Minimum energy paths for unit advancement of a crack front are determined by reaction pathway sampling, thus providing the reaction coordinates for the analysis of crack tip mechanics in ductile and brittle materials. We compare results on activation energy barrier and atomic displacement distributions for an atomically sharp crack in Cu, where one observes the emission of a partial dislocation...

An understanding of the fatigue and fracture behavior of hard tissues (e.g., bone and tissues of the human tooth) is critical to the maintenance of physical and oral health. Recent studies suggest that there are a number of mechanisms contributing to crack extension and crack arrest in these materials, and that they appear to be a function of moisture and age of the tissue. An understanding of ...

Theories of toughness of materials depend on an understanding of the characteristic instabilities of the crack tip, and their possible interactions. In this paper we examine the effect of dislocation emission on subsequent cleavage of a crack and on further dislocation emission. The work is an extension of the previously published Lattice Greens Function methodology[1, 2, 3]. We have developed ...

Self-healing polymers, based on microencapsulated dicyclopentadiene and Grubbs' catalyst embedded in the polymer matrix, are capable of responding to propagating fatigue cracks by autonomic processes that lead to higher endurance limits and life extension, or even the complete arrest of the crack growth. The amount of fatigue-life extension depends on the relative magnitude of the mechanical ki...

It is demonstrated that the removal of material or the creation or extension of cracks always reduces the total potential energy of any non-linear or linear stable elastic body under fixed load and displacement boundary conditions. A weaker statement that crack extension releases potential energy in excess of plastic dissipation is established for stable elastic-plastic bodies, with certain str...

Based on the analytical solution of Crouch to the problem of a constant discontinuity in displacement over a finite line segment in an infinite elastic solid, in the present paper, the crack-tip displacement discontinuity elements, which can be classified as the left and the right crack-tip elements, are presented to model the singularity of stress near a crack tip. Furthermore, the crack-tip e...

Recent experiments revealed an exciting possibility of making nanowires by filling nanosacle cracks in a thin film. Exploration and practical application of the method would rely on the modeling capability to predict complex nanocracks and their geometries in heterogeneous films. This paper proposes a level set approach to investigate the formation of nanocrack patterns, which allows precise pr...

The crack growth resistance of human dentin was characterized as a function of relative distance from the DEJ and the corresponding microstructure. Compact tension specimens were prepared from the coronal dentin of caries-free 3rd molars. The specimens were sectioned from either the outer, middle or inner dentin. Stable crack extension was achieved under Mode I quasi-static loading, with the cr...

This paper briefly reviews progres~ in the elastic plastic analysis of crack extension. Analytical results for plane strain and plane stress deformation fields are noted, and elastic-plastic fracture instability as well as transitional behavior and combined rate and thermal effects are discussed.