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Cyclic Fatigue

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https://www.readbyqxmd.com/read/30343171/collagen-fibre-orientation-and-dispersion-govern-ultimate-tensile-strength-stiffness-and-the-fatigue-performance-of-bovine-pericardium
#1
A Whelan, J Duffy, R T Gaul, D O'Reilly, D R Nolan, P Gunning, C Lally, B P Murphy
The durability of bovine pericardium leaflets employed in bioprosthetic heart valves (BHVs) can significantly limit the longevity of heart valve prostheses. Collagen fibres are the dominant load bearing component of bovine pericardium, however fibre architecture within leaflet geometries is not explicitly controlled in the manufacture of commercial devices. Thus, the purpose of this study was to ascertain the influence of pre-determined collagen fibre orientation and dispersion on the mechanical performance of bovine pericardium...
September 26, 2018: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/30337752/-effect-of-autoclave-on-surface-microstructure-and-cyclic-fatigue-resistance-of-r-phase-rotary-instruments
#2
Y J Yang, B X Hou, X M Hou
OBJECTIVE: To compare the effects of autoclave on surface microstructure and cyclic fatigue resistance of K3XF and K3. METHODS: Forty-eight size 25, 0.06 taper 25 mm-long K3XF or K3 were randomly divided into 4 groups (n=12). The instruments from group 1 were not autoclaved, and the groups 2 to 4 underwent autoclave for 10 cycles, 20 cycles, and 30 cycles, respectively. The surface microstructure of two instruments randomly selected from each group was observed using scanning electron microscope (SEM)...
October 18, 2018: Beijing da Xue Xue Bao. Yi Xue Ban, Journal of Peking University. Health Sciences
https://www.readbyqxmd.com/read/30337751/-surface-microstructure-and-cyclic-fatigue-resistance-of-electro-discharged-machining-nickel-titanium-endodontic-instrument
#3
F F Wang, Y J Yang, X M Hou
OBJECTIVE: To compare the surface microstructures and cyclic fatigue resistance of HyFlex EDM with HyFlex CM and HyFlex NT. METHODS: Twelve 25 mm-long 25#/- HyFlex EDM and twelve 25 mm-long 25#/0.06 taper HyFlex CM or HyFlex NT were selected. The surface microstructure of the 2 instruments which were randomly selected from each group was observed by using scanning electron microscope (SEM). The remaining 10 instruments from each group were submitted to the cyclic fatigue test by using a simulated stainless steel root canal with 60° angle of curvature and curvature radius of 3...
October 18, 2018: Beijing da Xue Xue Bao. Yi Xue Ban, Journal of Peking University. Health Sciences
https://www.readbyqxmd.com/read/30314354/low-cycle-fatigue-behavior-of-steam-generator-tubes-under-axial-loading
#4
Xing He, Junfeng Chen, Wei Tian, Yuebing Li, Weiya Jin
Compared with the fatigue properties of the material (Inconel Alloy 690), the real fatigue lives of tubes are more meaningful in the fatigue design and assessment of steam generator (SG) tube bundles. However, it is almost impossible to get a satisfactory result by conducting fatigue tests on the tube directly. A tube with a uniform and thin wall easily fails near the clamping ends under cyclic loading due to the stress concentration. In this research, a set-up for fatigue tests of real tubes is proposed to overcome the stress concentration...
October 11, 2018: Materials
https://www.readbyqxmd.com/read/30305880/an-in-vitro-cyclic-fatigue-resistance-comparison-of-conventional-and-new-generation-nickel-titanium-rotary-files
#5
Celia Ruiz-Sánchez, Vicente Faus-Matoses, Teresa Alegre-Domingo, Ignacio Faus-Matoses, Vicente-José Faus-Llácer
Background: New designs and processing of Niquel-Titanium (NiTi) have been introduced to increase resistance to cyclic fatigue. The purpose of this study was to compare the cyclic fatigue resistance of 3 NiTi rotary instruments, ProTaper Next (PTN; Dentsply Maillefer, Ballaigues, Switzerland), Profile Vortex Blue (PVB; Dentsply Tulsa Dental, Tulsa, OK, USA) and ProTaper Universal (PTU; Dentsply Maillefer, Ballaigues, Switzerland). Material and Methods: A cyclic fatigue test was conducted operating instruments from ProTaper Next X2, Profile Vortex Blue 25...
August 2018: Journal of Clinical and Experimental Dentistry
https://www.readbyqxmd.com/read/30304838/application-of-differential-entropy-in-characterizing-the-deformation-inhomogeneity-and-life-prediction-of-low-cycle-fatigue-of-metals
#6
Mu-Hang Zhang, Xiao-Hong Shen, Lei He, Ke-Shi Zhang
The relation between deformation inhomogeneity and low-cycle-fatigue failure of T2 pure copper and the nickel-based superalloy GH4169 under symmetric tension-compression cyclic strain loading is investigated by using a polycrystal representative volume element (RVE) as the material model. The anisotropic behavior of grains and the strain fields are calculated by crystal plasticity, taking the Bauschinger effect into account to track the process of strain cycles of metals, and the Shannon's differential entropies of both distributions of the strain in the loading direction and the first principal strain are employed at the tension peak of the cycles as measuring parameters of strain inhomogeneity...
October 9, 2018: Materials
https://www.readbyqxmd.com/read/30282946/fatigue-performance-of-rc-beams-strengthened-with-cfrp-under-overloads-with-a-ladder-spectrum
#7
Zhan-Biao Chen, Pei-Yan Huang, Zheng-Wei Li, Xin-Yan Guo, Chen Zhao, Xiao-Hong Zheng, Yi Yang
Vehicle overload is detrimental to bridges and traffic safety. This paper presents a study on the fatigue performance of typical reinforced concrete (RC) beams of highway bridges under vehicle overload. A definition method of vehicle overload and a construction method of overload ladder spectrum were first proposed based on traffic data acquisition, statistical analysis and structural calculation of the highway bridges in Guangzhou. A fatigue experimental method was also proposed with the three-ladder vehicle overload spectrum, and the fatigue tests of 15 RC beams strengthened with carbon fiber reinforced polymer (CFRP) under three loading levels were then carried out...
October 3, 2018: Sensors
https://www.readbyqxmd.com/read/30274032/durability-of-self-healing-dental-composites-a-comparison-of-performance-under-monotonic-and-cyclic-loading
#8
Mobin Yahyazadehfar, George Huyang, Xiaohong Wang, Yuwei Fan, Dwayne Arola, Jirun Sun
Durability is an important quality of dental restorative materials, and the ability to autonomously heal damage incurred during their oral function is highly desirable. OBJECTIVE: The objective was to evaluate the improvement in durability of self-healing dental composites (SHDCs) in terms of their resistance to fracture and capacity for healing of damage under monotonic and cyclic loading. METHODS: SHDCs were prepared by incorporating dental resin composites with microcapsules containing healing liquid...
December 1, 2018: Materials Science & Engineering. C, Materials for Biological Applications
https://www.readbyqxmd.com/read/30267276/mechanical-and-hydrolytic-degradation-of-an-ormocer%C3%A2-based-bis-gma-free-resin-composite
#9
Elena Klauer, Renan Belli, Anselm Petschelt, Ulrich Lohbauer
OBJECTIVES: The aim of the study was to evaluate the mechanical stability of bisphenol A-glycidyl methacrylate (Bis-GMA) and Ormocer-based resin composites before and after water absorption and to examine water saturation. MATERIAL AND METHODS: Disc-shaped specimens of the Bis-GMA (Grandio SO, Voco) and the Ormocer-based (Admira Fusion, Voco) dental resin composites were produced, stored in water, and weighed after pre-determined times to measure the absorbed water...
September 28, 2018: Clinical Oral Investigations
https://www.readbyqxmd.com/read/30257433/investigation-of-fatigue-behavior-of-abs-and-pc-abs-polymers-at-different-temperatures
#10
Andrea Mura, Alessando Ricci, Giancarlo Canavese
Plastics are widely used in structural components where cyclic loads may cause fatigue failure. In particular, in some applications such as in vehicles, the working temperature may change and therefore the strength of the polymeric materials. In this work, the fatigue behavior of two thermoplastic materials (ABS and PC-ABS) at different temperatures has been investigated. In particular, three temperatures have been considered representing the working condition at room temperature, at low temperature (winter conditions), and high temperature (summer conditions and/or components close to the engine)...
September 25, 2018: Materials
https://www.readbyqxmd.com/read/30255216/in-vitro-comparison-of-cyclic-fatigue-resistance-of-two-rotary-single-file-endodontic-systems-onecurve-versus-oneshape
#11
Marco Serafin, Matteo De Biasi, Vittorio Franco, Daniele Angerame
The aim of the present study was to evaluate the difference in cyclic fatigue resistance between OneCurve (OC) and OneShape (OS) endodontic single-file NiTi systems in a severely curved artificial canal. After sample size calculation (α = 0.01; β = 0.20; σ = 20.0; δ = 20.0), 25 OC and 25 OS files were used. An artificial canal with 60° angle and 5-mm radius of curvature was milled in a stainless-steel block reproducing the size and taper of the files used. The test device was electrically heated to maintain the environmental temperature at 37 °C...
September 25, 2018: Odontology
https://www.readbyqxmd.com/read/30244383/cyclic-fatigue-of-reciproc-blue-and-reciproc-instruments-exposed-to-intracanal-temperature-in-simulated-severe-apical-curvature
#12
Uğur Inan, Cangül Keskin, Özlem Sivas Yilmaz, Gözde Baş
OBJECTIVE: The aim of this study was to evaluate the cyclic fatigue resistance of Reciproc and Reciproc Blue by testing in a severe apical curvature at intracanal temperature. MATERIALS AND METHODS: Eighteen Reciproc R25 (25.08) and Reciproc Blue (25.08) instruments were tested in a cyclic fatigue device at body temperature (37 °C) using a stainless steel block with an artificial canal with a curvature angle of 90° and radius of curvature of 2 mm. The number of cycles to fracture (NCF) was calculated...
September 22, 2018: Clinical Oral Investigations
https://www.readbyqxmd.com/read/30242860/mechanical-analysis-of-suture-attachment-methods-in-toggle-suture-constructs
#13
Kathleen A Kraska, Joshua Jackson
OBJECTIVE: To determine the effect of the method used to attach OrthoFiber #5 to a 1/8-in Securos toggle rod on the mechanical properties of the resulting construct. STUDY DESIGN: Prospective bench top mechanical analysis. SAMPLE POPULATION: One hundred twenty-eight OrthoFiber #5-toggle rod suture constructs. METHODS: Toggle-suture constructs (groups A-H) were prepared by using 8 methods to attach OrthoFiber #5 to a 1/8-in toggle rod (n = 16 constructs/group)...
September 21, 2018: Veterinary Surgery: VS
https://www.readbyqxmd.com/read/30225062/an-experimental-study-of-deformation-and-fracture-characteristics-of-shale-with-pore-water-pressure-and-under-triaxial-cyclic-loading
#14
Changbao Jiang, Tianyu Lu, Dongming Zhang, Guangzhi Li, Minke Duan, Yufei Chen, Chaosheng Liu
The deformation and fracture characteristics of shale in the Changning-Xingwen region were experimentally studied under triaxial cyclic loading with a controlled pore-water pressure. An RLW-2000M microcomputer-controlled coal-rock rheometer was used in the State key Laboratory of coal mine disaster dynamics and control in Chongqing University. These experimental results have indicated the following. (i) The shale softened after being saturated with water, while its failure strength decreased with the increase of axial strain...
August 2018: Royal Society Open Science
https://www.readbyqxmd.com/read/30224178/the-use-of-suture-tape-and-suture-wire-in-arthroscopic-rotator-cuff-repair-a-comparative-biomechanics-study
#15
Lachlan Huntington, Jasamine Coles-Black, Martin Richardson, Tony Sobol, Jonathon Caldow, Jason Chuen, David C Ackland
BACKGROUND: Rotator cuff repair surgery aims to create a secure, pressurized tendon-bone footprint to permit re-establishment of the fibrovascular interface and tendon healing. Flat-braided suture-tape is an alternative suture material to traditional suture-wire that has potential to reproduce a larger repair construct contact area. The objective of this study was to compare contact pressure, area as well as the mechanical fatigue strength between suture-wire and suture-tape Suture-bridge repair constructs in an ovine model...
September 6, 2018: Injury
https://www.readbyqxmd.com/read/30223213/precision-of-different-fatigue-methods-for-predicting-glass-ceramic-failure
#16
Rodrigo Ottoni, Jason A Griggs, Pedro H Corazza, Álvaro Della Bona, Márcia Borba
This study aimed to characterize the fatigue behavior using two fatigue methods, boundary and staircase, and to predict the probability of failure (Pf ) of zirconia-reinforced lithium silicate glass-ceramic (ZLS). Bar-shaped specimens of ZLS (18 ×4 ×1.2 mm) were fabricated. Thirty specimens were subjected to a three-point flexural strength test using a universal testing machine with 0.5 mm/min crosshead speed, in 37 °C distilled water. Flexural strength data were analyzed with Weibull statistics...
September 5, 2018: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/30220505/effect-of-loading-frequency-on-cyclic-fatigue-lifetime-of-a-standard-diameter-implant-with-an-internal-abutment-connection
#17
Yuanyuan Duan, Jason A Griggs
OBJECTIVE: To investigate the effect of loading frequency on the fatigue lifetime of one standard-diameter titanium dental implant system. METHODS: Thirty-six titanium dental implant specimens (Bone Level RC, Straumann) were assembled following manufacturer's instructions and torqued into cylindrical holder blocks following the apparatus specified by the ISO 14801 test standard. Stainless steel loading hemispheres were bonded on the abutments with a moment arm of 11mm...
September 13, 2018: Dental Materials: Official Publication of the Academy of Dental Materials
https://www.readbyqxmd.com/read/30210371/emotion-transfer-emotion-regulation-and-empathy-related-processes-in-physician-patient-interactions-and-their-association-with-physician-well-being-a-theoretical-model
#18
Sonja Weilenmann, Ulrich Schnyder, Brian Parkinson, Claudio Corda, Roland von Känel, Monique C Pfaltz
Physicians experience many emotionally challenging situations in their professional lives, influencing their emotional state through emotion contagion or social appraisal processes. Successful emotion regulation is crucial to sustain health, enable well-being, foster resilience, and prevent burnout or compassion fatigue. Despite the alarmingly high rate of stress-related disorders in physicians, affecting not only physician well-being, but also outcomes such as physician performance, quality of care, or patient satisfaction, research on how to deal with emotionally challenging situations in physicians is lacking...
2018: Frontiers in Psychiatry
https://www.readbyqxmd.com/read/30209682/effects-of-etidronate-naocl-edta-irrigation-solutions-and-their-combinations-on-cyclic-fatigue-resistance-of-nickel-titanium-single-file-rotary-and-reciprocating-instruments-at-body-temperature
#19
Cevat Emre Erik, Taha Özyürek
The aim of the present study was to compare the effect of etidronic acid (HEBP), NaOCl, and EDTA solutions and their combinations on cyclic fatigue resistance of NiTi RPC Blue (RPC Blue), HyFlex EDM (HEDM), and WaveOne Gold (WOG) instruments having different metallurgic characteristics at the body temperature (37 °C). 100 WOG, 100 RPC Blue, and 100 HEDM NiTi files were randomly divided into 5 groups and immersed in the following solutions: group 1, distilled water; group 2, 6% NaOCl; group 3, 17% EDTA; group 4, 18% HEBP; group 5, 6% NaOCl and 18% HEBP...
September 12, 2018: Odontology
https://www.readbyqxmd.com/read/30196186/fatigue-behavior-and-surface-characterization-of-a-y-tzp-after-laboratory-grinding-and-regeneration-firing
#20
Gabriela Scatimburgo Polli, Gabriel Rodrigues Hatanaka, Filipe de Oliveira Abi-Rached, Márcio de Sousa Góes, José Mauricio Dos Santos Nunes Reis
This study evaluated the effect of grinding and regeneration firing on the flexural fatigue limit and surface characterization of Lava™ Y-TZP ceramic. Forty bar-shaped specimens with 20 × 4.0 × 1.2 mm constituted the as-sintered group (AS = control group), and 80 specimens with 20 × 4.0 × 1.5 mm were ground with cylindrical laboratory stone under water-cooling (WG) or in a dry condition (G) to reach 1.2 mm in thickness. Half of specimens were submitted to regeneration firing (1000 °C, 30 min), forming the groups AS/R, WG/R and G/R...
August 23, 2018: Journal of the Mechanical Behavior of Biomedical Materials
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