Numerical simulation of the out-of-plane displacement during Cold-Expansion of Titanium plate

International audienceThis study deals with the cold-expansion process of a Ti-6Al-4V plate, investigated with the use of finite element simulation. Widely used in the aerospace industry, cold expansion of metallic holes aims towards improving the fatigue performance of metallic holes. Indeed, by providing compressive residual stresses in the hole surrounding, crack growth rate can be significantly decreased resulting in fatigue life improvements. However, little attention has been devoted to the prediction of the out-of-plane displacement near the hole wall. Perceived as problematic, further machining and surfacing are carried out upon cold-expansion in order to avoid material bump while maintaining the fatigue life as high as possible. Thus, in order to anticipate the depth of the removed layer, the cold-expansion process was simulated in 3D using Abaqus FEA software. The mechanical properties of the Ti-6Al-4V have been obtained from compression experiments at ambient temperature and at strain rates ranging from 0.1 to 10 s-1. To describe the compression behaviour, the Johnson-Cook flow stress model has been used. Carried out implicitly, the effects of tool velocity, lubrication, plate thickness and degree of cold expansion have also been studied. Combined with experimental measurements, the predictions of out-of-plane displacement have shown good geometric agreement. In the future, prediction of distortions and fatigue life is necessary. This will be accomplished by combining the present model with a damage model in order to establish a relationship between cold-expansion and fatigue life