Nowadays, as an irreplaceable means alongside CAD and testing, CAE is more and more widely applied with advanced material modeling and simulation methods continuously being explored, so as to get more accurate result as testing. In vehicle product development process, door slam durability evaluation is an important measurement for body closure structure. So far numerous effort has been taken to develop more mature methods to well define door slam simulation in stress and fatigue life analysis. Overall all methods ever being applied can be summarized as two categories, linear stress based method and nonlinear stress based method. The methodologies, such as inertia relief method, direct transient response solution, or local strain approach, can be included in linear stress based method with linear material properties as symbol in CAE model. In local strain approach, contact surface could be defined in the necessary area with consideration for more realistic load transfer. The complete process for linear stress based methodology is to retrieve the stress time history firstly from stress analysis and then take the data as input to further fatigue life analysis. In case plastic deformation will most likely appear, Neuber's rule is selected in parameter control to numerically convert high stress to nonlinear stress. While there are many cases that the structure may have large area local plastic deformation, nonlinear stress based method with nonlinear material property in CAE model will be a better option in stress prediction. The complete process for nonlinear stress based methodology is to retrieve the principal strain time history from nonlinear stress analysis and input those data directly to further fatigue analysis. In order to prove which method is more reasonable for door slam simulation, this investigation compares the linear and the nonlinear stress based methodology with LS-DYNA as solver in stress analysis and nCode DesignLife in fatigue life analyses. The conclusion is the linear stress based methodology is more conservative with higher stress and less fatigue life, while the nonlinear stress based methodology is more accurate in both stress and fatigue life for low cycle fatigue problem.
