Metal-ceramic nanocomposites are promising candidates for applications necessitating light weight and excellent fatigue resistance. We produced Mg–SiC from mechanically milled powders, yielding a homogeneous nanocrystalline structure quasistatic strength values. Little is known, however, about the behavior of such composites. Here, we used load increase tests on macroscale to yield estimation v...

ÐTransient cyclic fatigue-crack growth behavior following variable-amplitude loading sequences has been investigated in a hot-pressed, monolithic Si3N4 ceramic (NTK EC-141), for which fracture toughness (resistance-curve) and cyclic fatigue properties are well characterized. Following rapid changes in the applied stress-intensity range, DK, during both low-high and high-low block-loading sequen...

In this paper we examine the conditions for surface topography evolution and crack growth/fracture during the cyclic actuation of polysilicon microelectromechanical systems (MEMS) structures. The surface topography evolution that occurs during cyclic fatigue is shown to be stressassisted and may be predicted by linear perturbation analyses. The conditions for crack growth (due to pre-existing o...

INTRODUCTION Cyclic fatigue is the common reason for breakage of rotary instruments. This study was conducted to evaluate the effect of cryogenic treatment (CT) in improving the resistance to cyclic fatigue of endodontic rotary instruments. METHODS AND MATERIALS In this in vitro study, 20 RaCe and 20 Mtwo files were randomly divided into two groups of negative control and CT. CT files were st...

Fatigue failures caused by cyclic stresses are commonly modeled by Birnbaum-Saunders (B-S) and Weibull distributions. Sometimes, materials with high cycle fatigue exhibit bimodal failure rates which are difficult to model with Weibull distribution. The objective of this paper is to investigate a general Birnbaum-Saunders (GB-S) distribution which covers diverse hazard rates such as increasing, ...

We employ periodic density functional theory to explore the effect of cyclic tensile loading on the behavior of alumina in the threshold region of crack formation. We find evidence for nanoscale fatigue when the alumina lattice is subjected to uniaxial tensile loading and unloading and tensile stresses normal to the applied load. It is possible that such atomic-scale fatigue impacts the durabil...

This report presents the case of a patient in whom hip resurfacing arthroplasty failed because of loosening of the acetabular shell secondary to debonding of the surface coating. During normal function, there will inevitably be cyclic shear stress between the coating and the surrounding bone. This might result in fatigue failure of the bond. In spite of increasing numbers of porous coated aceta...

The fatigue properties of an extruded Mg–3Al–0Mn magnesium alloy component were evaluated experimentally. Fully reversed, strain control fatigue tests were conducted on specimens extracted from regions with a varying grain size and texture. Scanning electron microscopy was employed to establish structure–property relations between microstructure and cyclic damage. Relations were drawn between m...

Aircraft turbine engines routinely experience the ingestion of debris resulting in “foreign object damage” or FOD. Failures associated with foreign object damage have been estimated to cost the aerospace industry $4 billion per year. Often, FOD does not lead to sudden catastrophic failure, yet such damage can dramatically reduce the lifetime of components subjected to cyclic fatigue stresses. T...

Keywords: AL7075-T6 alloy Ti–TiN coating PVD magnetron sputtering Surface roughness Fuzzy logic Fretting fatigue a b s t r a c t In this study, the fretting fatigue resistance of AL7075-T6 alloy is investigated using surface treatment Ti–TiN multilayer coating by physical vapor deposition (PVD) magnetron sputtering technique. A fuzzy logic model was established to forecast the surface roughness...