Title: Enabling Assembly and Repair of Dissimilar Thermoplastic Composites for Space Applications via Ultrasonic Welding

Authors: Emily Friedman, Madeline Krzystowczyk, Genevieve Palardy

DOI: 10.33599/nasampe/s.25.0129

Abstract: The need to repair or reuse thermoplastic composite (TPC) materials is of growing concern, particularly for lightweight space structures in a lunar environment. Ultrasonic welding (USW) applies vibration at the joint to create heat, which enables assembly and potentially, repair. An energy director (ED) can be used to concentrate the vibration at the interface by quickly absorbing the energy and melting. In this work, dissimilar ED materials are used to assemble and repair ultrasonically welded joints to determine the effect of different melting temperatures on failure modes. Single lap shear joints were created using carbon fiber/polyether ether ketone (CF/PEEK) laminates with polyphenylene sulfide (PPS), PEEK, and polyethyleneimine (PEI) films as EDs. The welding force was varied (500 N and 1000 N) to assess its influence on lap shear strength (LSS). The same was done for the vertical displacement (40% and 60% of the ED’s thickness). Samples welded at 1000 N and 40% displacement were significantly stronger than those welded at 500 N and 40% displacement, owing to their interlaminar fracture. PEEK and PEI films at 1000 N yielded LSS of 29.4 MPa and 30.1 MPa, respectively. The samples were rewelded and underwent fractographic analysis to assess their repairability, failure modes, and strength recovery. Overall, the strength recovery by the third weld (repair cycle 2) ranged between approximately 25% and 50% of the original strength, with PPS 500 N maintaining the most of its original strength.

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Conference: SAMPE 2025

Publication Date: 2025/05/19

SKU: TP25-0000000129

Pages: 10

Price: $20.00