Enhanced Bonding via Additive Manufacturing‐Enabled Surface Tailoring of 3D Printed Continuous‐Fiber Composites

Abstract

Additive manufacturing (AM) of composites, particularly continuous fiber composites as studied here, is emerging as a new paradigm for creating advanced structures. Traditional machining and joining approaches will evolve or be fully displaced by AM approaches, and here the authors introduce a seminal investigation into AM‐enabled bonding/joining of continuous fiber composite laminates/multilayers. The AM‐enabled tailoring approach volumetrically increases surface area available for bonding by ∼150% by printing lines of continuous Nylon matrix filaments at an infill density of 50% to create a porous (∼50 vol%) bonding surface, rather than the conventional/baseline solid (100 vol%) surface approach. The AM‐tailored multilayers show improvements relative to the baseline single‐lap‐joint (SLJ) multilayer, and versus the industry‐standard surface preparation approach: 550% and 145% increases in ultimate strength, 10 000% and 800% increases in toughness, respectively, while maintaining joint stiffness. Benchmark mechanical performance data is established via the AM‐tailored bonding approach for carbon, glass, and Kevlar continuous fiber reinforced additively manufactured composite SLJ multilayers. AM‐enabled enhanced joining, such as the concept demonstrated here, is critical as AM components are increasingly being joined, both to each other and to other (non‐AM, different AM, etc.) structures in advanced applications.