Ultrasonic Scarf Repair of Fiber-Reinforced Thermoplastic Composites

open_access
Open Access
Author:
Blyler, Katie
Area of Honors:
Aerospace Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Callie Zawaski, Thesis Supervisor
Puneet Singla, Thesis Honors Advisor
Keywords:
Thermoplastic
Composite
Repair
Ultrasonic Welding
Scarf Repair
Abstract:
The aerospace industry is beginning to adopt thermoplastic composites due to their ability to be reheated and reshaped, enable rapid, cost-effective manufacturing and provide enhanced impact strength. Their unique ability to be reheated and reshaped offers the potential for repair, however, currently there are no qualified repair methods for thermoplastic composites which use this ability. Instead, thermoplastics are being repaired using methods traditionally used for thermoset composites such as a bonded or bolted repair which often add weight and create stress concentrations. This paper demonstrates a repair method that adapts the scarf repair technique commonly used for thermoset composites, but uses heat generated via ultrasonic welding to reform and bond the matrix material, eliminating the need for thermoset adhesive. Damage was simulated using impact testing of a PEEK-carbon fiber panel. The damage was machined away and a matching patch was created to fill the damaged area using the same material. Then, the repair was performed by melting the interface between the patch, a sheet of thermoplastic film in between, and the panel using ultrasonic welding. Characterization of the repair was performed by using non-destructive ultrasonic scanning and destructive compression testing. The ultrasonic scanning showed that the ultrasonic welding could be used to repair the thermoplastic composites matrix.