Advanced 3D printing techniques are enhancing fracture toughness in fiber-reinforced polymer composites, paving the way for high-durability applications across industries
Fiber-reinforced polymer composites (FRPCs) have emerged as key players across the aerospace, automotive and biomedical engineering industries as lightweight and resilient advanced materials. These industries demand high-strength, lightweight materials that can withstand substantial forces, whether in the wings of aircraft or the joints of a prosthetic limb. FPRCs, often crafted via 3D printing, offer impressive strength-to-weight ratios but are prone to weaknesses in fracture toughness due to the layered nature of additive manufacturing. However, recent research ǿմý significant advancements in fracture toughness, which promises to broaden the use of FRPCs across high-stakes industrial applications.
A team of researchers from Khalifa University, including Dr. Tayyab Khan, Dr. Murad Ali, Prof. Haider Butt, Prof. Rashid Abu Al-Rub, and Prof. Rehan Umer, collaborated with Zakia Riaz, Shanghai Jiao Tong University, China, and Yu Dong, Curtin University, Australia, to optimize 3D printing techniques for FRPCs. The team published their review in , a top 1% journal.
“FPRCs are manufactured by embedding fibers like carbon, glass, or even natural fibers into a polymer matrix,” Prof. Umer said. “This combination enhances mechanical properties such as tensile strength, flexibility, and fatigue resistance, creating materials suited for extreme conditions. Additive manufacturing allows them to be produced with lower waste and less expense, but 3D-printed FRPCs have historically been limited by weaknesses at their internal layer boundaries, which make them prone to delamination and cracking under stress.”
“From aerospace to medicine, by fine-tuning 3D printing parameters, we can greatly enhance fracture toughness in composites, making them viable for applications that demand both durability and flexibility.”
— Prof. Rehan Umer, Professor of Aerospace Engineering, KU
Studies show that higher temperatures lead to better bonding between layers in a 3D-printed composite and improved interfacial strength means that cracks are less likely to develop, significantly reducing the likelihood of delamination. Also, slower printing speeds increase the time for material bonding, producing stronger layers. Thicker layers reduce the number of inter-layer boundaries, making components more resistant to fractures that start between layers.
“Despite these advancements, manufacturing defects such as voids, cracks, and porosity remain a challenge for FRPCs,” Prof. Umer said. “Unintentional porosity, which can develop within layers or at layer boundaries, reduces mechanical strength and increases the likelihood of fractures. Techniques such as heat treatment and laser polishing can help minimize surface and internal voids, while printing in vacuum environments has also shown promise by reducing the porosity of FRPC components.”
The research team also pointed out that hybridization — embedding two types of fibers or combining two different polymers — can help achieve a balance of mechanical properties. Hybridization holds the potential to create materials with enhanced durability without sacrificing the customization sustainability advantages of 3D printing.
“Looking forward, additional research is needed to develop standards for evaluating the fracture performance of 3D-printed composites,” Prof. Umer said. “Current studies rely on general standards used for metallic or plastic parts, which may not fully capture the unique properties of additively manufactured composites. Establishing new standards could improve the reliability of 3D-printed components and further boost their adoption in critical applications.”
Jade Sterling
Science Writer
