钛合金耳片结构复合强化工艺参数匹配研究

PROCESS PARAMETER MATCHING RESEARCH ON COMPOSITE STRENGTHENING OF TITANIUM ALLOY LUG STRUCTURAL

为了提高航空耳片结构疲劳性能,建立TC4钛合金耳片孔开缝衬套冷挤压与干涉配合复合强化有限元模型,分析了复合强化工艺参数对孔周塑性变形及结构疲劳寿命的影响。设计耳片孔周残余应力测试试验,验证了模型的准确性。复合强化工艺参数的研究结果表明:孔壁材料随芯棒的塑性流动使孔壁变形量在厚度方向上分布不均,弹塑性边界随挤压量的增长向耳片外侧转移;交变载荷下应力幅值的最大值始终位于孔壁处,且入口处应力水平最高;针对TC4钛合金耳片结构,3%挤压量与1%干涉量的复合强化工艺参数组合,疲劳寿命增益效果最好。

In order to improve the fatigue performance of the aviation lug structure,a finite element(FE)model of composite strengthening process which contains cold expansion and interference fit has been established.The influence of technological parameters on plastic deformation around hole and fatigue life of lugs has been analyzed.The residual stress test around the lug hole was carried out to verify the accuracy of the FE model.The results indicate that the plastic flow of the hole wall material with the mandrel makes the deformation of the hole wall unevenly distributed in the thickness direction.And the elastic-plastic boundary transfers to the outer side of the lug with the increase of the expansion amount.Further research shows that the maximum stress amplitude is always located at the wall of the hole and the mean stress level is the highest at the entrance when the lug structure is subjected to alternating loads.For the structure of TC4 titanium alloy lug,the increment of fatigue life can reach the maximization when the process parameters consist of 3%cold expansion and 1%interference fit.