平行于功能梯度材料夹层的币型裂纹起裂条件

分析了功能梯度材料中币型裂纹的扩展问题．裂纹平行于无限域中功能梯度材料夹层，受有与裂纹面成任意角度的拉应力．假定功能梯度材料夹层与两个半无限域均匀介质完全粘合，其弹性模量沿厚度方向变化．采用基于层状材料广义Kelvin基本解的边界元方法分析裂纹问题，给出了均布正应力和剪应力作用下裂纹的应力强度因子、将应力强度因子耦合于应变能密度断裂判据，讨论了裂纹体在拉伸应力作用下的起裂条件．

GROWTH OF PENNY-SHAPED CRACK PARELLEL TO GRADED INTERFACE OF BIMATERIALS UNDER INCLINED TENSION

Growth of a penny shaped crack under an inclined tension is analyzed by considering the effect of functional graded materials. The crack is parallel to the functionally graded interfacial zone between two fully bonded solids. The functionally graded material is treated as a nonhomogeneous solid layer with its elastic modulus varying in the thickness direction. A generalized Kelvin solution based boundary element method is first employed for the calculation of the stress intensity factors. The crack surfaces are subject to either uniform normal traction or uniform shear traction. Via the superposition principle, the stress intensity factors are determined by taking into account the effects of the nonhomogeneity parameter and thickness of the functionally graded interfacial zone, as well as the crack distance to the zone. The stress intensity factors are then incorporated into the strain energy density fracture criterion for the prediction of crack growth. And the effects of external load directions, material and geometrical parameters on the critical loads are examined in detail.