锪窝圆角半径对CFRP/Al机械连接结构力学性能影响

Influence of Countersink Fillet Radius on Mechanical Performance of CFRP/Al Bolted Joints

碳纤维增强复合材料(CFRP)和铝合金(Al)因其优异的机械/物理性能,广泛应用于新一代商用飞机.CFRP/Al沉头螺栓连接结构是重要的连接形式,其中锪窝圆角半径影响了机械连接性能.研究中设计制造不同锪窝圆角的钻锪一体刀具对锪窝圆角尺寸进行控制,并采用基于复合材料渐进损伤模型的有限元仿真方法对不同锪窝圆角半径连接结构力学性能进行仿真和试验研究,分析了CFRP/Al叠层机械连接失效机理.结果表明,利用钻锪一体锪窝钻头可以有效控制锪窝圆角;锪窝位于CFRP层相比于位于铝合金层有着更大的极限强度;CFRP和铝合金材料均在锪窝圆角半径为1.0 mm时具有最大的极限载荷,即锪窝圆角略大于螺栓圆角有利于获得更好的机械连接性能.

Carbon fiber reinforced polymer(CFRP)and aluminum alloys(Al)are widely used in the new generation of commercial aircraft due to their excellent mechanical/physical properties.CFRP/Al countersink bolted structures are important connection forms,where the radius of the countersink fillet affects the mechanical connection performance.The countersink fillet radius is an important factor affecting the mechanical performance of bolted joints.In this paper,the countersink fillet radius is controlled by specially-designed drill-countersink tools with different countersink fillet radii.Meanwhile,the finite element model based on the progressive damage method of composite material is established and utilized to simulate the mechanical performance of different composite/metal bolted joints.The failure mechanism of CFRP/Al bolted joints is analyzed.The results show that the countersink fillet radius can be effectively controlled by specially-designed drill-counterbore tools.The ultimate strength of bolted joints with dimple in the CFRP layer is higher than that in the aluminum alloy layer.In terms of the countersink fillet radius,both CFRP and aluminum alloy materials have the maximum strength when the countersink fillet radius is 1.0 mm.That is,the countersink fillet radius should be slightly larger than the bolt fillet radius,which is conducive to a better mechanical performance.