Reinforing Mechanism of Fiber-Reinforced Metals Considering Interfacial Stress Transfer

研究了界面剪切力学性能对SiC（SCS-6）纤维增强Ti-15-3合金基复合材料拉伸强度的影响。界面剪切力学性能的测量薄试样推出技术，在这项研究中开发的。界面剪切脱粘能量释放率约为10 J/m^2，剪切滑动应力为70-120 MPa，结合推出试验结果和有限元分析，得到了界面剪切滑动应力的来源，结果表明：界面剪切摩擦滑动主要来源于：（i）滑动界面的粗糙度，（ii）热致夹持应力，（iii）Poison约束效应。界面粗糙度取决于脱粘裂纹的相互作用产物和路径。对剪切摩擦应力的来源进行了定量分析，并从纤维、基体和界面的性质出发，从理论上得到了复合材料的拉伸强度。拉伸强度的理论预测与实验结果吻合较好。将得到的理论预测重新整理为“混合规则”的形式，以获得各种类型的纤维增强金属的抗拉强度。混合规则清楚地表明了界面剪切力学性能的影响和最佳界面剪切力学性能的存在，以获得最大强度的纤维增强金属基复合材料。

The effects of interfacial shear mechanical properties on the tensile strength of SiC (SCS-6) fiber-reinforced Ti-15-3 alloy matrix composites have been examined. The interfacial shear mechanical properties were measured by thin specimen pushout technique which developed within this study. The interfacial shear debonding energy release rate was about 10 J/m^2 and shear sliding stress was 70-120 MPa.The origin of interfacial shear sliding stress was also obtained using the pushout test results and FEA.The result showed that the interfacial shear frictional sliding originated from (i) roughness at sliding interface, (ii) thermally induced clamping stress, and (iii) Poison's constrain effects. The interface roughness depends on the rteaction products and path of the debonding crack. Quantitative understanding of the origin of shear frictional stress was also carried out.The tensile strength of the composite was obtained theoretically using the properties of fiber, matrix, and interface. The theoretical prediction of the tensile strength agreed well with the experimental results. The obtained theoretical prediction was re-arranged as a from of "rule of mixture" to obtain tensile strength of various types of fiber-reinforced metals. The rule of mixture clearly demonstrated effects of interfacial shear mechanical properties and existence of optimum interfacial shear mechanical properties to obtain a maximum strength of fiber-reinforced metal matrix composites.