Numerical and Experimental Study on TC4-DT Titanium Alloy Structure after Double Cold Expansion

Lubin Huo,Yuejie Cao,Zengqiang Cao,Fan Zhang

doi:10.1051/jnwpu/20183640701

Abstract

Cold Expansion and Interference Fit are two well-known techniques in hole strengthening, having been widely used in aviation industry. Double cold expansion is a new strengthening process which effectively combined with the two techniques. A modelling method based on ABAQUS finite element method is proposed in order to study the effect of double cold expansion, which will include cold expansion, reaming process, interference fit and springback after that, the influence of edge distance ratio (EDR) on the stress-strain distribution has been studied. Proto-LXRD device has been used to measure the residual stress distribution in the surface of the specimens. Simulation and experimental results show that the stress distribution of the simulation is in an higher level than that of experimental, but the trends of the stress distribution are in a good agreement.

Highlights

a new strengthening process which effectively combined with the two techniques
A modelling method based on ABAQUS finite element method is proposed in order to study the effect of double cold expansion
experimental results show that the stress distribution of the simulation is in an higher level

Summary

Introduction

西北工业大学学报 Journal of Northwestern Polytechnical University https: / / doi.org / 10.1051 / jnwpu / 20183640701 摘要:冷挤压和干涉配合作为飞行器制造中 2 种主要的孔强化工艺,可有效提高结构的疲劳寿命。二次冷挤压强化作为以上 2 种强化工艺的结合,具有较单一强化更好的强化效果,但其强化机理尚不清晰,从而限制了这一先进工艺的有效应用。提出了一种用于研究二次冷挤压强化机理的数值建模方法,并根据 TC4⁃DT 钛合金耳片孔二次冷挤压强化的实际工艺流程,综合考虑了开缝衬套冷挤压、铰孔、压合衬套干涉配合及回弹等过程,同时研究了边距比对二次冷挤压强化耳片孔周应力分布的影响,并采用 X 射线残余应力测量设备测量试件表面的残余应力。通过测量结果与模拟结果的对比表明:采用该建模方法得到的残余应力变化趋势与实验测量结果具有良好的一致性,可用于二次冷挤压强化机理的深入研究。目前针对复合强化机理的相关研究多数是以实验的方式进行,周期长、费用高、在工程应用中受到诸多限制。同时,在文献[ 9⁃11] 研究中均是在冷挤压后通过紧固件直接挤压孔壁形成干涉来实现复合强化的,这必然会造成孔壁损伤,且干涉量越大,损伤越严重。在实际的飞机装配连接中往往采用开缝衬套冷挤压加压合衬套干涉配合的新型复合强化工艺-二次冷挤压强化工艺,这样就避免了紧固件与孔壁的直接接触,从而减轻了安装过程中孔壁的损伤程度。身的连接部位。因此,本文将基于有限元数值模拟软件 ABAQUS,以耳片为研究对象,综合考虑二次冷挤压强化操作过程中的开缝衬套冷挤压、铰孔、压合衬套干涉配合及回弹,提出一种用于研究二次冷挤压强化机理的建模方法,分析二次冷挤压强化试件残余应力的分布情况,同时采用 X 射线衍射方法测量强化后试件的残余应力,并进行偏差分析,以验证建模方法的可靠性。

Results

Conclusion