TC4-DT钛合金结构二次冷挤压强化数值模拟与实验研究
Numerical and Experimental Study on TC4-DT Titanium Alloy Structure after Double Cold Expansion

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。
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