Considering inhomogeneous material properties for stiffness and failure prediction of thin-walled additively manufactured parts

Abstract

By overcoming manufacturing constraints imposed by traditional production technologies, additive manufacturing enables engineers to realize highly optimized lightweight components of unmatched geometrical complexity. However, the common dependency of the mechanical material properties on build orientation and wall thickness constitutes a challenge for valid structural analyses of thin-walled parts. Hence within this research, a previously proposed strategy to improve the structural simulations by mapping inhomogeneous material properties into finite shell element models is extended for failure prediction. Therefore, coupons in various build orientations and thicknesses were produced of short fiber-reinforced polyamid 12 via laser sintering and the mechanical properties evaluated by means of digital image correlation-assisted tensile testing. Consequently, the obtained data is utilized for modeling of the thickness dependent and anisotropic material behavior. The inhomogeneous material parameters are automatically mapped in the finite element models and ultimately, numeric simulations are validated by experimental testing of thin-walled parts. The comparisons of finite element analyses with mapped inhomogeneous and conventional constant properties disclosed considerably improved prediction of stiffness and failure. For the latter, however, substantial deviations between simulation and physical experiment remained, indicating that further research is necessary to effectively asses the load bearing capacity of thin-walled additively manufactured structures.