Rapid-Cure Liquid Shim

The U.S. DoD and several of our allies have designed and developed an advanced military fighter aircraft, the Joint Strike Fighter (JSF). During assembly, a liquid shim epoxy paste is applied before joints are mechanically fastened to make the joinedsurfaces fit tightly, thereby strengthening the joints and making them more durable. The current liquid shims provide excellent physical properties (particularly adhesive and compressive strength) but typically require 24 hours to develop a suitablehandling strength and up to 5-7 days for full cure at ambient temperature. Unfortunately, this long cure time results in a bottleneck for JSF manufacture. To remove the bottleneck, the JSF program requires a new liquid shim material that maintains theexcellent properties of the current materials but cures in less than two hours. TDA Research, Inc. (TDA) proposes to adapt our novel epoxy curatives to develop a high-strength, rapid-cure liquid shim. In this project, we will demonstrate feasibility bypreparing curatives, formulating them into rapid curing epoxy liquid shim pastes, and testing the shims' mechanical properties in accordance with Aerospace Material Specification 3726.