Modeling and simulation of large, conformal, porosity-graded and lightweight lattice structures made by additive manufacturing

The emergence of additive manufacturing has enabled the design and manufacture of lightweight parts such as lattice structures with a complex geometry. However, conducting computer simulations to predict the mechanical behavior of such structures remains a challenge, especially when the number of struts is high. Firstly, this paper presents an approach to quickly build a lattice structure made of a large number of struts. The method takes advantage of the capabilities of finite element meshers to generate the tessellation of the volume into a series of tetrahedrons whose edges define the struts of the lattice. A graded-porosity can be defined during this process. Secondly, for the numerical simulation, the struts are modeled by beam finite elements. To adequately simulate the entire range of porosity, the material stiffness can be adjusted at any point of the structure, mainly to compensate for the lack of validity of stout beam elements. A numerical validation demonstrates the validity of the method by adequately predicting the displacement distribution of a mechanically loaded lattice structure, but an experimental validation raises issues related to the manufacturing limitations of small struts.