Q690D高强钢基于连续损伤模型的断裂破坏预测分析

高强钢材在实际钢结构中已经开始逐步得到应用，该文针对Q690D高强度结构钢材，进行了钢材圆棒试样在单调加载和超低周循环加载下的断裂破坏试验，研究了试样裂纹的起始位置，分析了加载制度对试样承载能力和变形能力的影响，并采用扫描电镜观察了试样断口的微观形貌，断口呈现韧窝形式的延性断裂特征。基于Q690D钢材缺口圆棒试样的单调拉伸试验结果，结合有限元分析，标定了钢材的连续损伤模型参数。最后，应用钢材的连续损伤模型，对圆棒试样和带初始间隙试样在不同加载制度下的断裂破坏进行预测分析，得到试样的裂纹起始位置、荷载-位移曲线、断裂位移和疲劳寿命均与试验结果吻合良好。

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.