Quantitative Evaluation of Micro Interfacial Behavior in Advanced Composites -A New Method for Intralaminar and Interlaminar Interfaces

针对具有层内和/或层间界面的高级复合材料，提出了双解理钻孔压缩（DCDC）试样。采用边界元法对试件的应力分布进行了分析。同时，对这些DCDC试样进行了试验，研究了裂纹扩展行为，并计算了不同界面下的界面断裂能。通过边界元分析，证实了中平面有孔偏移的DCDC试件具有混合模态应力分布，而没有孔偏移的DCDC试件具有I型应力分布。得到了任意尺寸试样的几何形状函数。将几何形状函数与实验结果相结合，形成了定量计算界面断裂能的方法。研究发现，II型对界面断裂能的影响随着井距的增大而增大。实验表明，DCDC试验是评价先进复合材料界面行为的一种有效方法。

A double cleavage drilled compression (DCDC) specimens have been proposed for advanced composite materials with intralaminar and/or interlaminar interface. The stress distributions for these specimens are analyzed using the boundary element method (BEM).At the same time, the experiments on these DCDC specimens were conducted in order to examine the crack propagating behavior and calculate the interfacial fracture energy with different interfaces.Using the BEM analysis, it was confirmed that the DCDC specimen with the hole offset from the mid-plane has a mixed-mode stress distribution, while it has the mode I without the hole offset. The geometric shape function is obtained for any size of specimen. Combining the geometric shape function with the experimental results, the approach to quantitatively calculate the interfacial fracture energy is formed. It is found that the effect of the mode II on the interfacial fracture energy become large when the value of hole offset increases. The experiments show the DCDC test is a useful method for evaluating the interfacial behavior of advanced composite materials.