| Along with the development of vehicles, besides pursuiting the speed and shape of vehicles, more and more people pay attention to the security performance of the vehicle. Fasteners are used to connect one or more parts of mechanical parts as a whole which is in a pivotal position of the vehicle system. In the process of high speed of the vehicle, once the critical fasteners appear rupture or collapse, it will lead to a series of institutions not working, the vehicle will appears unpredictable consequences. As a result, when design the vehicles shall ensure the performance of the fasteners.Today the fastener’s manufacturing and production process is relatively uniform,the investigations of the fasteners are confined to fasteners’ s performance and generic type selection. For the selection of fasteners domestic enterprises are still at the stage of by experience. The selection of the design of the fasteners usually inherit the fastener type of similar models at first or using the empirical formula in preliminary design, and then select fasteners by road test. In the enterprise experience formula there are many safety coefficients, it is difficult to guarantee the accuracy of the empirical formula, and in the process of calculation using the manual calculation is inefficient.This paper puts forward a kind of method based on the mathematical models when the vehicle is under dangerous conditions to solve the problem of suspension fastener type selection. And optimizes this kind of method in view of the present complex and low accuracy modeling to make it to be generalization and simplification.Concrete research content is as follows:First of all, use driving dynamics to analysis more than ten kinds of dangerous common situation of vehicles, and then sume up as three basic mathematical models,and analyse the acceleration limit value of each dangerous working conditions. At the same time use the the vehicle dynamics to calculate the tire forces and write the related four-wheel vehicles’ stress analysis software under more extreme condition.And then establish the front and rear suspension model accurately by ADAMS and do some relevant K&C tests, and then establish the accurate subsystem model and assemble them into the whole vehicle model. Through the test and simulation of the vehicle of ADAMS model proves the rationality of the mathematical model.Next extract the maximum of fasteners on the basis of the above work. Finally,use an instance of shock absorber to verify and analyse of the method, so that the fasteners meet the design requirements. Finally, based on two characteristic parameters of suspension——the suspension spring stiffness and shock absorber damping, optimize the fastening forces when the vehicle is under dangerous conditions by using the insight module in ADAMS. And complete the calculation of chassis bolt pre-tightening force and the design of tightening torque.The advantage of this design method is that once verify the accuracy of the stress analysis under limit working condition, it can directly use the mathematical model to solve the stress forces of the tire place. And the process of suspension modeling is simple, the simulation analysis is accurate. The simulation through the suspension model is simple and convenient, and it can realize the repeatability. |
