A hybrid shape memory polymer filled metallic foam composite: shape restoring, strain sensing, Joule heating, strengthening, and toughening

In this paper, an open-cell metallic foam was filled in by a tough shape memory polymer (SMP), to form a hybrid metal/polymer composite with multifunctionalities and enhanced mechanical properties. This work aims to study the positive composite actions between the metallic skeleton and the SMP filler. Mechanical, thermal, and conductive properties of the resulting hybrid composite were evaluated and compared to the individual components. Uniaxial compression tests and shape memory effect tests were conducted. Results demonstrated an improvement in the compressive strength and toughness. The hybrid composite also exhibited excellent shape recovery and high recovery stress of 1.76 MPa. Infrared thermography has been used to verify the free shape recovery by Joule heating. Sandwich structures with the hybrid composite as the core were studied through low velocity impact test and three-point bending test. The sandwich structures with the composite foam core showed significant performance improvement in both tests. Electrical resistivity study during the three-point bending test validates the possible application of this multifunctional polymer-aluminum open cell foam composite as strain sensor. This type of hybrid composites can be beneficial in many industrial sectors that search for an ideal combination of high strength, high toughness, low weight, damage sensing, and excellent energy absorption capabilities.