Dynamics Analysis And Life Prediction On Soft-top Convertible Roof Of Specific SUV

The folding soft-top roof, whose dynamics and wear make a direct impact on the stability and service life of vehicle, is one of the most important components of convertible. The soft-top convertible roof of specific SUV which is took as research object is simplified to be planar eight bar mechanism. It will be necessary to make dynamics analysis and life prediction of the soft-top convertible roof.The kinematic equations of the mechanism are established based on closed loop vector method. Newton-Raphson method is used to solve the equations with MATLAB. The D'Alember principle and Newton's Second Law are used to build mechanical balance equation of the dynamic inverse problem. The Lagrange method is used to build mechanical balance equation of the dynamic forward problem. The solution program of dynamic inverse problem is designed with MATLAB to get the binding curves of each joint hinge. 3D model of folding soft-top roof, which is built in Solidworks, is lead into ADAMS. The analog simulation is made to get results by using ADAMS. The results are compared with the numerical results to validate the kinematic and dynamic mathematical model of ideal mechanism. The nonlinear spring damping model modified coulomb model are used to build the hinge computing model of contact forces with clearance. Dynamic equations of the mechanism with clearance are established based on two-state clearance model. Through dynamics simulation with clearance using ADAMS, the effect of clearance on the dynamics performance is analyzed. Dimensional error, joint clearance and wear are took as random variable to establish kinematic error equation of the mechanism based on the loop increment method and effective length theory. The failure condition is discussed to build kinematics reliability equations. According to the given kinematics reliability, the life prediction of mechanism is completed.The result shows joint clearances have little effect on the motion curve of folding soft-top roof. Larger joint clearances result in both more severe fluctuation of constraint force and shorter reliable life. The presented analysis method has a great help on the structure analysis optimization of existing mechanisms and development of new mechanisms.