Evaluating the Mechanical Properties within the Transition Region of Multi-Material Large-Format Extrusion Additive Manufacturing

Abstract

Recent developments in Large-Format Additive Manufacturing (LFAM) have enabled in- situ material changes and production of graded Multi-Material (MM) structures. The Big Area Additive Manufacturing (BAAM) system utilizes a dual-hopper configuration to feed different materials into a screw-based extruder which results in a blended material transition rather than a discrete material boundary, avoiding associated delamination issues. While this system enables site-specific material deposition at a large scale, the mechanical performance within the transition region needs to be evaluated to determine the impact on end-part performance. Additionally, the transition region can exhibit incomplete mixing, which could further influence mechanical performance. This study investigates the change in mechanical properties throughout the transition region using dynamic mechanical analysis and tensile testing of printed samples. Optical microscopy of the internal microstructure of the printed beads was also utilized to determine the influence of material blending within the transition on mechanical performance.