Crack Growth Simulation at Welded Part of LNG Tank

Abstract

The objective of this research is to evaluate crack growth
behavior from a surface crack to a through crack in a liquefied
natural gas (LNG) tank. Crack growth behavior is analyzed by
superposition version FEM (S-FEM). As a crack grows, part of
the local mesh crosses over the global mesh. In S-FEM, the local
mesh is defined as existing in the global mesh. When a part of the
local mesh crosses over the global mesh, the Young’s modulus of
the part is made small to ignore the influence of the part. In this
way, the stress distribution of the local mesh is improved. In this
study, crack growth behavior under a tensile cyclic load is
analyzed. After crack penetration, the crack shape becomes
rectangular. Crack growth behavior under tensile bending loading
is also analyzed by simulating the four-point bending test. In this
simulation, the crack shape becomes trapezoidal after penetration.