Vibration analysis of the spring in the shock absorber Schematic diagram In the shock absorber, the spring is deformed when subjected to liquid pressure, and a gap outflow occurs at the deformation, thereby acting as a damping effect. In fact, the reed is a thin circular plate. The mounting method in the shock absorber of the Xiali car is that the reed is supported on the outer periphery, and the inner hole is deformed under the force. In this way, the reed can be simplified to the illustrated structure. Calculation of the finite element method The calculation of the deformation of a single reed can be regarded as the bending problem of the thin plate. The elastic mechanics has already been theoretically solved. However, for a vibration damper in use, it is difficult for a single reed to achieve the specified damping force of the damper, so it is generally used in combination with different thickness reeds. In this paper, the thin plate element in the finite element method is used to calculate the overlapping deformation of the reeds. In the thin plate element, each node has only 3 degrees of freedom, namely the displacement ω in the Z direction, the rotation angle θX around the X axis, and the rotation angle θY around the Y axis.
Reducing the simplified model of the reed Because the thickness of the reed used in the shock absorber is small, and the external force acts only in the direction perpendicular to the plate surface, the deformation of the reed can be regarded as a bending problem of the thin plate. When the shock absorber is working, it can be considered that the pressure of the liquid acting on the surface of the valve plate is the same. Since the entire structure, load, and support are symmetrical, only 1/4 of the structure is calculated during calculation, as shown in b.
According to the structure of the shock absorber, the outer peripheral support of the reed can be regarded as a simple support for automotive technology. In calculation, it is considered that there is elastic contact between the reed and the reed. Determining the boundary conditions Based on the above model, it can be determined that the boundary conditions are: ω = 0 at the support; θX = 0 at the boundary along the X axis as the symmetry axis; θY = 0 at the boundary along the Y axis as the symmetry axis . Deformation Analysis of Reeds The Xiali sedan damper uses less than four reeds, so a maximum of four reed combinations are used in the calculation. When calculating, take the uniform pressure acting on the reed p=-110MPa, the outer diameter of the reed D=2210mm, the inner diameter d=1315mm, and the calculation results of the deformation of the valve plate in the radial direction are listed.
The calculation of the deformation of the combined reed cannot be replaced by one piece of reed (the thickness of which is the sum of the thicknesses of the pieces of the combined reed), and the deformation is calculated using the theoretical solution of elastic mechanics. When a n-piece spring with a thickness of δ is used in combination, the deformation amount is 1/n of the deformation amount of a sheet with a thickness of δ; when the n-piece thickness is δ, the deformation amount is smaller than a sheet with a thickness of nδ. Deflection of the reed. It can be seen that if the damper uses an equal-thickness reed, its deformation can be divided by one piece of deformation by the number of pieces, and the deformation of a single piece can be obtained from the theoretical solution of elastic mechanics.
When using unequal thickness reeds, the amount of deformation is independent of the arrangement of the reeds. Therefore, when assembling, as long as the thickness of each piece is correct, there is no need to care about different thickness sequences. The finite element method was used to calculate the deformation of the damper reed, and a qualitative test was performed on the rear shock absorber of the Xiali sedan. The extension valve of the damper used four reeds, the thickness of which was δ013, δ012 respectively. , δ0115 and δ012. Under the same conditions of other structures, only the installation sequence of the extension valve reeds was changed so that the thickness was arranged in order of δ012, δ0115, δ013, and δ012, and the experiment was again conducted. The dynamometers obtained from the two tests were identical, indicating that the mounting order of the reeds did not affect the deformation, and thus the resistance did not change. This shows that the calculation results are correct.
Conclusion The finite element method was used to calculate the reed deformation of the hydraulic shock absorber. The method was feasible and the calculation result was correct. The calculations show that when the thickness of each piece is different, the deformation of the combined reed is not equal to the deformation of a reed (the thickness of which is the sum of the combined thickness of the reeds), and then the theoretical solution of elastic mechanics is used. When each piece is the same thickness, the combination is used. The total deformation of the reed is evenly distributed to each reed, and the deformation of one reed can also be calculated by elastic mechanics. The total deformation is the deformation of one piece divided by the number of pieces. Calculations and tests have shown that the mounting sequence of the combined reeds has no effect on the deformation of the entire valve plate.
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