Fracture experiments of single silicon crystals reveal that after the critical fracture load is reached, the crack speed jumps from zero to approximately 2 km/sec, indicating that crack motion at lower speeds is forbidden. This contradicts classical continuum fracture theories predicting a continuously increasing crack speed with increasing load. Here we show that this threshold crack speed may...

objective : the aim of this study was to evaluate fracture characteristics of rigid two-tooth segments splinted with fiber reinforced composite (frc), with and without application of simulated masticatory forces. material and methods: in this experimental study, 80 extracted maxillary bicuspids were joined in pairs from the buccal aspect using frc. the specimens were divided into two groups. in...

abstract childhood and adolescence are critical periods for the skeleton. mechanical load has then been shown to be one of the best stimuli to enhance not only bone mass, but also structural skeletal adaptations, as both contributing to bone strength. exercise prescription also includes a window of opportunity to improve bone strength in the late pre- and early peri-pubertal period. there is so...

Stable ductile crack growth in 3 mm thick AISI 304 stainless steel specimens has been investigated experimentally and numerically. Multi-linear Isotropic Hardening method coupled with the Von-Mises yield criterion was adopted for modeling elasto-plastic behavior of the material. Mode-I CT fracture specimens have been tested to generate experimental load-displacement-crack growth data during sta...

Fracture damage in trilayers consisting of outer and inner brittle layers bonded to a compliant (polycarbonate) substrate and subjected to concentrated surface loading is analyzed. The principal mode of fracture is radial cracking at the undersurface of the inner (core) layer, even in the strongest of core ceramics--other damage modes, including radial cracking in the outer (veneer) layer, are ...

This paper presents the fracture analyses conducted on the FAA/NASA stiffened and unstiffened panels using the STAGS (STructural Analysis of General Shells) code with the critical crack-tip-opening angle (CTOA) fracture criterion. The STAGS code with the “plane-strain” core option was used in all analyses. Previous analyses of wide, flat panels have shown that the high-constraint conditions aro...

A two-dimensional fracture model where the interaction among elements is modeled by an anisotropic stress-transfer function is presented. The influence of anisotropy on the macroscopic properties of the samples is clarified, by interpolating between several limiting cases of load sharing. Furthermore, the critical stress and the distribution of failure avalanches are obtained numerically for di...

An experimental evaluation of mixed mode fracture tests conducted on adhesively bonded wood specimens using a dual actuator load frame is presented. This unit allows the fracture mode mixity to be easily varied during testing of a given specimen, providing improved consistency, accuracy, and ease of testing over a range of loading modes. Double cantilever beam (DCB) type specimens made of south...