Modeling Of Leaf Spring And The Influence Of Its Stiffness On Ride Comfort

Leaf spring plays an important role in transferring force and torque between the frame and wheel, reducing the vibration from the road. Reasonable design parameters of the leaf spring can enhance the ride performance, safety and life of the vehicle. This thesis has a research on multi-leaf springs, the main contributions include:(1)Based on the leaf to leaf contact、leaf to clip contact and the sliding speed friction model, discrete beam modeling method is used to build multi-leaf springs according to its geometry parameters. This model is applied to calculate the leaf spring stiffness, and the result is verified by the test. S-shaped deformation、angle of its rotation and displacement are computed under braking condition.(2) The FEA method is used to build the leaf spring when the contact and friction phenomenon are taken into consideration. The leaf spring stiffness and strength are calculated under the full load or braking condition separately. The relationship between effective stiffness and the stroking amplitude, frequency and interleaf friction is presented in this paper. Effective spring rate decreases either the amplitude is increased or interleaf friction is reduced, the frequency has no influence on effective spring rate.(3) Vehicle ride simulation model is established in ADAMS/CAR according to the vehicle dynamical parameters. The accuracy of this model is verified through ride test. Using this ride model, the influence of different leaf spring rates on the ride performance is discussed. These analysis results can provide guidance on the suspension design.In this thesis, discrete beam method and FEA method are applied to build the leaf spring model separately. Its stiffness、strength and other characters are analyzed by the two methods. The model is also used to ride comfort simulation. These results can give instructions on the leaf spring design and manufacturing.