Accepted Wednesday Sep 02, 2009
Materials fail by recurring rupture and shearing of interatomic bonds at microscopic, molecular scales, leading to disintegration of matter at macroscale and a loss of function. In this article, we review the state-of-the-art of investigations on failure mechanisms in materials, in particular focusing on atomistic origin of deformation and fracture and relationships between molecular mechanics and macroscale behavior. Simple examples of fracture phenomena are used to illustrate the significance and impact of material failure on our daily lives. Based on case studies, we discuss mechanisms of failure of a wide range of materials, ranging from tectonic plates to rupture of single molecules, and explain how atomistic simulation can be used to complement experimental studies and theory to provide a novel viewpoint in the analysis of complex systems. We illustrate how biological protein materials achieve extraordinary properties through intricate structures where the interplay of weak and strong chemical bonds, size and confinement effects, and hierarchical features play a fundamental role. This leads to a discussion of how even the most robust biological material systems fail, leading to diseases that arise from structural and mechanical alterations at molecular, cellular and tissue levels. We discuss new research directions in the field of materials failure and materials science and the impact of improving the current understanding of materials failure for applications in nanotechnology, biotechnology, medicine as well as the built environment.