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The impact of local buckling on the behavior and strength of automotive components is discussed. Post-buckling strength must be included in the ultimate member strength calculations using the effective width concept. Member strength at the first onset of local buckling must be evaluated to avoid costly repairs. Local buckling changes the force deflection curve to be nonlinear after the first onset of local buckling. Methods for the calculations are discussed and presented. A computer program AISI/CARS, Computerized Applications and Reference System, is used to analyze a front rail to illustrate the benefit of considering local buckling in the design process.

Material constitutive modeling is an important aspect in the continuous improvement process for sheet metal forming simulation and analysis. In this study, a sensitivity study of material constitutive parameters on forming simulation results is carried out for two different sheet metal parts. Three different yield criteria are evaluated in the simulation including isotropic yield criterion, Hill's 1948 anisotropic yield criterion and Barlat's non-quadratic anisotropic yield criterion. It is found that the forming results depend upon the yield criterion used in the simulation. Both thinning and stress in the formed part are very sensitive to the change in anisotropy value (r-value). Effects of strain rate sensitivity of a material on forming results are demostrated through the use of two different stress and strain data from different tensile speeds. It is also found that forming results such as thinning are very sensitive to the strain hardening behavior of the material.