The Fatigue Life Analysis Of A Commercial Vehicle Cab Based On Virtual Iteration

With the improvement of economic level,China's automobile industry gets rapid development,the durable reliability of the vehicle gets more and more attention from the enterprise,its performance is good or not directly affects the car market competitiveness.In this paper,taking the cab of a commercial vehicle as the research object,based on the principle of virtual iteration calculating the load spectrum of cab and frame joint,the fatigue simulation analysis of the cab is carried out by using the finite element and fatigue analysis theory.Finally,the fatigue simulation results is verified through the bench test,the cab structure optimization is carried out based on the fatigue simulation results,and its fatigue crack problem is resolved.In this paper,based on the CATIA three-dimensional model of the cab,the finite element model of the whole interior cab is established in Hypermesh software,and the inertial release static analysis under the unit load is carried out.The difficulty of establishing the finite element model is how to add welding spot and accessories of all cab interior,the Acm solid unit is used to simulate the spot welding,and the seam welding is simulated through the shell element,and the interior is added in the form of concentrated mass,so that it not only satisfies the its mechanical properties but also makes model more simple.The extraction of the load spectrum is also an important part of the fatigue analysis of the cab in this paper,the load spectrum of cab is extracted by virtual iterative method,this method is based on multi-body dynamics model of the cab and frame,which is build Adams,the mechanical parameters of the various parts of the model,such as the centroid and moment of inertia of the cab and the stiffness characteristics of damping,is obtained through experimenting.Based on the multi-body model and the accelerating signal of the cab,the excitation signal of the cab and frame model is obtained in the virtual iteration Femfat.lab software,finally,the load spectrum of the cab suspension is obtained through the multi-body dynamics simulation analysis.Taking the static analysis result of the inertia of the cab under the unit load as the carrier,fatigue simulation analysis is taken by the load spectrum of cab suspension and the material E-N curve in nCode fatigue software.In order to get more accurate fatigue analysis results of the cab,the bench fatigue test is carried,to verify the result is accurate.Finally,based on the results of fatigue analysis and experimental verification,the structural optimization of the cab is taken,and the cab cracking problem is solved.This article adopts the method of experiment combined with virtual simulation,which greatly shortens the cycle of fatigue analysis and ensure its accuracy.