A physics-based failure study of smart artificial tissues in human-like soft robots

Abstract

Artificial tissues made of fiber-reinforced elastomers typically have mechanical properties similar to biological tissues. Such a similarity motivates artificial tissue usage in building human-like soft robots aiming primarily to perform a wide range of human-like motions and effectively interact with the human environment. Soft robots can be ripped or damaged for unknown reasons in a variety of applications. The literature has no unified stress-based criterion for predicting the critical zones of artificial tissues undergoing deformations. Such a unified stress-based criterion typically entails detecting internal damage and establishing the stress limit criterion based on the maximum stretching threshold. The current study establishes an experimentally validated rupture criterion for a novel class of smart artificial tissues made of electro-active polymers motivated by biological tissue damages in several robust conditions. A thermodynamically consistent mechanoelectrical deformation model is formulated, demonstrating that such tissues have inherent anisotropy that must be taken into account when modeling such materials. Later, a continuum physics-based rupture model is derived as a unified stress-based criterion to investigate the effect of physical parameters associated with artificial tissue failure. A well-known octahedral stress-based von Mises failure theory is adopted to examine all the principal deformation modes of artificial tissues up to rupture.