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Modelling and simulation of the joining zone during the tailored forming process

Modelling and simulation of the joining zone during the tailored forming process

Leaders:  F. Aldakheel, P. Wriggers
Team:  C. Böhm, F. Töller
Year:  2019
Sponsors:  DFG im Rahmen des SFB 1153

[Translate to Englisch:]

The overall objective of the collaborative research center "Tailored Forming" (CRC 1153) is to open up the potential for hybrid solid components on the basis of a new tailored manufacturing process using joined semi-finished products. In contrast to existing manufacturing and production processes of hybrid components, in which the joining process takes place during forming or at the end of the production chain, the tailored semi-finished products used in the CRC 1153 are joined before the forming process. Compared to the existing manufacturing process, the simple geometry of semi-finished products facilitates the handling and the reliable production of a material joining zone. The controlled material flow during the subsequent forming process also opens up completely new design possibilities of the resulting joining zone geometry, which cannot be created by conventional joining techniques. In addition, depending on the material combination, the (thermo-mechanical) forming process is expected to improve the joining quality. Based on different metallic materials it should thus be possible in the future to produce complex high-performance components which are not yet producible according to the current state of the art. The precedent joining process also results in manufacturing advantages. By means of the geometric adjustment of the joined semi-finished products to the final component a predistribution of the material is possible. As a result, the material flow and the process-related burr can be significantly reduced.

 

The topic of project C4 is the multiphysical modelling and simulation of the microstructural behaviour of the joining zone during the tailored forming process. The goal is the determination of the macroscopic, effective, thermomechanical properties of joining zones during and after forming. The macroscopic material model which will be developed here as well as the respective material parameters will be used by other projects within the collaborative research center e.g. for macroscopic forming simulations. One of the difficulties in modelling and simulating the microstructure of joining zones of different materials is the possibly very different behaviour of the joint materials. The joining zones sustain rather complex, strongly coupled mechanical, thermal and chemical influences during the joining and forming processes as well as during heat treatment. Diffusion plays an important role for the cohesion of the materials. On the microstructural level the polycrystalline material of the joining zone will be modelled (see Figure 1). The model will be able to capture the contact and diffusion processes during joining, the thermal and mechanical properties during forming as well as the material behaviour during heat treatment which is responsible for calibrating material properties. A second goal of the material modelling and simulation is the prediction of the material behavior and of eigenstresses after forming and in the vicinity of joint surfaces as well as close to machined surfaces. In close collaboration with other projects of the CRC 1153 the material models for the microstructure as well as the macroscopic material models will be validated. On the macroscopic level the material models will be used in a couple of other cooperating projects for forming simulations.