纤维增强钛基复合材料界面剪切强度的FEM分析

FEM Modeling of Interfacial Shear Strength in SiC -Fibre Reinforced Titanium Matrix Composites

用薄试样push-out和push-back试验测试了SCS-6/Timetal834复合材料从室温到530℃温度范围内的峰值载荷和滑动摩擦切应力。用轴对称圆柱有限元模型模拟计算了SiC纤维增强钛基复合材料不同温度下的界面应力沿轴向分布规律和界面脱粘过程。计算表明,push-out试验的界面脱粘过程可以用剪切强度准则描述,对于SCS-6/Timetal834复合材料,当界面单元尺寸L=6.25μm时,其室温下界面剪切强度τm=500MPa,300℃时τm=300MPa,530℃时τm=140MPa。由于应力奇异性的影响,界面剪切强度的值与单元尺寸大小有关。

Push-out and push-back experiments of SCS-6/Timetal 834composites have been performed in the temperature r ange of room temperature to 530℃to measure the ma ximum load values and slip shear stre sses.On the basis of cylinder FEM mod el the interfacial shear stress distribution and the debondi ng process of composites for differe nt temperature range are modeled by f inite element method.It is found that the debonding process can be described by the shear strength criterion and the interfacial shear strength isτ m =500MPa at room tem-perature,τ m =300MPa at 300℃andτ m =140MPa at 530℃when the interfacial element length is 6.25μm.Since the stress field at crack tip is singular,the interfacial shear strength is dependent on the size of element.