Researcher(s)
- Matthew Nichols, Mechanical Engineering, University of Delaware
Faculty Mentor(s)
- Suresh Advani, Mechanical Engineering, University of Delaware
Abstract
This study, as a part of the ARPA program, aims to increase the interlaminar shear strength of additively manufactured composites. In this composite manufacturing process, continuous carbon fiber tows are pulled through an epoxy bath for resin impregnation. The fiber tow was then pulled through a metering device and a guide to control the amount of excess resin on the carbon fiber tow, and to align the continuous fiber. The fibers were then wound onto a rotating mandrel, into layers, under pressure from a compaction roller to form a consolidated laminate structure.
Multiple methods for increasing the interlaminar shear strength were proposed. One of the concepts was to incorporate thermoplastic particles between the layers, which would be melted during the curing of the epoxy. The thermoplastics would then reform, increasing the adhesion between the layers of carbon fiber. This study investigates the effect of thermoplastic polyurethane (TPU) particles on the interlaminar shear strength of carbon fiber-reinforced composites. The incorporation of TPU reduced the Short Beam Strength from 53.0 MPa to 28.9 MPa, aligning with the TPU’s ultimate strength, and indicating failure due to shearing at the particle interfaces. This demonstrates a clear correlation between thermoplastic particle inclusion and interlaminar performance. In the future, to improve the strength of the additively manufactured parts, stronger plastics should be used to increase the adhesion between the carbon fiber layers.
Future work will evaluate alternative thermoplastics such as Nylon 12, which offer significantly higher shear strength and a suitable melting point below 180 °C. These additional studies will not only be used to determine the best thermoplastic particle to be used in an additive manufactured carbon fiber composite, but to also further validate the correlation between particle inclusion and mechanical performance.