FRACTURE PREDICTION ANALYSIS OF Q690D HIGH STRENGTH STEEL BASED ON CONTINUUM DAMAGE MODEL

High strength steel has been gradually applied in the steel structure constructions in recent years. Q690D high strength steel specimens were tested under monotonic loading and extremely low cyclic loading in the paper. The crack initiation locations of specimens were investigated and the effect of loading history on strength and deformation of notched specimens was analyzed. Scanning electron microscope revealed that the fracture morphology of specimens was a dimple pattern with the features of ductile fracture. Based on monotonic tensile test results of notched specimens and finite element analyses, the continuum damage model parameters of Q690D steel were calibrated. Finally, the continuum damage model was applied to predict fracture failure of notched coupon specimens and the specimens with initial gap under different loading conditions. It shows that the cracking location, load-displacement curves, fracture displacement and fatigue life obtained from the numerical simulation are in good agreement with the experimental results.