There have been few studies to date describing fatigue-crack propagation thresholds under mixed-mode loading conditions in the presence of cracks, that are small as compared to the characteristic microstructural dimensions. To address this need, the variation in mixed-mode, high-cycle fatigue-crack growth thresholds with crack size is reported for a Ti-6Al-4V turbine blade alloy with a fine-gra...

Purpose: In the present paper a crack arrest model is proposed for an infinitely long narrow poled piezoelectric strip embedded with a centrally situated finite hairline straight crack. Design/methodology/approach: The ceramic of the strip is assumed to be mechanically brittle and electrically ductile. Combined mechanical and electrical loads applied at the edge of the strip open the rims of th...

The failure of materials and interfaces is mediated by cracks, almost singular dissipative structures that propagate at velocities approaching the speed of sound. Crack initiation and subsequent propagation-the dynamic process of fracture-couples a wide range of time and length scales. Crack dynamics challenge our understanding of the fundamental physics processes that take place in the extreme...

Vibrothermography, also known as Sonic IR and thermosonics, is a method for finding cracks through thermal imaging of vibration-induced crack heating. Due to large experimental variability and equipment which has, up to now, yielded mostly qualitative results, little data has been available to help quantify the vibrothermographic effect. This paper quantitatively evaluates the relationship betw...

A model has been developed to predict crack opening and closing behavior for propagating fatigue cracks which undergo significant sliding displacements at crack flanks. Crack surfaces were described statistically by assuming a random distribution of asperity heights and a mean density of asperities and asperity radii. The propagating crack was subdivided into strips, and each strip was treated ...

Quasi-static shear crack propagation in a linear elastic fluid-saturated porous solid c;Iuses a change of pore pressure on the crack plane if it is impermeable but not if it is permeable. Assuming that the pore pressure induced on the crack plane reduces the efTcclive compressive stress (total stress minus pore fluid pressure) and. as a result. the frictional resistance. we find that the energy...

The role of prism decussation on the crack growth resistance of human enamel is evaluated. Miniature inset compact tension (CT) specimens embodying a section of cuspal enamel were subjected to Mode I cyclic or monotonic loads. Cracks were grown in either the forward (from outer enamel inwards) or reverse (from inner enamel outwards) direction and the responses were compared quantitatively. Resu...

The nonlinear dynamic model of rotor-bearing-seal system with crack in shaft is set up based on the coupling model of nonlinear oil-film force and Muszyska’s nonlinear seal fluid force. The dynamic vibration characteristics of the rotor-bearing-seal system and the effects of physical and structural parameters of labyrinth seal and crack fault on movement character of the rotor were analyzed. Th...

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...

The opening profile of the cracks produced in the Double Cleavage Drilled Compression (DCDC) specimens for brittle materials is investigated. The study is achieved by combining Finite Element simulations of a DCDC linear elastic medium with experimental measurements by crack opening interferometry on pure silica glass samples. We show that the shape of the crack can be described by a simple exp...