Structural Characteristics Analysis And Optimization Of Driving Axle Of A Truck

The driving axle plays an irreplaceable role in the chassis of a truck.It not only bears the load imposed by the body and the road,but also needs to provide a good working condition for the transmission system.It is usually expected that the deflection of the driving axle housing under multiple extreme conditions should not be too large,ensuring sufficient stiffness and strength during working.This paper takes a truck driving axle as the research object,analyzes the mechanical characteristics of the driving axle under extreme conditions,and uses the methods of topology optimization and approximate models to carry out multi-objective optimization design on the reducer housing and the driving axle housing.The finite element models of the driving axle housing and reducer housing were established under the four extreme conditions of maximum vertical load,maximum driving load,emergency braking,and maximum lateral load,as well as transmission conditions.Comparing and analyzing the simulation results,it was found that the internal load generated by the transmission system under extreme conditions had a greater impact on the mechanical performance,such as deformation and stress,of the driving axle housing,up to 51%,and should not be ignored.In addition,the stress on the reducer housing was much smaller than the yield strength of the material,so it had a considerable potential for light-weighting.In the condition of maximum vertical load,the deformation of the driving axle housing needed to be reduced,and the structure needs to be improved to improve the structural stiffness.Considering that the main reducer housing belonged to a kind of casting and had enough space for lightweight design,the lightweight design of the main reducer housing was carried out by using topology optimization under the premise of ensuring that the meshing of the driving and driven gears was not affected.Firstly,the comprehensive evaluation function about static and dynamic characteristics was obtained through the evaluation function method,with the relative deformation of the bearing seat B-CD and the volume fraction of the reducer housing as constraints,and the original reducer housing was optimized by topology optimization results.The results showed that reducer housing achieved 11.7% reduction of weight with stiffness and frequency remained unchanged.Then,the result of the lightweight design was used as the base structure,the relative deformation of the bearing seat B-CD was used as the objective and the volume fraction as constraints,and the paving material under the premise of no motion interference was used as the design space for topology optimization.The topology optimization design reduce the relative deformation of bearing seat by 5.6% which is beneficial to the correct meshing of the driving and driven gears.Taking into account that the axle housing was made by stamping and welding,the shape on the surface cannot be modified at will.The inner diameter of the driving axle housing and the vertical height of the key section were selected as design variables,with minimizing the weight of the driving axle housing and the relative deformation of the bearing seat B-CD as objectives,the stiffness of driving axle housing as constraints,multi-objective parameter optimization design of the driving axle housing was performed through design of experiments,construction of approximate models with global response surface method.Subsequently,the final optimization plan was confirmed based on engineering practice.From the comparison of the results before and after optimization,it can be seen that when the mass of driving axle housing only increase by 2.3%,the relative displacement of B-CD can be decreased by 9.5%,and the stiffness of the driving axle housing can be increased by 10.5% at most,showing that the optimization effect is good.