Concurrent channel reinforcement: A novel reinforcing procedure for polymeric structures fabricated via material extrusion technique

Abstract

This study investigates the use of metallic macro-fiber with Concurrent Channel Reinforcement to improve the fracture resistance of polymeric parts made by material extrusion additive manufacturing. The research begins by evaluating the interfacial bonding strength between the embedded fibers and the polymer matrix, a critical factor affecting the effectiveness of the proposed method. Through a series of fiber pull-out tests, the impact of various in- and post-processing treatments on interfacial bonding strength is studied. Results show significant improvements in Interfacial Shear Strength (ISS) at fiber/matrix interfaces, with increases of 4491 % and 655 % attributed to in- and post-processing treatments, respectively. Subsequently, reinforced Semi-Circular Bend (SCB) specimens, treated with selected methodologies, are prepared and mechanically tested. Findings demonstrate substantial enhancements in fracture resistance, with the incorporation of 16 macro-fibers (0.53 % fiber volume fraction) alongside in- and post-processing treatments resulting in improvements of 26.1 % and 88.7 % relative to control counterparts. Additionally, Digital Image Correlation (DIC) analysis reveals a decrease in Notch Opening Distance (NOD) values due to improved mechanical properties of the polymer matrix facilitated by embedded metallic macro-fibers. Finally, fractography analyzes are performed on the tested specimens to provide insights into the surface characteristics of reinforcing fibers and micro-mechanisms of fracture, further clarifying the reinforcement mechanism.