Axial crash of thin-walled circular aluminum tubes is investigated in this study. These kinds of tubes usually are used in automobile and train structures to absorb the impact energy. An explicit finite element method (FEM) is used to model and analyse the behaviour. Formulation of the energy absorption and the mean crash force in the range of variables is presented using design of experiments (DOE) and response surface method (RSM). Comparison with experimental tests has been accomplished in some results for validation. Also, comparison with the analytical aspect of this problem has been done. Mean crash force has been considered as a constraint as its value is directly related to the crash severity and occupant injury. The results show that the triggering causes a decrease in the maximum force level during crash.

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The kinetics of multiphase transformation is more complicated than single phase transformation due to the effects of prior phase transformation on the subsequent transformations. The authors have previously proposed a new method to estimate the parameters related to the isothermal kinetics of single phase transformation. This current paper investigates the application of the authors’ method to the bainite transformation process of multiphase steel G18CrMo2-6. The mathematical relationship between Pro-eutectoid ferrite (Pro-EF) fractions and the kinetics related parameters of the subsequent bainite transformation during heat treatment processes in the G18CrMo2-6 multiphase steel has been investigated. The results show the significant effect of Pro-EF fractions on the start and finish temperatures and the isothermal phase transformation parameters ‘ b’ of subsequent bainite transformation.

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