft. It is suggested that the position of pin shaft hole should be properly adjusted in the design improvement to make the wall thickness at the intersection of pin shaft and I-shaped shaft more uniform inside and outside. At the same time, can the overall thickness of the structure be increased here be considered

4. The maximum stress in the three cases occurs at the intersection of the pin hole and the slotted shaft hole, and at the place where the inner hole wall is relatively thin

5. Although the maximum stress value does not exceed the strength limit of 450MPa, the maximum value exceeds the yield limit of 310mpa. In this case, it is very easy to cause fatigue damage. The actual structure is also under alternating load at the maximum stress. If the above weak parts have material defects, it is easier to cause abnormal structure. 4 Adhesive: failure of tensile strength and elongation at break. (end)

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