Analysis of a VARTM Repair for Composite Structure in Uniaxial and Biaxial Loading
The Sikorsky CH-53K Super Stallion Helicopter, under development for the United States Marine Corps, is the successor to the CH-53E and features substantial performance improvements made possible through the adoption of a hybrid composite airframe structure. The use of composite components on an aircraft is not a new idea; however for helicopters, their use presents unique challenges. As a result of their low speed and low-altitude operating environment, helicopters are particularly susceptible to damage from the environment in the form of foreign object damage and small arms fire. In order to keep the fleet operational and capable of supporting troops on the ground, any damage sustained during a mission must be able to be repaired quickly; preferably without the need to take the aircraft off of the front lines and back to an approved repair depot. Currently, no viable field level repair method has been standardized for use with composite structures. Purdue University has developed a repair technique, utilizing Vacuum Assisted Resin Transfer Molding (VARTM), that is applicable for field level repairs. Work through 2011 demonstrated the viability of this repair method under shear loading and also worked to characterize the strength of the bond between the existing, undamaged structure and the VARTM patch. The focus of this work is to provide further validation of the repair technique under uniaxial and biaxial loading conditions. The VARTM repair technique developed has been shown to be effective in restoring strength to a damaged panel in both uniaxial and biaxial loading conditions. Additionally, the capability to accurately predict the response and subsequent failure of the repaired panel under loading, through the use of a finite element model, has been developed and validated against experimental results.
Pipes, Purdue University.
Aerospace engineering|Materials science
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