Residual stress relaxation and progressive collapse behavior of butt-welded hull plates: Experimental study and numerical analysis

As the essential joining method, butt welding is highly utilized in the assembly of hull sections and blocks. The butt-welded hull plates with welding residual stress (WRS) and distortion may be subjected to cyclic loading over the lifespan of a ship, giving rise to residual stress relaxation and potential permanent plastic deformation. An experimental test is carried out in this paper to investigate the WRS relaxation of a transversely welded steel specimen. Based on the experimental data obtained in this paper and other work, the adopted three-dimensional sequential coupled thermal elasto-plastic FEM is verified. Subsequently, multi-pass welding simulation of hull plates with a transverse V-butt junction is conducted varying the plate thickness. Shakedown analysis and strength analysis are then performed using the resulting welding imperfections considering kinematic hardening and isotropic hardening. Characteristics of the welding imperfections as well as WRS relaxation and ultimate strength under different load patterns and amplitudes are elaborated, aiming to provide valuable insights for the safety assessment of hull sections.