Enhanced large-scale analysis method and its application to multiaxial pipe weld

Abstract

A large-scale infrared ray telescope is to be built as a next-generation telescope. In this telescope, a large reflector is supported by a truss structure and welded joints that consist of multiple pipes. This paper investigates welding residual stress, which affects fatigue strength and static fracture strength. In the investigation, a novel large-scale analysis method for welding mechanics was developed based on an idealized explicit finite element method (FEM) using the multigrid method. To show the capability of the developed method, it was applied to a fundamental bead-on-plate problem. Residual stress distribution on a multiaxial pipe was studied by using the developed method. The analysis and measurement were compared to show the accuracy of the analysis, and the results showed that the shrinkage of each pipe and residual stress distribution were in good agreement. It was also found that subsequent welding may affect residual stress distribution if the parts being welded are close to each other and that the effect of subsequent welding is small if they are separated. The analysis was finished within almost 10 days. Therefore, the developed multigrid idealized explicit FEM can analyze the welding residual stress of complex structures in a realistic computing time.