Resistive Embedded Heating for Homogeneous Curing of Composite Damage Repair

Thesis (Ph.D.)--University of Washington, 2016-08The increased use of composite materials in passenger aircrafts has resulted in an escalation of maintenance issues associated with composite structure damage from a variety of causes including impacts during towing, bird strikes and hail. Hence, damage repair has become an important issue in the aerospace industry. This research aims to improve the performance of current composite repair technology by direct application of heat using an embedded heater in the bondline between the base laminate and the repair material rather than the use of surface heating such as using heatlamps or heat blankets. The use of surface heating can lead to large thermal gradients potentially resulting in improper cure. The proposed embedded heating can: (i) avoid large thermal gradients; (ii) lead to a more uniform cure of the adhesive during repair; (iii) improve performance metrics, including increased strength, stiffness; and (iv) reduce or eliminate thermal warping of the repaired structure. The goal of the proposed research is to enable an energy-efficient, adhesive-bonding approach for joining carbon-fiber composite components, which can lead to a new direction for advanced composites manufacturing. By localizing the heating to where it is needed, the proposed approach can substantially reduce the energy and cost of joining composite components when compared to the use of traditional methods such as using autoclaves