Fused Filament Fabrication (FFF) has been on the forefront of AM due to the relatively low costs and broad availability of machines. However, parts produced by this technology tend to be highly anisotropic and usually underperform when benchmarked against objects produced by traditional plastic manufacturing techniques. These limitations imply that predicting part failure is paramount and yet extremely difficult, thus hindering the adoption of FFF in the production of parts destined towards highly demanding engineering applications in both the aerospace and automotive industries. A new failure criterion which includes stress interactions and developed with anisotropic materials in mind, was used in this study to develop a failure surface for FFF manufactured parts. A custom, in-house extruded filament was used to produce and test the failure of test coupons under a variety of conditions which include tensile, compressive and shear strengths, as well as strengths that include the effect of stress interactions. The specimens were printed using both a conventional FFF machine and one that makes use of a 6-axis robotic printer capable of producing bead orientations that cannot be achieved with conventional methods and that allow assessing stress interactions. With all the required strength tensor components, a strength analysis and evaluation of an FFF part can be performed.
- Apply the failure criterion shown to evaluate FFF parts
- Conduct the tests described to develop a failure surface for FFF parts