Study of improvement of fatigue strength safety and weight reduction by laser peening treatment in aircraft component materials

赋予机械结构以高的功能特性，对减轻机械结构的重量、节能和提高机械结构的疲劳强度可靠性具有重要意义。在本研究中，激光喷丸（LP）处理进行航空构件材料，如铝合金，钛合金和不锈钢。提高疲劳强度的可靠性，明确疲劳强度可靠性提高的机理是本研究的目的。主要研究结果如下：（1）在本研究所用的所有材料中，均证实了LP处理提高了疲劳强度，其提高效果是由LP处理在材料表层产生的高残余压应力和应变硬化引起的。LP处理改善了预裂纹材料对疲劳裂纹扩展的抑制作用。这些效应也是由LP处理产生的残余压应力和裂纹尖端塑性变形的裂纹闭合效应引起的。从这些结果可以看出，LP处理对于提高飞机部件材料和其它机器和结构的疲劳强度可靠性和减轻重量是非常有用的。

It is very useful for the reducing of weight and the energy reduction, and the high efficiency to improve the fatigue strength reliability of machines and structures by giving high functional property. In the present study, the laser peening(LP) treatment is performed on aircraft component materials such as Al alloy, Ti alloy and stainless steels. And it is the proposes of the research to improve the fatigue strength reliability and to make clear the mechanism of the improvement. The main results are as followings, (1)In all materials used in this study, it is confirmed to improve the fatigue strength by the LP treatment, and it is clear that the improvement effects are induced from the high compressive residual stress and the strain hardening in the surface layer of the materials by the LP treatment. The restrained effects for fatigue crack propagation process are improve the pre-cracked materials by the LP treatment. And, these effects are also induced from the compressive residual stress and the crack closure effects by plastic deformation near crack tip by the LP treatment. From these results, it is clear that the LP treatment is very useful for the fatigue strength reliability improvement and the weight reduction of the aircraft component materials and other machines and structures.