Failure criterion for PA12 SLS additive manufactured parts

In order to use selective laser sintering to manufacture structural parts for automotive and aerospace applications, the failure conditions of such a component must be understood and predicted. A 3D failure criterion for anisotropic materials that incorporates stress interactions is implemented to predict failure of selective laser sintered parts manufactured using polyamide 12 powder. Special test specimens that capture tensile, compressive and shear strengths, as single or combined loads, were designed, manufactured and tested. Results show that significant differences exist between tensile and compressive strengths, and that failure of additive manufactured parts is strongly influenced by the interaction between stresses. The test data shows an excellent fit with a tensor based failure criterion that includes interaction strength tensor components, thus being able to capture the strength behavior of SLS printed components under complex loading conditions. The study also demonstrated that work is still required to allow incorporation of some important stress interactions present in those complex stress fields.