Interlaminar Reinforcement with Polymer Additive Manufacturing – Enhancing Fracture Toughness and Strength
Interfaces in polymer-based fiber reinforced composites are critical regions that are most susceptible to delamination under static and impact loads. Mechanical responses, like compression, bending, impact and combinatory loading on layered composites are affected by interface strength and toughness, geometry and the extent of loading. Debonding or delamination is observed to be a dominant failure mechanism in layered composites and is often accompanied by significant visible damage and reduction in mechanical properties. Thus, interface design is very critical for layered materials, like fiber reinforced composites, and structures like bonded joints, and an effort towards developing smart designing techniques to minimize the damage and failure incurred by weak interfaces has been a focus area in my lab.
Within this work, interfaces are engineered using mechanics information about crack propagation. Utilizing the concept of crack turning, we have achieved enhanced toughness at the interlaminar regions. A combination of computational modeling, additive manufacturing technology like fused filament fabrication (FFF) and experimental validation is used for enabling novel designs at these interfaces to obtain stronger composites that are less susceptible to interface failure. We introduce interface patterns by printing on fiber reinforced prepregs such that they form interlocking patterns. This causes cracks to steer around these patterns causing the interlaminar fracture toughness to increase.