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合金基复合材料抗拉强度的影响。采用本研究开发的薄试件推出技术对界面剪切力学性能进行了测试。界面剪切脱粘能释放速率约为10 J/m^2，剪切滑动应力为70 ~ 120 MPa。通过推拔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，界面剪切摩擦滑动的原因主要有：(1)滑动界面粗糙度，(2)热诱导夹紧应力，(3)毒物约束效应。界面粗糙度取决于反应产物和剥离裂纹的路径。对剪切摩擦应力的来源也进行了定量的了解。利用纤维、基体和界面的性能，从理论上得到了复合材料的抗拉强度。拉伸强度的理论预测与实验结果吻合较好。将得到的理论预测结果按照“混合规律”重新整理，得到了不同类型纤维增强金属的拉伸强度。混合规律清楚地表明界面剪切力学性能对纤维增强金属基复合材料的影响，并且存在获得最大强度的最佳界面剪切力学性能。

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.