Crack propagation of PMMA in some liquid environments is described for various testing conditions, such as fixed load, fixed displacement and monotonically increasing displacement. Fracture mechanics concepts have been used successfully in analysing the results. When continuous stable cracking is achieved, values of fracture toughness (R) for PMMA under these loading conditions are obtained as ...

We evaluated the effect of water storage on fluoride release and mechanical properties of compomer restorative material. Fluoride release was recorded using a specific fluoride electrode. Flexural properties and fracture toughness were measured using a universal testing machine. Vickers hardness was measured using a micro-hardness tester. There was initial burst of fluoride release up to 1 w, w...

The cleavage fracture toughness of steels was mezzo-scopically analyzed on the basis of the statistical local fracture criterion approach. The statistical stress criterion at the crack tip region suggests that the cleavage fracture toughness in steels can be described as a function of the yield stress, the cleavage fracture stress, and other mechanical properties of the materials. Formulation o...

the basic trait in the ceramics is their high brittle or low fracture toughness, and the main criteria in the design and application is specifying the fracture toughness in ceramics. in this paper, a new method is proposed to determine the fracture toughness of ceramics, which is enhanced in lowering the cost of fracture toughness determination relative to the previous methods. hence due to the...

INTRODUCTION: One of the most important properties of implant materials for joint arthroplasty is their wear resistance. Because of their excellent wear properties, ceramic materials have found application in particular in total hip arthroplasty; however, brittle failure remains a serious problem. Basic research has thus been focused on nacre, a natural composite consisting of imbricated aragon...

Bioactive glass ionomer cements (GICs) have been in widespread use for ∼40 years in dentistry and medicine. However, these composites fall short of the toughness needed for permanent implants. Significant impediment to improvement has been the requisite use of conventional destructive mechanical testing, which is necessarily retrospective. Here we show quantitatively, through the novel use of c...

A sound knowledge of mechanical properties of rocks at high temperatures and pressures is essential for modelling volcanological problems such as fracture of lava flows and dike emplacement. In particular, fracture toughness is a scale invariant material property of a rock that describes its resistance to tensile failure. A new fracture mechanics apparatus has been constructed enabling fracture...

The effect of prepolymerized particle fillers on fracture toughness of four commercial composite resins was studied. The ground surface morphology was examined with a field emission scanning electron microscope. Fracture toughness was determined by using single edge notched specimens. Acoustic Emission (AE), which is the elastic wave due to the release of energy from the localized sources of ma...

The effect of bleaching on fracture toughness (Kic) of existing composite-dentin interfaces was assessed using the notchless triangular prism (NTP) specimen fracture toughness test. Human molars and premolars (<6 months old) were wet ground on 600 SiC to obtain 4x4x4x4mm triangular prisms with buccal or lingual exposed for bonding. Buccal or lingual dentin surfaces, ground on 600 grit sandpaper...