OBJECTIVES The aim of this study was to compare the mechanical properties of various nickel-titanium (NiTi) files with similar tapers and cross-sectional areas depending on whether they were surface-treated. MATERIALS AND METHODS Three NiTi file systems with a similar convex triangular cross-section and the same ISO #25 tip size were selected for this study: G6 (G6), ProTaper Universal (PTU),...

AIM To compare the effect of brushing motion on torsional and cyclic fatigue resistance of TF Adaptive instruments after clinical use. METHODS 20 packs of TFA small sequence (SybronEndo, Orange, CA, USA) were used for this study and divided into two groups. Each instrument prepared one resin tooth, consisting in 4 canals with a complex anatomy. In group A, no brushing motion was performed. In...

in this research, the influence of bolt preload on the fatigue strength of 2024-t3 aluminium alloy double lap bolted joints has been studied experimentally and numerically. to do so, three sets of the specimens were prepared and each of them subjected to tightening torque of 1,2.5 and 5 n-m and then fatigue tests were conducted under various cyclic axial load levels. in the numerical method, th...

The aim of this study was to investigate the effect of 50% hydrofluoric acid (HF) surface treatment on the cyclic fatigue resistance (CFR) of K3 NiTi instruments. Twenty as-received and twenty HF-treated K3 NiTi instruments were compared in CFR. The surface texture and fracture surface of two instrument groups were examined with a scanning electron microscope (SEM). Additionally, any change of ...

Nickel-base superalloys have become the key materials of hot-end components in the aeroengines over the past several decades. Nickelbase superalloys are easy to produce thermo-mechanical fatigue (TMF) behavior when withstanding the combined effects of high temperature, creep, oxidation, mechanical stress and thermal stress. The occurrence of TMF seriously affects the normal service for hot-end ...

In recent decades, the application of fibre-reinforced polymer (FRP) composites for strengthening structural elements has become an efficient option to meet the increased cyclic loads or repair due to corrosion or fatigue cracking. Hence, the objective of this study is to explore the existing FRP reinforcing techniques to care for fatigue damaged structural steel elements. This study covers the...

The aim of this work is to determine the fatigue life of 316L stainless steel. The mechanisms of fatigue of 316L stainless steels were investigated and discussed. The fatigue tests were carried out at constant-amplitude cyclic loading with load ratio R=0.1. Scanning Electron Microscope (SEM) is then used to examine the fracture surface. The results show that the fatigue limit of 316L stainless ...

The aim of this study was to comparatively evaluate the bending resistance at 45º, the static and dynamic cyclic fatigue life, and the fracture type of the WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) 25-08 and Reciproc (VDW, Munich, Germany) 25-08 instruments. A total of 60 nickel-titanium (NiTi) instruments (30 Reciproc and 30 WaveOne) from three different lots, each of which was 25 ...

The tensile fatigue properties of the collagen fibre meshwork in normal human articular cartilage were measured by subjecting isolated specimens of post-mortem femoral head cartilage to cyclic tensile stress. The results of the study showed (1) that the collagen fibre meshwork is fatigue prone and (2) that its fatigue strength decreases rapidly with age. Extrapolation of the data to physiologic...

In the present study, a general probabilistic design framework is developed for cyclic fatigue life prediction of metallic hardware using methods that address uncertainty in experimental data and computational model. The methodology involves (i) utilization of fatigue tests data conducted on coupons of Ti6Al4V material (ii) continuum damage mechanics based material constitutive models to simula...