conclusions regarding the study limitations, dentinal cracks were observed in all files and distances from the apex. although there was more crack incidence in protaper files, no significant differences were noted regarding the studied systems and sections from the apex. materials and methods in an experimental in vitro trial, 80 maxillary and mandibular first molars were selected and their cro...

The influence of ultrasonic nanocrystal surface modification (UNSM) on the fatigue fracture characteristics of Ti6Al4V was investigated. Two groups of specimens were separated due to different heat treatment conditions. Group one was stress-relief annealed at 650 ◦C, and group two was then treated with solid solution-aging. UNSM with the conditions of a static load of 25 N, vibration amplitude ...

In this paper, a fracto-metallographic analysis was performed on the cracked specimens of cold drawn pearlitic steel subjected to fatigue tests. Fatigue cracks are transcollonial and exhibit a preference for fracturing pearlitic lamellae, with non-uniform crack opening displacement values, micro-discontinuities, branchings, bifurcations and frequent local deflections that create microstructural...

This paper presents the results of channel cracking experiments performed on a multilayered structure. Room temperature creep behavior of a metallic underlayer was studied by using a newly developed channel cracking method. By the analysis of a channel crack propagating under tensile load in an elastic Si3N4 topical layer, the creep properties of an aluminum underlayer were determined. The expe...

Background One of the causative factors of root defects is the increased friction produced by rotary instrumentation. A high canal curvature may increase stress, making the tooth more susceptible to dentinal cracks. The purpose of this study was to evaluate dentinal micro-crack formation with the ProTaper NEXT and ProTaper Universal systems using LED transillumination, and to analyze the micro-...

A computational model of ultrasound scattering by micro-cracks in fiber reinforced polymer laminates is presented, foundational to study of micro-crack induced ultrasound attenuation. A model for transmission scattering response is developed using a boundary integral formulation, and associated approximate scattering theories are discussed. Numerical results are presented demonstrating applicat...

The life of a structure can be extended by early detection of cracks with appropriate repairs. In reality, structural failure is always accompanied by the formation of cracks and early detection of cracks is essential in extending structure life and preventing structural failure(1). Therefore, there is a huge amount of research on monitoring surface crack development in concrete structures, esp...

This study investigated the effects of the hot isostatic pressing process on the crack healing, microstructure, and mechanical properties of the laser repair-welded CM247LC precipitation-hardened superalloy. To ensure the strength of the repair-welded area, this study used the direct re-melting approach, and simulated the repair welding with the filler addition, which has a chemical composition...

The initiation and growth behavior of short fatigue cracks from the interfacial micro-notches in a SCS-6/Ti composite at various maximum applied stress levels were quantitatively characterized. Micro-notches in the interfacial reaction layer were induced by applying monotonic tensile loading prior to fatigue testing. The propagation and arrest behaviors of each individual crack were carefully m...

The crack self-healing behavior of high-performance steel-fiber reinforced cement composites (HPSFRCs) was investigated. High-strength deformed steel fibers were employed in a high strength mortar with very fine silica sand to decreasing the crack width by generating higher interfacial bond strength. The width of micro-cracks, strongly affected by the type of fiber and sand, clearly produced th...