Large-scale Thermo-Mechanical Simulation of Laser Beam Welding Using High-Performance Computing: A Qualitative Reproduction of Experimental Results

TL;DR

This work tackles solidification cracking in laser beam welding by combining CTW experiments with high-resolution thermo-elastoplastic simulations on HPC. A hybrid workflow links ANSYS for full-geometry thermal analysis with FE2TI, leveraging PETSc-based solvers and domain-decomposition preconditioners to achieve fully coupled thermo-elastoplasticity on millions of DOFs. The results show qualitative agreement with experimental strain patterns and localization behind the melt pool, while highlighting limitations from mesh dependence and microstructure neglect. The study outlines future directions in multiscale modeling and improved experimental input to move toward quantitative prediction of cracking phenomena.

Abstract

Laser beam welding is a non-contact joining technique that has gained significant importance in the course of the increasing degree of automation in industrial manufacturing. This process has established itself as a suitable joining tool for metallic materials due to its non-contact processing, short cycle times, and small heat-affected zones. One potential problem, however, is the formation of solidification cracks, which particularly affects alloys with a pronounced melting range. Since solidification cracking is influenced by both temperature and strain rate, precise measurement technologies are of crucial importance. For this purpose, as an experimental setup, a Controlled Tensile Weldability (CTW) test combined with a local deformation measurement technique is used. The aim of the present work is the development of computational methods and software tools to numerically simulate the CTW. The numerical results are compared with those obtained from the experimental CTW. In this study, an austenitic stainless steel sheet is selected. A thermo-elastoplastic material behavior with temperature-dependent material parameters is assumed. The time-dependent problem is first discretized in time and then the resulting nonlinear problem is linearized with Newton's method. For the discretization in space, finite elements are used. In order to obtain a sufficiently accurate solution, a large number of finite elements has to be used. In each Newton step, this yields a large linear system of equations that has to be solved. Therefore, a highly parallel scalable solver framework, based on the software library PETSc, was used to solve this computationally challenging problem on a high-performance computing architecture. Finally, the experimental results and the numerical simulations are compared, showing to be qualitatively in good agreement.

Figures (16)

• Figure 1: (Left) Instrumented CTW-test. (Right) Welding experiments under CTW-Test conditions-specimens arrangement.
• Figure 1: Temperature field and discrete representation of the melting pool using hexahedral finite elements.
• Figure 1: Schematic illustration of CTW test; the whole specimen was used for the ANSYS simulations, while the FE2TI simulations focus on the middle strip.
• Figure 1: Example of an overlapping domain decomposition of a portion of the thin metal plate into overlapping subdomains. The overlap is visible as the opaque region, while the non-overlapping domain decomposition is highlighted in magenta. Each subdomain is associated to a single MPI rank.
• Figure 2: FOV of the camera image