This paper describes the development of a dual-actuator loading device that was then used to apply asymmetric, transverse end-displacements to laminated beam specimens (silicon/epoxy/silicon) over a range of separation rates. Measurements of the reaction forces, as well as load-point displacements and rotations, were used to determine the normal and tangential components of the crack tip displacements and the corresponding components of the J-integral. This was made possible because the specimens identically satisfied a balance condition. The resulting data set obtained from experiments conducted at five separation rates at each of five mode-mix phase angles is a testimony to the efficiency of the approach. A mixed-mode beam on elastic foundation analysis established that the stiffness of the normal and shear interactions of the silicon/epoxy interface was independent of the separation rate and mode-mix. Furthermore, the stiffness values thus determined were considerably lower than those based on the bulk behavior of the epoxy in tension and shear. The analysis also allowed the crack growth to be tracked in order to establish its onset and the corresponding critical values of the normal and shear components of the J-integral, along with the corresponding strengths and critical crack tip displacements. For each mode-mix, these critical values increased with the separation rate. This increase in properties is in spite of the glassy nature of the bulk epoxy and further suggests the presence of an interphase region in the epoxy adjacent to the silicon. However, the change of mode-mix was accompanied by a change in local separation rates, leading to non-monotonic behavior in the critical J-integral. Following the onset of crack growth, the application of the transverse end-displacements along radial loading paths resulted in simultaneous changes in the local separation rates and mode-mix, implying a fracture criterion that depends on both mode-mix and rate-dependent damage evolution processes.

本文介绍了双驱动器加载装置的开发，该装置随后用于在一定范围的分离速率下将不对称的横向端部位移应用于层压梁试样（硅/环氧树脂/硅）。反作用力以及载荷点位移和旋转的测量值用于确定裂纹尖端位移的法向和切向分量以及 J 积分的相应分量。这是因为试样完全满足平衡条件。从在五个模式混合相位角中的每一个以五个分离速率进行的实验中获得的结果数据集证明了该方法的效率。弹性基础上的混合模式梁分析表明，硅/环氧树脂界面的法向和剪切相互作用的刚度与分离速率和模式混合无关。此外，由此确定的刚度值明显低于基于环氧树脂在拉伸和剪切下的整体行为的刚度值。该分析还允许跟踪裂纹扩展，以确定其起始点和相应的 J 积分法向和剪切分量的临界值，以及相应的强度和临界裂纹尖端位移。对于每种模式混合，这些临界值随着分离率的增加而增加。尽管本体环氧树脂具有玻璃状性质，但性能的这种增加进一步表明环氧树脂中与硅相邻的相间区域的存在。然而，模式混合的变化伴随着局部分离率的变化，导致临界 J 积分的非单调行为。在裂纹扩展开始后，沿径向加载路径应用横向端部位移导致局部分离速率和模式混合的同时变化，这意味着断裂准则取决于模式混合和速率相关的损伤演化过程。