TOWARDS MORE REALIZABLE RECYCLED CARBON FIBER REINFORCED COMPOSITES MANUFACTURING

This study includes a broad review of recycling processes of carbon fiber reinforced composite materials in the aerospace industry. It includes the pros and cons of current recycling processes as it applies to the end products manufactured in this industry by using the recycled carbon fibers blended with conventional thermoset or innovative thermoplastic polymers. A key limitation of recycled carbon fibers is the loss of interfacial adhesion arising from mechanical damage and sizing removal during recycling, accompanied by altered preform permeability. This may lead to increased production defects and a negative effect on the mechanical properties of end products. Thus, a framework to improve the interfacial adhesion of the recycled carbon fibers is presented after the overview of the recycling methods. In addition to the degradation in interfacial adhesion on the surface of carbon fibers during recycling processes, the topology of carbon fiber fabrics is also distorted. Previously long or continuous fibers are chopped into short pieces in mechanical processes required prior to any scalable thermal or chemical treatment. Therefore, recycled carbon fibers are used in non-woven mat forms instead of woven fabrics. These new topologies cause deviations in the permeability behavior of reinforcements compared to their previous woven forms. To better understand the permeability behavior of the non-woven mats made of recycled carbon fibers, a case study that investigates the effect of the short fiber properties on permeability by investigating their statistical variation in length, orientation and fiber volume fraction distributions is conducted. In this analysis, the well-established CFD solver Ansys Fluent is used. Ultimately, this study aims to provide insights into process modeling of recycled carbon fiber reinforced composite materials, with the aim of manufacturing parts with desirable mechanical characteristics.