<jats:p>The mechanical properties of joined structures are determined considerably by the chosen joining technology. With the aim of providing a method that enables a faster and more profound decision-making in the spatial distribution of joining points during product development, a new method for the load path analysis of joining points is presented. For an exemplary car body, the load type in the joining elements, i.e. pure tensile, shear and combined tensile-shear loads, is determined using finite element analysis (FEA). Based on the evaluated loads, the resulting load paths in selected joining points are analyzed using a 2D FE-model of a clinching point. State of the art methods for load path analysis are dependent on the selected coordinate system or the existing stress state. Thus, a general statement about the load transmission path is not possible at this time. Here, a novel method for the analysis of load paths is used, which is independent of the alignment of the analyzed geometry. The basic assumption of the new load path analysis method was confirmed by using a simple specimen with a square hole in different orientations. The results presented here show a possibility to display the load transmission path invariantly. In further steps, the method will be extended for 3D analysis and the investigation of more complex assemblies. The primary goal of this methodical approach is an even load distribution over the joining elements and the component. This will provide a basis for future design approaches aimed at reducing the number of joining elements in joined structures.</jats:p>

Microstructure transformation due to thermo-mechanical processing have an acute effect the macroscopic properties of low carbon steels. This effect includes visco-plastic deformation and phase transformations. Hot forming processes such as press hardening are particularly affected. Most engineering applications require a combination of high strength and sufficient residual ductility, which can be achieved by the development of graded microstructures. In the present work, the evolution of phase transformations is investigated by linking experiments and simulations to produce graded microstructures. For this purpose, an extended material model is proposed to represent the evolution of phase transformations under inhomogeneous heating and cooling strategies. On the experimental side, phase transformations are identified during thermo-mechanical treatment of flat steel specimens using digital image correlation and thermal imaging. Based on the experimental results, the material parameters are identified, and the simulation model is validated. On the numerical side an algorithm for the finite-element simulation of phase transformations in low carbon steels is proposed. The evolution of phase transformations is presented for the simulation of tensile specimen employing the finite-element-method.