1 Energy Absorption and Load Limiting via Extension- Torsion Coupled Stitch Ripping Composite Tubes

An innovative load limiting and energy absorbing device is presented here. The device is composed of concentric cylindrical composite tubes with opposite angles of fibers. The tubes are stitched together by a thread across the cross section and along the length. The tubes exhibit opposite extension-twist coupling. Upon being loaded axially, the tubes twist in opposite directions. Prior to their failure, the threads prevent relative rotation of tubes. This loads the threads in tension. At a certain limit load stitches begin to rip and energy stored in threads gets dissipated. The device is termed as tension-torsion stitch ripping device (TTSRD). The device exhibits variations in force-displacement characteristics, with changes in design and material parameters, resulting in wide range of available strokes and limit loads. Different material systems were analyzed and specific energy absorptions (SEAs) of the devices were compared. It was found that the presented device is capable of providing 2-3 times higher SEA than currently used devices for similar purposes. I