Bioinspired Interfaces for Improved Interlaminar Shear Strengthin 3D Printed Multi-material Polymer Composites

Additively manufactured soft-hard composite materials are significant because they combine the benefits of both soft and hard materials, creating a new class of materials with unique properties. The interfaces between the soft and hard phases are the most susceptible to failure and play a crucial role in fully utilizing the potential of each component in the composite material. This research introduces a new approach to improve the shear strength of interfaces in soft-hard polymer composites made using additive technology. The method involves designing and constructing a suture interface between the soft and hard polymers using the Fused Filament Fabrication (FFF) process. The overlap distance, a crucial parameter in the FFF method, is utilized to modify the size of the soft protrusions at the suture interface, resulting in improved interlaminar shear strength. The interface morphology is analyzed through microscopic evaluations of samples cut from the fabricated specimens, both in terms of quality and quantity. The interlaminar shear strength is measured using the short beam test method, and the failure process is further examined through digital image correlation measurements. The findings suggest that the interlaminar shear strength and interface stiffness gradually increases as the protrusion length grows. These results could serve as a useful reference for developing multi-material polymer composites with stronger and more resilient interfaces through additive manufacturing.