激光冲击强化Al7050–T7451合金紧固孔的残余应力研究

Residual Stresses of Al7050–T7451 Alloy Fastener Holes With Laser Shock Peening

为研究不同激光冲击强化轨迹对Al7050–T7451合金紧固孔残余应力的影响,改善紧固件疲劳寿命,采用ABAQUS有限元模型和生死单元技术,对Al7050–T7451合金紧固孔开展先强化后开孔和先开孔后强化的残余应力数值模拟试验研究。研究结果表明,4个十字交叉光斑激光冲击强化Al7050–T7451合金表面S;残余压应力数值模拟结果接近试验测试值,先强化后开孔数值模拟结果与试验测试值接近,验证模型正确性。与先开孔后强化相比,先强化后开孔Al7050–T7451合金紧固孔的表面S;残余压应力值更大。与2个横向光斑相比,2个纵向光斑激光冲击强化紧固孔的表面S;残余压应力值更大。与2个光斑相比,4个十字交叉光斑激光冲击强化紧固孔的表面S;残余压应力值更大。研究结果为改善激光冲击强化紧固孔疲劳寿命奠定基础。

ABAQUS finite element model and life-death element technique were used to study the effects of different laser shock peening(LSP) paths on the residual stresses of Al7050–T7451 alloy fastener holes, which would improve their fatigue lives. Fastener holes were treated by LSP before and after opening holes by numerical simulation and test study. The results indicate that the simulation values of S;surface compressive residual stresses of Al7050–T7451fastener holes treated by LSP with four spots are close to the test values and the simulation values with hole after are close to the test values. It verifies the correctness of the model. Compared with hole before, the high S;surface compressive residual stresses are generated at the edge of Al7050–T7451 alloy fastener holes with hole after. Compared with the two transverse spots, the high S;surface compressive residual stresses are generated at the edge of Al7050–T7451 fastener holes treated by LSP with two longitudinal spots. Compared with two spots, the high S;surface compressive residual stresses are generated at the edge of Al7050–T7451 fastener holes treated by LSP with four spots. The results could lay the foundation for the fatigue extension of fastener holes with LSP.