变刚度铺放改善单钉双剪螺栓连接拉伸强度

沿最大主应力方向的变刚度铺放可有效提高复合材料构件的强度。以与孔周围设定区域内,单元格上流场速度矢方向与有限元得到的最大主应力方向之间的差异最小为优化目标,优化有势流场构造参数,从而得到优化的变刚度铺层轨迹。该方法得到的变刚度铺层能最大程度地使纤维主方向与层合板在该点处的最大主应力方向一致。研究结果表明,变刚度铺放不仅可提高层合板的拉伸强度,还可使试件在达到极限载荷后的承载能力下降速度平缓,从而降低了发生瞬时性损坏的概率。

TENSILE STRENGTH IMPROVEMENT OF SINGLE BOLT DOUBLE SHEARING BY VARIABLE STIFFNESS PLACEMENT

The variable stiffness placement along the direction of the maximum principal stress can enhance the strength of composite laminate.By focusing on the area around the hole,the optimization objective is defined as the minimization of the directional difference between the velocity vectors at the cells in the flow field and the maximum principal stress obtained by the FE.Based on this optimization objective,the optimum parameters of the flow field are calculated.Then the tape paths on the variable-stiffness ply are determined,what are consistent with the direction distribution of the maximum principal stress as far as possible.The comparative experiments of the laminates show that the average ultimate tensile strength of the variable stiffness laminates was increased.Moreover,the declining of the load bearing capability of the variable stiffness laminates is slowing when the tensile load exceeds the ultimate strength,which reduces the occurrence rate of instantaneous failure.