摘要
利用脉宽30 ns的钕玻璃激光器对7050铝合金紧固孔进行激光冲击强化,采用先强化材料表面,再钻紧固孔的方式对双联疲劳试件进行强化,并在飞机中机身随机载荷条件下进行疲劳试验。试验结果表明:激光冲击强化后的紧固孔的疲劳寿命比未强化紧固孔的疲劳寿命提高1.5倍,强化后紧固孔的裂纹均起裂于次表层,且出现多个疲劳裂纹源。疲劳增益主要得益于激光冲击强化后紧固孔周围为残余压应力分布,强化表层的较小的冷作硬化程度,以及超高应变速率塑性应变引起的高密度位错,激光冲击强化技术可有效提高小尺寸紧固孔的疲劳寿命。
7050 aluminum alloy fastener holes were strengthened by laser shock peening with Nd：glass pulse laser and pulse duration 30ns. The means of hardening fastener holes were laser shock peening on the dog-bone fatigue specimens before drilling fastener hole on the center of shocked areas, then fatigue testing was carried out under random loading spectrum of plane. The data of experiments show that： the fatigue life of fastener hole on specimens via laser shock peening is 1.5 times higher than those without peening, and the fractures show multiple fatigue crack sources is located under the surface. The density of dislocation in treated surface case is much higher than base material, because of the ultra-high plastic strain during laser shock peening. Distribution of compressive residual stress, relative low degree of cold work and high-density dislocation are conducive to fatigue performance. The results of study show that the laser shock peening can effectively improve the fatigue life of small-size fastener hole.
出处
《应用激光》
CSCD
北大核心
2013年第3期259-262,共4页
Applied Laser
