摘要
根据Williams级数解,裂纹尖端应力场由Ⅰ-Ⅱ复合型应力强度因子及T应力共同控制。将裂纹尖端应力分量代入Von Mises屈服准则,建立裂纹尖端塑性扩展区模型。基于该模型获得了在不同Ⅰ-Ⅱ复合比断裂情况下裂纹尖端塑性扩展区形状随T应力的变化规律,并对Ⅰ型和Ⅱ型断裂在复合型裂纹断裂所占的比例、T应力大小及泊松比对塑性区域形状的影响进行了讨论。研究结果表明:正的T应力引起裂纹断裂角θ0减小,加剧裂纹扩展;负的T应力导致裂纹断裂角θ0增大,并抑制裂纹扩展;T应力为0或纯Ⅰ型裂纹尖端塑性区存在对称轴,存在T应力后,塑性区域呈不对称分布,T应力绝对值越大,塑性区域面积越大,T应力对裂纹尖端塑性区形状及尺寸大小均有很大影响。此外,不同Ⅰ-Ⅱ复合型裂纹,塑性区域面积均随泊松比的增大而减小。塑性区变化的观测结果对进一步分析加载条件下Ⅰ-Ⅱ复合型裂纹工程结构缺陷的疲劳和断裂具有重要意义。
According to Williams series solution,the stress field at the crack tip is controlled by the I-Ⅱ composite stress intensity factor and T-stress.The plastic propagation zone model of crack tip is established by substituting the stress component of the crack tip into Von Mises yield criterion.Based on the model,the variation laws of the shape of the plastic propagation zone at the crack tip with T-stress under different I-Ⅱ composite factors(Me)are obtained,and the influences of T-stress and Poisson’s ratio on the shape of plastic zone under different I-Ⅱ composite factors(Me) are discussed.The results show that the positive T-stress causes the crack fracture angle θ0 to decrease and aggravate the crack propagation;the negative T-stress causes the crack fracture angle θ0 to increase and restrain the crack propagation;the shape of the crack tip plastic zone is axisymmetric when the T-stress is 0 or fracture is pure I type crack,and it is nonaxisymmetric when the T-stress is not 0;T-stress has a great influence on the shape and size of the plastic zone at the crack tip,the greater the absolute value of T-stress,the larger the plastic zone.In addition,the area of the plastic zone of composite cracks with different composite factors(Me) decreases with the increase of Poisson’s ratio.The research results of this paper are of great significance for further analysis of fatigue and fracture of engineering structure with I-Ⅱ composite crack under loading.
作者
段国胜
DUAN Guosheng(Qinghai Communications Technical College,Xining,Qinghai 810000,China)
出处
《西安石油大学学报（自然科学版）》
CAS
北大核心
2020年第5期65-71,共7页
Journal of Xi’an Shiyou University（Natural Science Edition）
基金
青海东部地区公路泥石流特征及快速抢修技术研究项目(2018-ZJ-733)。
关键词
裂纹尖端塑性区
复合型断裂
T应力
应力强度因子
泊松比
plastic zone at crack tip
composite fracture
T stress
stress intensity factor
Poisson’s ratio
