Mechanical Instabilities: From Failure Mechanism to Functionality

Abstract Mechanical instabilities, phenomena in which solids and structures lose stability under external stimuli, were traditionally regarded as failure mechanisms but have recently been harnessed to design various functional structures and systems. Over the past century, significant progress has been made in both understanding the fundamental mechanisms behind mechanical instabilities and leveraging them for innovative functional applications. In this review, we classify mechanical instabilities into five categories based on their underlying failure mechanisms: buckling instability, snap-buckling instability, surface instability, buckling-driven delamination, and dynamic instability. First, a brief historical overview of research in this field is presented. Then, for each category of mechanical instabilities, we systematically introduce the underlying mechanisms and associated functional applications, with a particular focus on three fundamental aspects: the conditions under which instability is triggered, the evolution of the system after the onset of instability, and the strategies for exploiting these instabilities in functional design. Finally, we discuss several promising directions for future research. We expect that this review can help readers have a deeper understanding of mechanical instabilities and thereby inspire their broader application in advanced materials and structural systems.