What type of energy does 'Resilience' in materials refer to?

Resilience in materials specifically refers to the ability to absorb elastic energy when they are deformed under stress and then release that energy upon unloading. This property is crucial for materials that need to endure dynamic loads or impacts, as they can return to their original shape without sustaining permanent deformation.

While other properties such as thermal expansion, permanent deformation, and potential energy are important in materials science, they do not capture the essence of resilience. Thermal expansion involves changes in size or volume due to temperature variations, while permanent deformation indicates a loss of elasticity and the material's inability to return to its original state. Potential energy stored in a material generally pertains to conditions under which forces are applied but does not directly reflect the material's capability to recover from elastic deformation. Thus, the focus on elastic energy absorption and recovery is what rightly defines resilience.