This paper describes the effects of the elastic modulus and sliding velocity on the friction and shear fracture of smooth silanized rigid disks rotating against thin confined films of poly(dimethylsiloxane) (PDMS) elastomers. A rigid glass disk is rotated against thin PDMS films of different thicknesses and moduli bonded to a glass plate at various speeds. While the disk rotates on the PDMS coa...

The process of nanocontact including indentation and retraction between a large Ni tip and a Cu substrate is investigated using quasicontinuum (QC) method. The multiscale model reveals that significant plastic deformation occurs during the process of nanocontact between Ni tip and Cu substrate. Plastic deformation is observed in an area as large as 20 nm wide and 10 nm thick beneath Ni tip duri...

Temperature dependent fracture properties of NiTi-based Shape Memory Alloys (SMAs), within the pseudoelastic regime, were analyzed. In particular, the effective Stress Intensity Factor (SIF) was estimated, at different values of the testing temperature, by a fitting of the William's expansion series, based on Digital Image Correlation (DIC) measurements. It was found that temperature plays an i...

fast fracture is one of the major failure modes in brittle polymers. generally, crack growth in these polymers may occur under combined tensile-shear loading. however, the fracture test data reported previously for some dental restorative resins can not be predicted by using the available fracture criteria.in this paper, a modified fracture criterion is used for estimating the fracture load for...

An earlier analysis of chipping fracture in brittle solids is here extended to include the case of blocks with inclined side faces and non-normal contact loading. The simple relation PF = βKch for the critical chipping load PF in terms of indent location h and material toughness Kc is preserved, with angular coordinates simply incorporated into the β coefficient. Chipping fracture tests using a...

the purpose of this ex- vivo study was to evaluate the fracture resistance of simulated immature teeth, obturated with gutta-percha or resilon and reinforced by either composite resin or fiber post.eighty-four human maxillary incisors were divided into seven groups (n=12). teeth in all groups were prepared until peeso #5 (1.5mm) could be passed through the apex. root ends received 4mm of mta pl...

in this study, first energy absorption of axial and bending loading is considered. next, thin walled structures under oblique loading are investigated using abaqus computer simulation, where 180 different cases are simulated. simulation results of the thin walled structures under oblique loading were compared with the experimental results of nagel, and good agreement was perceived. simulation r...

introduction: the resistance to fracture of endodontically treated teeth restored with esthetic post systems has not been extensively researched. this in vitro study compared the fracture patterns of endodontically treated teeth with esthetic post systems with different analysis methods. materials and methods: a total of 26 recently extracted human maxillary central incisors were decoronated an...

Mechanisms of femoral fracture of the condyles and shaft were experimentally investigated through controlled knee impact ofdenuded femurs in six human cadavers. High-speed movies recorded knee joint compression, femoral displacements and deformation, and fracture initiation. Fracture initiated at 10.6 + 2.7 kN knee load after 1.3 + 0.1 cm ofknec joint compression for a 10.1 kg rigid impact at 1...

This study evaluated the effect of zirconia framework design on fracture load of implant-supported zirconia-based prostheses after thermal cycling and mechanical loading. Three different zirconia framework designs were investigated: uniform-thickness (UNI), anatomic (ANA), and supported anatomic (SUP) designs. Each framework was layered with feldspathic porcelain (ZAC group) or indirect composi...