复合型裂纹应变能释放率逐点闭合的外推逼近研究

Research for the Strain Energy Release Rate of Complex Cracks by Using Point-by-Point Closed Extrapolation Approach

提出用外推逼近法计算复合型裂纹的应变能量释放率的新方法,闭合能计算时,采用逐点闭合的方法。避免了某些文献中闭合能计算不能自治的缺点:“当沿经向闭合节点多于两个时,裂纹(脱层)前端节点力乘位移已计算了闭合能,中间点还要重复计算闭合能”。具体计算了DCB(双悬臂梁)试件并与理论解进行了比较,吻合度优于其他方法。同时,又计算了紧凑拉伸试件、三点弯曲试件、单边裂纹试件,均取得满意结果。与理论解比较,误差可控制在1％之内。此方法可以广泛用于类似复合材料脱层裂纹的断裂力学分析。

A new extrapolation approach was proposed to calculate the strain energy release rates of complex cracks.The point-by-point closed method was used to calculate the closed energy,thus the disadvantage of self-inconsistency in some published papers can be avoided.The disadvantage is that the closed energy is repeatedly calculated: when closed nodal number along radial direction is more than two, the displacement of nodes behind the crack tip that is multiplied by nodal forces, the closed energy has been calculated and the crack surfaces have been closed,and that closed energy of middle point is calculated repeatedly.A DCB(double cantilever beam)specimen was calculated and compared with other theoretical results,it is shown that a better coincidence is obtained. In addition the same results are also obtained for compact tension specimen, three point bend specimen and single edge cracked specimen.In comparison with theoretical results,the error can be limited within 1 per cent. This method can be extended to analyze the fracture of composite laminates with various delamination cracks.