A HALF-PLANE CRACK propagates dynamically, nominally in the x direction. along the plane _V = 0 in an unbounded solid subjected to remote loading equivalent to a static stress intensity factor K*. The crack front at time t lies along the arc x = c,,t+a_/‘(z, t) where a,) is a constant velocity, J’(z, t) is an arbitrary function, and E is a small parameter. The crack front speed thus varies alon...

We study the average velocity of crack fronts during stable interfacial fracture experiments in a heterogeneous quasibrittle material under constant loading rates and during long relaxation tests. The transparency of the material (polymethylmethacrylate) allows continuous tracking of the front position and relation of its evolution to the energy release rate. Despite significant velocity fluctu...

This paper presents a methodology for conducting a 3-D static fracture analysis with applications to a gas turbine compressor blade. An open crack model is considered in the study and crack-tip driving parameters are estimated by using 3-D singular crack-tip elements in ANSYS . The static fracture analysis is verified with a special purpose fracture code (FRANC3D). Once the crack front is perfe...

The tearing and healing of a one-dimensional crack in a solid, in the presence of external tectonic forces, pre-stress, static friction, cohesion and dynamic friction is investigated. It is found that cohesive forces have a strong influence on the velocity of rupture; the velocity of rupture is always less than or equal to the velocity of sound. The extension of the crack ceases either when the...

We address the simulation of dynamic crack propagation in brittle materials using a regularized phasefield description, which can also be interpreted as a damage-gradient model. Benefiting from a variational framework, the dynamic evolution of the mechanical fields are obtained as a succession of energy minimizations. We investigate the capacity of such a simple model to reproduce specific expe...

We compare experimental observations of a slow interfacial crack propagation along an heterogeneous interface to numerical simulations using a soft-clamped fiber bundle model. The model consists of a planar set of brittle fibers between a deformable elastic half-space and a rigid plate with a square root shape that imposes a non-linear displacement around the process zone. The non-linear square...

The propagation of an interfacial crack along a heterogeneous weak plane of a transparent Plexiglas block is followed using a high resolution fast camera. We show that the fracture front dynamics is governed by local and irregular avalanches with very large size and velocity fluctuations. We characterize the intermittent dynamics observed, i.e., the local pinnings and depinnings of the crack fr...

Dynamic fracture in a wide class of materials reveals a "fracture energy" Gamma much larger than the expected nominal surface energy due to the formation of two fresh surfaces. Moreover, the fracture energy depends on the crack velocity, Gamma=Gamma(upsilon). We show that a simple dynamical theory of viscoplasticity coupled to asymptotic pure linear elasticity provides a possible explanation to...

The propagation of cracks in layered glass from low-velocity impact of sharp or spherical tip projectiles is observed using high-speed photography. Tests are also carried out to determine the threshold impact energy for chipping in glass blocks and subsurface crack instability in an edge-supported glass plates. The results identify the median and subsurface radial crack systems as the prime dam...

We study experimentally the slow growth of a single crack in a glassy film of polycarbonate submitted to uniaxial and constant imposed load. Flame-shaped macroscopic zones of plastic deformation appear at the tips of the crack and the formation of these plastic zones involves a necking instability. In order to understand the crack growth dynamics, we study first the growth dynamics of the plast...