Numerical modeling and testing of mechanical behavior of AM Titanium alloy bracket for aerospace applications

A key issue in designing a new product made through the Additive Manufacturing (AM) is the prediction of mechanical properties of material. Several experimental results show that AM-based products are often affected by widespread porosity, low density regions within their volume and anisotropy. Those effects are due to the manufacturing process, despite of efforts spent to improve the process parameters. This paper presents the numerical modelling of a geometrically complex structural bracket for aerospace application, which was re-designed through a topological optimization and produced in Ti-6Al-4V by means of the AM. The design activity herein described required to resort to a suitable model of constitutive properties of material by facing the problem of a large number of porosity/low density areas, as detected by a tomographic analysis of the mechanical component. According to some references an equivalent isotropic and homogeneous model of material was applied. Nevertheless the limitations of that approach were investigated through a validation of the numerical model and a testing activity. It was demonstrated that the Finite Element model based upon the assumptions of homogeneous and isotropic material might be effective in predicting the material and component strength, at least in static design, but even in case of design against fatigue, provided that a suitable experimental characterization of material was performed. The procedure of optimization was then assessed and compared to some preliminary tests performed on the real component, thus providing a preliminary good practice to the industrial partner involved in this research activity.