Residual stress present in coupons used for fracture testing will influence the experimental determination of fracture toughness. Triaxial residual stress (e.g., due to welding) can alter both the driving force for fracture and the crack-tip constraint at a specified load, so that the apparent toughness of a coupon depends on the residual stress present. In this paper, we employ a micromechanic...

The purpose of this study was to compare the properties of 2 new dual-cure, bulk-fill restorative composite resins to those of a hybrid composite resin material. Depth of cure, fracture toughness, porosity, microleakage, and volumetric shrinkage properties were examined. With the exception of fracture toughness, significant differences were found among materials. Compared to the incrementally p...

The effects of temperature and loading rate on delamination growth were studied. The delamination fracture toughness of IM7/K3B was measured at 149°C, 177°C, and 204°C. At each temperature the tests were performed with a variety of loading rates so that the delamination initiated over the range of time from 0.5 sec to 24 hrs. The double cantilever beam (DCB) test was used to measure fracture to...

Recently, biomaterials-based tissue engineering strategies such as hydrogels have offered great promise in repairing articular cartilage. Mechanical failure testing in outcome analyses is given the crucial clinical importance to the success of engineered constructs. Interpenetrating networks (IPNs) are gaining more attention due to their superior mechanical integrity. Extensive fracture toughne...

UNLABELLED The objective of this study was to investigate the correlation between filler size, fracture toughness and voids. Seven model resin composites and one commercial have been used in the study. A single edge notch mould was used to prepare samples (n=8). A selected area of 1mm below and above the notch was scanned with micro CT and then the percentage of voids calculated. A universal te...

Recently, a new generation of titanium aluminide alloy named Gamma-Met PX (GKSS, Geesthacht, Germany) has been developed with better rolling and postrolling characteristics. Previous work on this alloy has shown the material to have higher strengths at room and elevated temperatures when compared with other gamma titanium aluminides. In particular, this new alloy has shown increased ductility a...

The structural reliability of many brittle materials such as structural ceramics relies on the occurrence of intergranular, as opposed to transgranular, fracture in order to induce toughening by grain bridging. For a constant grain boundary strength and grain boundary toughness, the current work examines the role of grain strength, grain toughness, and grain angle in promoting intergranular fra...

STATEMENT OF PROBLEM The fabrication of zirconium dioxide (ZrO2) dental prosthetic substructures requires an extended sintering process (8 to 10 hours) in a conventional oven. Microwave sintering is a shorter process (2 hours) than conventional sintering. PURPOSE The purpose of this study was to compare the fracture toughness of 3 mol % Y2O3-stabilized ZrO2 sintered in a conventional or micro...