The Experiment And Numerical Simulation In Surface Deflection Of Automobile Outer Panel

Surface deflection is the undulate region of the automobile outer panel and its height is between tens and thousands of microns. Now the most influenced element to improve the quality of the outer panels of sedan is the existence of surface deflection. With the use of thinner gauge sheets and the increasing application of higher strength steel sheet and aluminum sheet alloy in the auto-body, surface deflection have widely been taken into first consideration by engineers and researchers in the design and manufacture of auto-body panels.The geometrical models to study surface deflection is cylindrical shallow shell in this thesis, proceed the sheet metal forming experiment, measuring method of surface deflection is presented, the distribution of surface deflection on cylindrical shallow shell is obtained.The mathematical equations are formulated for two-dimensional surface deflection evaluation criterion and its geometrical essence and physical significance are illustrated. Based on the two-dimensional works, a three-dimensional evaluation criterion is given out and its validity is testified by experiments on cylindrical shallow shell and automobile front wing.Numerical model of the cylindrical shallow shell which is consistent with experiment is constructed. The forming and spring-back of shell part are investigated through numerical simulation. The results show: sheet metal can entirely flat punch over stamping, and surface deflection does not generate; surface deflection after spring-back exhibits M shape, and good agreement with amount by comparing numerical simulation with experimental results in cylinder direction. Through analyzing stress of the forming and spring-back of shell part, study the relationship between surface deflection and stress, the results show: stress is the requirement of engendering surface deflection.Take the cylinder shallow shell as the model, the influence rule of different...