Repair of thermoplastic composite aircraft structures
Abstract
The driving force behind the increased use of thermoplastic materials in fixed-wing aircraft (transports, business jets, general avi ation, fighters, etc.), rotorcraft, UAVs, and missile systems are their superior impact toughness, excellent thermal stability, fire /smoke/toxicity performance and, with the exception of PEI, chemical resistance. Further, despite the higher raw material costs comp ared to thermosets, the costs of the finished component can be lower due to reduced handling, processing and assembly costs. The pos sibility of re-melting thermoplastic composites is also often reported as a beneficial feature when repairing thermoplastics. And in deed, thermoplastics do offer great added potential for repair of delamination damage which can be restored by melting and re-consol idating instead of cutting out the entire damaged area. However, due to high processing temperatures and, depending on the manufactu ring process, high pressures it can be stated that repair techniques are less mature for thermoplastic composites than for conventio nal thermosetting composites.In this project two types of repair are investigated. These are reconsolidation of the original structu re in case of minor damage and removing part of the structure and replacing it with a patch for structures sustaining more severe da mage. In case of reconsolidation the damaged area is locally melted using an external heat source and the layers in the composite ar e fused together by applying pressure. For the patch type of repair the interface of the original structure and the patch are locall y melted using an induction welding and a resistance welding process. The repairs are supported by simulations predicting the heat a ffected area, possible distortions of the base structure and provide a guideline on the most optimum process parameters.Being able t o repair damaged thermoplastic structures will prevent costly replacement parts and increase durability, life extension, sustainment and readiness of any vehicle using thermoplastic airframe parts. The outcome of the research is not platform specific and can be ap plied to current, new-build and future next-generation designs and vehicles. Therefore it aligns with the focus area Power Projecti on and Integrated Defense as described in the US Naval S&T Strategic Plan 2015 (Affordability/Reduced Platform Life-Cycle Cost, Str uctural Materials and Materials, Computation and Prediction) and with the Marine Corp S&T Strategic Plan AVN STO-18: Composite mater ials in expeditionary environments which pursues to enhanced capability to rapidly make repairs to composite structures.The desired outcome of the research project will be a technical report, physical welded demonstrators, a conference presentation and simulation tools and models.Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 07, 2021
- Source ID
- N629092112051
Entities
People
- Senne Sterk
Organizations
- National Aerospace Laboratory
- Office of Naval Research
- United States Navy