聚乙烯Ⅰ-Ⅱ复合型疲劳裂纹扩展实验研究  

Experimental Study on theⅠ-ⅡMixed Mode Fatigue Crack Growth in Polyethylene

作　　者：钱杨帆 陈特 陈一铭 杨凤鹏[1] QIAN Yangfan;CHEN Te;CHEN Yiming;YANG Fengpeng(School of Naval Architecture,Ocean and Civil Engineering,Shanghai Jiao Tong University,Shanghai 200240,China)

机构地区：[1]上海交通大学船舶海洋与建筑工程学院,上海200240

出　　处：《力学季刊》2021年第1期87-97,共11页Chinese Quarterly of Mechanics

基　　金：国家自然科学基金(11102107);上海市自然科学基金(16ZR1417700)。

摘　　要：本文采用中密度聚乙烯(MDPE)单边斜切口板状试样,完成了多种条件下的Ⅰ-Ⅱ复合型疲劳裂纹扩展试验。通过对裂尖和裂尖银纹区演化的全程显微测量,获取了各试样疲劳裂纹扩展过程的一致性特征,其过程分为初始银纹区萌生、银纹区转向、裂纹宏观扩展三个阶段。通过计算发现最大周向拉应力准则能精确预测第一阶段初始银纹区的萌生角度。试验表明第二阶段中银纹区发生转向,且第三阶段中裂纹始终沿垂直于外载荷方向的路径扩展,该现象通过银纹机理结合对裂尖奇异场的分析得到了解释,并从断面分析中得到印证。对比不同加载角下试样的裂纹扩展过程,发现裂纹萌生时间随加载角增大显著增长,但裂纹扩展特征一致。TheⅠ-Ⅱmixed mode fatigue crack growth experiments were performed on MDPE plate specimens.The unanimous features of fatigue crack growth in these specimens were obtained by microscopic measurement of the crack tip and the craze zone.The crack growth process was divided into three stages:the craze zone initiation,the changing of the direction of craze zone,the crack propagation.The maximum tensile-strain(MTS)criterion was proved to be applicable for predicting the initial craze zone angle.The phenomenon that the crack growth route was always perpendicular to the loading direction was explained by the analysis of the crack tip stress singularity and the craze zone mechanism.The fracture surface was analyzed to confirm this explanation.The craze zone initiation time was increased sharply with the increase of loading angle,while the crack growth features were nearly the same.

关 键 词：聚乙烯 复合型裂纹扩展 银纹区 最大周向拉应力准则 断面分析 

分 类 号：O346.2[理学—固体力学]