NUMERICAL SIMULATION OF DUCTILE FRACTURE OF WELDED HOLLOW SPHERICAL JOINTS UNDER ECCENTRIC LOADINGS UPON VOID GROWTH MODEL

In single-layer lattice shell structures, welded hollow spherical (WHS) joints subject eccentric loadings. Ductile fracture and the corresponding ultimate load-carrying capacity of WHS joints under eccentric loadings cannot be determined with conventional FE analysis. The void growth model (VGM) was thusly adopted in ductile fracture analysis of WHS joints under eccentric loadings. The failure mechanism was clarified for WHS joints under eccentric compression and eccentric tension, respectively. The location and the ultimate load-carrying capacity of ductile fracture were rationally determined for WHS joints under eccentric tension. Considering the ultra-fine mesh requested by the VGM and the resulted low computational efficiency, a continuum damage model (CDM) based on the VGM was adopted in ductile fracture simulation of WHS joints under eccentric tension. A user subroutine was programmed to remove elements satisfying the fracture criterion during FE analysis. By comparison with results of the VGM, the applicability of the CDM in ductile fracture analysis of WHS joints was verified. The CDM allows ductile fracture simulation using FE model with relatively coarse meshes and therefore reduces the computational cost dramatically.