Most materials respond either elastically or inelastically to applied stress, while repeated loading can result in mechanical fatigue. Conversely, bones and other biomechanical tissues have the ability to strengthen when subjected to recurring elastic stress.
Now, researchers from Rice University and the Universidade Federal de Minas Gerais, Brazil, have reported that a nanocomposite responds to loads in a manner similar to bones, by self-stiffening in response to compression loads. The response of the vertically-aligned carbon nanotube/poly(dimethylsiloxane) nanocomposites is previously unseen in synthetic materials.
Interestingly, this self-stiffening behavior results in a permanent increase in stiffness that continues until the stress is removed, and resumes when the stress is reapplied. The effect is also specific to dynamic loads, similar to the localized self-strengthening that occurs in biological structures. The observations could lead to the development of adaptable structural materials and active, load-bearing artificial connective tissues.