Fracture-induced mechanochemical activation is achieved for the first time in a structural engineering polymer. Rubber toughened PMMA is lightly cross-linked (1.0 mol%) with the mechanophore spiropyran by free radical polymerization. Single Edge Notch Tension tests are performed on the spiropyran-linked material and a distinct change in color and fluorescence is detected at the crack tip, indic...

We report the first atomistic calculation of the saddle-point configuration and activation energy for the nucleation of a 3D dislocation loop from a stressed crack tip in single crystal Cu. The transition state is found using reaction pathway sampling schemes, the nudged elastic band, and dimer methods. For the (111)[110] crack, loaded typically at 75% of the athermal critical strain energy rel...

Earlier [ 1] we described an experimental procedure aimed at exarnining the spatial and temporal distribution of energy dissipation during crack initiation and propagation in a ductile polymer. The experiment combines a table-top tensile tester and an infrared imaging system. Because of the intense heating of the crack tip region, direct observation of the temperature rise not only provides an ...

In this work, the mechanism for fracture of brittle substances such as rocks under a uniform normal tension is considered. The oriented straight micro-cracks are mostly created in all the polycrystalline materials resulting from the stress concentrations. The present work focuses on the interactions of the pre-existing micro-cracks, which can grow and propagate within a rock-like specimen. The ...

Crack growth analysis has remained one of the challenging problems in the fracture mechanics of structures. On the other hand, the fatigue crack growth is a common phenomenon in the components of structures like airplanes, navies and fluid storages where the fracture due to crack should be considered in the design of these structures. In this paper, the finite volume method (FVM) is extended fo...

In this paper, the plates made of functionally graded material (FGM) with and without a crack are numerically simulated, employing the finite element method (FEM). The material property variations are defined to be fully continuous; therefore, the elements can be as small as required. For this purpose, variations of the material properties are applied in both the integration points and in the n...

Asymptotic near-tip fields are analyzed for a plane strain Mode I crack propagating dynamically in non-associative elastic–plastic solids of the Drucker–Prager type with an isotropic linear strain hardening response. Eigen solutions are obtained over a range of material parameters and crack speeds, based on the assumption that asymptotic solutions are variable-separable and fully continuous. A ...

The present paper explores quasi-cleavage processes driven by dislocation pileups against a Dislocation Free Zone (DFZ). The nanoscopic growth of the main crack consists of sequences of nanocrack formation in DFZ and its subsequent linkage with the main crack. Under mode I loading, the equilibrium locations of individual dislocations and the equilibrium number of dislocations are determined by ...

that varies with distance, r, from the crack tip as r 1 2 . In this paper, a traction free plane stress wedge with a discrete cohesive zone along the intended crack-path is studied. Of interest is the in uence of the cohesive zone on the crack tip stress eld. Further, the in uence of the cohesive zone on the strain energy release rate is also investigated. Two example problems are studied; a do...

Compressive failure by splitting is studied herein via an analytical model. The use of a shear lag model to determine the stress state at the crack tip and the modeling of the region away from the crack tip by the 3D elasticity equations leads to a simple analytical expression is used to determine the compliance changes for both unsteady crack growth as well as steady state crack growth under c...