Topic
Fracture toughness
About: Fracture toughness is a research topic. Over the lifetime, 39642 publications have been published within this topic receiving 854338 citations.
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TL;DR: In this paper, the nanoindentation fracture of amorphous carbon films on silicon substrate was studied and the fracture process was found to progress in three stages: (1) first ring-like through-thickness cracks form around the indenter by high stresses in the contact area; (2) delamination and buckling occur around the contact areas at the film/substrate interface by high lateral pressure; and (3) second ring-wise through-thinness cracks and spalling are generated by high bending stresses at the edges of the buck led film.
270 citations
TL;DR: In this paper, a constitutive model for steady-state crack growth under plane strain conditions in small-scale yielding is presented, which is characterized by a generalization of JZ flow theory which accounts for the influence of the gradients of plastic strains on hardening.
Abstract: Mode I steady-state crack growth is analysed under plane strain conditions in small scale yielding. The elastic-plastic solid is characterized by a generalization of JZ flow theory which accounts for the influence of the gradients of plastic strains on hardening. The constitutive model involves one new parameter, a material length 1, specifying the scale of nonuniform deformation at which hardening elevation owing to strain gradients becomes important. Gradients of plastic strain at a sharp crack tip result in a substantial increase in tractions ahead of the tip. This has important consequences for crack growth in materials that fail by decohesion or cleavage at the atomic scale. The new constitutive law is used in conjunction with a model which represents the fracture process by an embedded traction-separation relation applied on the plane ahead of the crack tip. The ratio of the macroscopic work of fracture to the work of the fracture process is calculated as a function of the parameters characterizing the fracture process and the solid, with particular emphasis on the role of 1. 0 1997 Elsevier Science Ltd
269 citations
TL;DR: Aircraft grade epoxy-clay nanocomposites based on tetraglycidyl-4, 4′-diaminodiphenylmethane (TGDDM) cured with diaminodiphhenyl sulphone (DDS) were synthesized as discussed by the authors.
268 citations
TL;DR: In this paper, the surface modification process of carbon nanotubes was characterized by means of zeta potential measurements and TEM microscopy, and it was shown that the addition of only 0.1 wt % CNTs in the alumina composite increased the fracture toughness from 3.7 to 4.9 MPa·m1/2.
Abstract: Preparation of carbon nanotube (CNT)/alumina composites by a simple colloidal processing method has been reported in this paper. The surface modification process of carbon nanotubes was characterized by means of zeta potential measurements and TEM microscopy. The addition of only 0.1 wt % carbon nanotubes in the alumina composite increases the fracture toughness from 3.7 to 4.9 MPa·m1/2. Microstructure characterization, performed by SEM, showed that the bridging effect on cracks, the tight bonding between CNTs and alumina matrix, and the pullout of CNTs from matrix are possible mechanisms leading to the improvement of the fracture toughness.
268 citations
TL;DR: In this paper, the effect of heat treatment on the mechanical properties of Nb-Nb5-Si3 two-phase alloys having compositions Nb 10 and 16 pct Si (compositions quoted in atomic percent) was investigated.
Abstract: The effect of heat treatment on the mechanical properties of Nb-Nb5-Si3 two-phase alloys having compositions Nb-10 and 16 pct Si (compositions quoted in atomic percent) has been investigated. This includes an evaluation of the strength, ductility, and toughness of as-cast and hot-extruded product forms. The two phases are thermochemically stable up to ∼1670 °C, exhibit little coarsening up to 1500 °C, and are amenable to microstructural variations, which include changes in morphology and size. The measured mechanical properties and fractographic analysis indicate that in the extruded condition, the terminal Nb phase can provide significant toughening of the intermetallic Nb5Si3 matrix by plastic-stretching, interface-debonding, and crack-bridging mechanisms. It has been further shown that in these alloys, a high level of strength is retained up to 1400 °C.
268 citations