CTOD Fracture Toughness Tests and Numerical Simulation for Welded Joints of Q370qE

Abstract

In this investigation, Based on BS7448 fracture toughness test experiment standard and DNV-OS-C401, three-point crack tip open displacement (CTOD) bending tests were made using Q370qE base steel, weld seam and heat-affected zone (HAZ) samples at different sample thicknesses and at different temperature to study the elasto-plastic fracture toughness of the materials frequently used in ocean engineering structure, and the results were calculated using the p-V curves. The results show that different CTOD values corresponding to the occurrence of brittle fracture before yield strength, brittle fracture after yield strength, and ductile fracture are related to different material types, thicknesses, temperature; and the CTOD value is made up of elastic part and plastic part, the value of plastic part greatly influence the CTOD value. Finally, using ANSYS commercial software, bending test models all of base steel, welded joint, HAZ with various center through crack sizes were computed by three-dimensional finite element method, from the results of the finite element analysis, the simulated p-V curve was obtained. It could be found that the simulated curve was close with the experimental curves, so the finite element analysis was accurate. And these works also have important project practical value to the ocean engineering structure designer.