Influence of short-term cooling on the performance of superelastic and thermally-treated rotary NiTi files tested in dynamic cyclic fatigue model

The better understanding of the clinically important behavioral features of new instrument systems has an important significance for the clinical endodontics. This study aimed to investigate the shaping and centering ability as well as cyclic fatigue resistance of HyFlex CM (CM), HyFlex EDM (EDM) and EdgeFile (EF) thermally treated nickel–titanium (NiTi) endodontic instrument systems. Sixty curved root canals of the mesial roots of mandibular molars were randomly assigned into three groups (n = 20) and shaped using CM, EDM and EF files up to the size 40 and taper 04 of the instruments. µCT scanning of the specimens before and after preparation was performed and the morphometric 2D and 3D parameters were evaluated in the apical, middle and coronal thirds of root canals. In each group, 40.04 instruments (n = 20) were subjected to the cyclic fatigue resistance test in artificial root canals at 37 °C temperature until fractures occurred, and the number of cycles to failure (NCF) was calculated. The fractographic analysis was performed using a scanning electron microscope, evaluating topographic features and surface profiles of the separated instruments. The one-way analysis of variance with post hoc Tuckey’s test was used for statistical analysis of the data; the significance level was set at 5%. All systems prepared the comparable percentage of root canal surface with the similar magnitude of canal transportation in all root thirds (p > 0.05), but demonstrated significantly different resistance to cyclic fatigue (p < 0.05). The most resistant to fracture was EF, followed by EDM and CM. The length of the fractured fragments was not significantly different between the groups, and fractographic analysis by SEM detected the typical topographic features of separated thermally treated NiTi instrument surfaces.

Download Full-text

NEMO Type Acrylic Plastic Spherical Hull for Manned Operation to 3000 ft Depth

Journal of Engineering for Industry ◽

10.1115/1.3438934 ◽

1976 ◽

Vol 98 (2) ◽

pp. 537-549 ◽

Cited By ~ 2

Author(s):

J. D. Stachiw

Keyword(s):

Fatigue Life ◽

Stress Wave ◽

Cyclic Fatigue ◽

Short Term ◽

Destructive Testing ◽

Pressure Cycling ◽

Acrylic Plastic ◽

Scale Models ◽

Spherical Pressure

NEMO Mod 2000 acrylic plastic pressure hull assembly represents the latest addition to the NEMO hull series represented by NEMO Mod 600 and 1000 hull assemblies. The 66 in. OD × 58 in. ID spherical acrylic hull with aluminum hatches has successfully withstood 24 hr long external hydrostatic pressurizations to 450, 900, 1350, and 1800 psi. Pressure cycling and short term destructive testing of 15 in. OD × 13 in. ID scale models has shown that the crackfree fatigue life is in excess of 1000 pressure cycles to 1500 psi and the short term implosion pressure is in the range of 4750–5000 psi. Stress wave emissions have been found to be a good indicator of incipient failure. NEMO Mod 2000 spherical pressure hulls with panoramic visibility are considered to be acceptable for manned submersibles with 3000 ft operational depth capability. The cyclic fatigue life of such hulls is conservatively predicted to be at least 12 × 106 ft hr.

Download Full-text

Extension of recovery time from fatigue by repeated rest with short-term sleep during continuous fatigue load: Development of chronic fatigue model

Journal of Neuroscience Research ◽

10.1002/jnr.23718 ◽

2016 ◽

Vol 94 (5) ◽

pp. 424-429 ◽

Cited By ~ 3

Author(s):

Akinori Kanzaki ◽

Takashi Okauchi ◽

Di Hu ◽

Tomotaka Shingaki ◽

Yumiko Katayama ◽

...

Keyword(s):

Recovery Time ◽

Chronic Fatigue ◽

Fatigue Load ◽

Short Term ◽

Fatigue Model

Download Full-text

Effect of Extended Aging on Asphalt Materials Containing Re-Refined Engine Oil Bottoms

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/2632-07 ◽

2017 ◽

Vol 2632 (1) ◽

pp. 60-69 ◽

Cited By ~ 11

Author(s):

David J. Mensching ◽

Adrian Andriescu ◽

Christopher DeCarlo ◽

Xinjun Li ◽

Jack S. Youtcheff

Keyword(s):

Low Temperature ◽

Fatigue Testing ◽

Asphalt Mixture ◽

Field Performance ◽

Cyclic Fatigue ◽

Engine Oil ◽

Short Term ◽

Bending Beam Rheometer ◽

The Difference

The use of re-refined engine oil bottoms (REOBs) in asphalt pavements is a topic of much debate because the aging susceptibility and quantity of the additive in the binder may affect field performance. In this study, four mixtures with varying REOB contents (up to 15%) were long-term oven aged by using a high-temperature, short-duration method (135°C, 24 h) and compared with existing data on mixtures aged with more conventional short-term and long-term oven-aging procedures. The recovered binders underwent Superpave® grading, double-edge notched tension, and extended bending beam rheometer testing, and the binders were subjected to dynamic modulus, cyclic fatigue testing in the asphalt mixture performance tester, and thermal stress restrained specimen testing. Results showed a general insensitivity when short-term oven-aged (135°C, 4 h) materials were compared with long-term oven-aged (85°C, 5 days) materials, whereas the aging process at 135°C over 24 h resulted in substantial changes to the stiffness and relaxation properties across high-, intermediate-, and low-temperature modes. The difference between the stiffness-based and slope-based low-temperature performance grades appears to be an indicator for REOB modification, with the test for physical hardening of the binder being more sensitive than standard bending beam rheometer testing. The details in this paper provide information for the asphalt pavement community to consider as specifications. Standard practices are developed to address REOB modification.

Download Full-text

Reciproc blue: the new generation of reciprocation

Giornale Italiano di Endodonzia ◽

10.4081/j.gien.2017.26 ◽

2017 ◽

Vol 31 (2) ◽

pp. 96-101

Author(s):

Ghassan Yared

Keyword(s):

Clinical Research ◽

Cyclic Fatigue ◽

Clinical Applications ◽

Preparation Procedure ◽

Glide Path ◽

New Generation ◽

Thermally Treated

Aim: This article introduces the Reciproc1 blue system and describes the clinical technique with and without creating a glide path. Methodology: The concept of canal preparation with only one mechanical instrument used in reciprocation was introduced several years ago. Studies and clinical research have shown the efficiency and the safety of the Reciproc1 instrument in the preparation of the majority of canals without creating a glide path, and in the retreatment procedure. Results: Reciproc1 blue, a thermally treated instrument is an improved version of the original Reciproc1 instrument; it has an increased resistance to cyclic fatigue and a greater flexibility enabling a safer and smoother canal preparation procedure, and a wider range of clinical applications. Conclusions: This article introduces and describes the clinical technique with which the Reciproc1 blue instrument is used, even without the need to create a glide path with manual files before using the mechanical instrument.

Download Full-text

Cyclic fatigue using severely curved canals and torsional resistance of thermally treated reciprocating instruments

Clinical Oral Investigations ◽

10.1007/s00784-018-2362-9 ◽

2018 ◽

Vol 22 (7) ◽

pp. 2633-2638 ◽

Cited By ~ 15

Author(s):

Emmanuel João Nogueira Leal Silva ◽

Victor Talarico Leal Vieira ◽

Fernanda Hecksher ◽

Marja Ribeiro Silva dos Santos Oliveira ◽

Henrique dos Santos Antunes ◽

...

Keyword(s):

Cyclic Fatigue ◽

Torsional Resistance ◽

Reciprocating Instruments ◽

Thermally Treated

Download Full-text

Effect of short-term treatment with alendronate on ulnar bone adaptation to cyclic fatigue loading in rats

Journal of Orthopaedic Research® ◽

10.1002/jor.20395 ◽

2007 ◽

Vol 25 (8) ◽

pp. 1070-1077 ◽

Cited By ~ 24

Author(s):

Jennifer G. Barrett ◽

Susannah J. Sample ◽

Jenna McCarthy ◽

Vicki L. Kalscheur ◽

Peter Muir ◽

...

Keyword(s):

Fatigue Loading ◽

Cyclic Fatigue ◽

Term Treatment ◽

Bone Adaptation ◽

Short Term ◽

Short Term Treatment

Download Full-text

Flanged Acrylic Plastic Hemispherical Shells for Undersea Systems—Part 2: Static and Cyclic Fatigue Life Under Hydrostatic Loading

Journal of Engineering for Industry ◽

10.1115/1.3439417 ◽

1978 ◽

Vol 100 (2) ◽

pp. 249-260

Author(s):

J. D. Stachiw ◽

R. Sletten

Keyword(s):

Fatigue Life ◽

Fatigue Cracks ◽

Cyclic Fatigue ◽

Bearing Surface ◽

Short Term ◽

Ring Groove ◽

Working Pressure ◽

Temperature Range ◽

Acrylic Plastic ◽

Hydrostatic Loading

Over 25 acrylic plastic windows with t/Ri = 0.364 in the shape of hemispherical domes with equatorial flanges have been thermoformed from flat sheets and tested under short term, long term, and cyclic pressure loading at 65–75°F ambient temperature. Two kinds of flanges with O-ring grooves on the bearing surfaces were experimented with: Type 1, a flat lip with a rounded heel and instep, and Type II, a conical lip with a rounded heel. The 14,500 psi short term critical pressure of hemispherical windows with t/Ri = 0.364 was found to be independent of the equatorial flange configuration. Both the static and cyclic fatigue lives of the windows were also found to be independent of equatorial flange configuration. In either case, the maximum acceptable working pressure for 65–75°F temperature range was found to be 1000 psi. Only by elimination of the O-ring groove in the bearing surface of the window flange and the use of a thin neoprene bearing gasket between the arylic flange and the steel is it possible to extend the working pressure to 2000 psi for 65–75°F temperature range. Operating the flanged windows at pressures in excess of the safe working pressures shown above will generate fatigue cracks in the bearing surface of the flange in less than 1000 pressure cycles; at 5000 psi pressure the cyclic fatigue life decreases to less than 100 cycles.

Download Full-text

Cyclic fatigue and torsional strength of three different thermally treated reciprocating nickel-titanium instruments

Clinical Oral Investigations ◽

10.1007/s00784-017-2295-8 ◽

2017 ◽

Vol 22 (4) ◽

pp. 1865-1871 ◽

Cited By ~ 22

Author(s):

Murilo Priori Alcalde ◽

Marco Antonio Hungaro Duarte ◽

Clovis Monteiro Bramante ◽

Bruno Carvalho de Vasconselos ◽

Mario Tanomaru-Filho ◽

...

Keyword(s):

Cyclic Fatigue ◽

Nickel Titanium ◽

Torsional Strength ◽

Thermally Treated

Download Full-text

Spherical Sector Windows With Restrained Edge for Undersea Applications

Journal of Engineering for Industry ◽

10.1115/1.3439260 ◽

1977 ◽

Vol 99 (2) ◽

pp. 459-468

Author(s):

J. D. Stachiw

Keyword(s):

Spherical Shell ◽

Experimental Evaluation ◽

Cyclic Fatigue ◽

Bearing Surface ◽

Short Term ◽

Cyclic Pressure ◽

Fatigue Data ◽

Vertical Bearing ◽

Radial Thrust

A new concept for the mounting of spherical sector windows has been experimentally evaluated under short-term, long-term, and cyclic pressure loadings. The new mounting concept requires that the spherical sector windows be provided with square edges instead of conical edges. The horizontal bearing surface of the square edge carries the axial and the vertical bearing surface the radial thrust of the spherical sector window. Experimental evaluation of the new mounting concept has shown that the spherical windows with square edges are subjected to larger flexure moments than similar windows with conical edges. However, the short-term critical pressures of spherical sector windows with square edges and included angle 75 deg < α < 180 deg were found to be only 10 percent less than those of similar windows with conical edges. For spherical sectors with α < 75 deg the square edge mounting provides significantly higher short-term implosion pressures than conical edge mountings. Based on the short-term critical pressures, strains, stresses, and cyclic fatigue data generated by this study, the spherical shell sector windows with square edge mounting are considered acceptable for service in manned submersibles, habitats, or diving bells.

Download Full-text