NASA Langley Research Center has developed technology to increase the adhesive strength between shape memory polymer composites (SMPs) and metal alloys. Shape memory materials, including SMPs, have been explored for numerous applications because of their unique shape memory capabilities. These materials can change shape and/or other properties in response to changes in an external stimulus such as stress, temperature, or an electric field.
Initially developed for use in an adaptive wing structure, this NASA technology is a method to enhance the bond strength of SMPs that are joined to structural metal alloys. The method utilizes toughening and coupling agents to create better cohesion within the SMP, and better adhesion between the SMP and metal alloy at the material interface, thus reducing the possibility of fracture leading to catastrophic failure. Tests have shown this innovation to more than double the adhesive strength between an SMP and a metal alloy when compared to a non-modified system.