scholarly journals Fatigue Strength as a Function of Preloading in Dynamic Fatigue Testing of Glass and Ceramics

1996 ◽  
Author(s):  
Sung R. Choi ◽  
Jonathan A. Salem ◽  
John P. Gyekenyesi
Keyword(s):  
Fatigue Strength ◽  
Failure Time ◽  
Fatigue Testing ◽  
Slow Crack Growth ◽  
Fatigue Loading ◽  
Soda Lime ◽  
Ceramic Materials ◽  
Soda Lime Glass ◽  
Testing Time ◽  
Dynamic Fatigue

The solution of fatigue strength as a function of preloading in dynamic fatigue testing was obtained analytically and numerically. The effect of preloading on dynamic fatigue strength decreases with increasing fatigue parameter (n), and for n ≥ 20 the effect is negligible up to a preloading of 90 %. The solution was verified by dynamic fatigue experiments conducted with soda-lime glass and alumina specimens in room-temperature distilled water. This result showed that one can apply a preloading corresponding up to 90 % of fatigue strength for most glass and ceramic materials, resulting in a dramatic saving of testing time in dynamic fatigue testing. The key feature that makes this technique feasible is that most of the slow crack growth under dynamic fatigue loading occurs close to failure time where a dynamic fatigue strength is defined.

Fatigue Strength as a Function of Preloading in Dynamic Fatigue Testing of Glass and Ceramics

1997 ◽  
Vol 119 (3) ◽  
pp. 493-499 ◽  
Author(s):  
S. R. Choi ◽  
J. P. Gyekenyesi
Keyword(s):  
Fatigue Strength ◽  
Failure Time ◽  
Fatigue Testing ◽  
Slow Crack Growth ◽  
Fatigue Loading ◽  
Soda Lime ◽  
Ceramic Materials ◽  
Soda Lime Glass ◽  
Testing Time ◽  
Dynamic Fatigue

The solution of fatigue strength as a function of preloading in dynamic fatigue (constant stress-rate) testing was obtained analytically and numerically. The effect of preloading on dynamic fatigue strength decreases with increasing fatigue parameter (n), and for n ≥ 20 the effect is negligible up to a preloading of 90 percent. The solution was verified by dynamic fatigue experiments conducted with soda-lime glass and alumina specimens in room-temperature distilled water. This result showed that one can apply a preloading corresponding up to 90 percent of fatigue strength for most glass and ceramic materials, resulting in a dramatic saving of testing time in dynamic fatigue testing. The key feature that makes this technique feasible is that most of the slow crack growth under dynamic fatigue loading occurs close to failure time where the dynamic fatigue strength is defined.

Dynamic Fatigue Testing of Candidate Ceramic Materials for Turbine Engines to Determine Slow-Crack-Growth Parameters

1997 ◽  
Vol 119 (2) ◽  
pp. 273-278 ◽  
Author(s):  
N. R. Osborne ◽  
G. A. Graves ◽  
M. K. Ferber
Keyword(s):  
High Temperature ◽  
Crack Growth ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Growth Parameters ◽  
Slow Crack Growth ◽  
Growth Parameter ◽  
Ceramic Materials ◽  
Material Strength ◽  
Dynamic Fatigue

The purpose of this study was to evaluate the mechanical strength and slow-crack-growth parameter values for two commercially available silicon nitrides, SN-88 and NT164, at three high-temperature conditions. Weibull analysis and dynamic fatigue slow-crack-growth parameters were used to characterize the material strength and resistance to slow crack growth at high temperatures for use in life prediction models. Although both materials are commercially available Si3N4, their high-temperature behavior was found to be significantly different.

Dynamic Fatigue Testing of Candidate Ceramic Materials for Turbine Engines to Determine Slow-Crack-Growth Parameters

1995 ◽  
Author(s):  
Nora R. Osborne ◽  
George A. Graves ◽  
Matt K. Ferber
Keyword(s):  
High Temperature ◽  
Crack Growth ◽  
Prediction Models ◽  
Fatigue Testing ◽  
Growth Parameters ◽  
Slow Crack Growth ◽  
Growth Parameter ◽  
Ceramic Materials ◽  
Material Strength ◽  
Dynamic Fatigue

The purpose of this study was to evaluate the mechanical strength and slow-crack-growth parameter values for two commercially available silicon nitrides, SN-88 and NT164, at three high temperature conditions. Weibull analysis and dynamic fatigue slow-crack-growth parameters were used to characterize the material strength and resistance to slow crack growth at high temperatures for use in life prediction models. Although both materials are commercially available Si3N4, their high temperature behavior was found to be significantly different.

Influence of the Type of Dispersant on the Properties of Casting Slips of Porcelains with Soda-Lime Glass

2006 ◽  
Vol 530-531 ◽  
pp. 449-455
Author(s):  
S.R. Bragança ◽  
R. Camaratta ◽  
A.C. Taborda ◽  
C.P. Bergmann
Keyword(s):  
Slip Casting ◽  
Soda Lime ◽  
Ceramic Materials ◽  
Partial Substitution ◽  
Attractive Alternative ◽  
Soda Lime Glass ◽  
Glass Waste ◽  
Different Types ◽  
Casting Slip ◽  
Extruded Products

The use of glass residues for the reduction of firing temperature of ceramic materials products has become an attractive alternative. For pressed or extruded products, such as tiles and bricks, the use of glass is sufficiently simple, since only milling and mixing to the industrial mass batch in partial substitution of conventional fluxes are necessary. However, in slip casting products, such as china and porcelains, the glass presence destabilizes the casting slip. This is the motivation of this work. Different types of dispersants and their influence on the properties of slips containing glass waste were evaluated. The experimental results showed that the use of conventional dispersant (sodium silicate) is not adequate. The stabilization of slips was possible only with organic dispersants. Therefore, the factors that determine the success or failure of dispersants were also analyzed.

Evaluation of Total Ankle Arthroplasty Using Highly Crosslinked Ultrahigh-Molecular-Weight Polyethylene Subjected to Physiological Loading

2019 ◽  
Vol 40 (8) ◽  
pp. 880-887 ◽  
Author(s):  
Jeffrey E. Bischoff ◽  
Mehul A. Dharia ◽  
Justin S. Hertzler ◽  
Oliver N. Schipper
Keyword(s):  
Fatigue Strength ◽  
Fatigue Testing ◽  
Ultrahigh Molecular Weight Polyethylene ◽  
Fatigue Loading ◽  
Strength Properties ◽  
Total Ankle Arthroplasty ◽  
Wear Properties ◽  
Ankle Arthroplasty ◽  
Walking Gait

Background: Highly crosslinked polyethylene (HXLPE) was developed for its superior wear properties in comparison to conventional polyethylene (CPE). Concern over fatigue resistance has prevented widespread adoption of HXLPE for use in total ankle arthroplasty (TAA). The aim of this study was to determine whether HXLPE has sufficient fatigue strength for total ankle arthroplasty under simulated physiologically relevant motion profiles and loading in the ankle. Methods: Physiologic load and motion profiles representative of walking gait were incorporated into a computational model of a semiconstrained, fixed-bearing TAA to determine the loading state with highest stresses in the HXLPE bearing. Subsequent fatigue testing to 10 million cycles (Mc) at 5600 N was performed to assess bearing strength. Results: Peak stresses in the bearing were predicted at peak axial load and peak dorsiflexion during gait, occurring near heel off. All samples withstood 10 Mc of fatigue loading at that orientation without polyethylene bearing fracture. Conclusion: HXLPE had sufficient fatigue strength to withstand 10 Mc of loading at more than 5 times body weight at the point of peak stresses during simulated gait in total ankle arthroplasty. Clinical Relevance: HXLPE may be mechanically strong enough to withstand the in vivo demands of the ankle. Improvements in wear afforded by HXLPE can be obtained without compromising sufficient polyethylene strength properties in total ankle arthroplasty.

scholarly journals Rescue Augmentation: Increased Stability in Augmentation After Initial Loosening of Pedicle Screws

2020 ◽  
pp. 219256822091912
Author(s):  
Lukas Weiser ◽  
Gerd Huber ◽  
Kay Sellenschloh ◽  
Klaus Püschel ◽  
Michael M. Morlock ◽  
...  
Keyword(s):  
Fatigue Strength ◽  
Bone Density ◽  
Fatigue Testing ◽  
Quantitative Computed Tomography ◽  
Pedicle Screws ◽  
Fatigue Loading ◽  
Cement Augmentation ◽  
Fatigue Load ◽  
The Impact

Study Design: Biomechanical study. Objectives: Failure of pedicle screws is a major problem in spinal surgery not only postoperatively, but also intraoperatively. The aim of this study was to evaluate whether cement augmentation may restore mounting of initially loosened pedicle screws. Methods: A total of 14 osteoporotic or osteopenic human cadaveric vertebral bodies (L2)—according to quantitative computed tomography (QCT)—were instrumented on both sides by conventional pedicle screws and cement augmented on 1 side. In vitro fatigue loading (cranial-caudal sinusoidal, 0.5 Hz) with increasing peak force (100 N + 0.1 N/cycles) was applied until a screw head displacement of 5.4 mm (∼20°) was reached. After loosening, the nonaugmented screw was rescue augmented, and fatigue testing was repeated. Results: The fatigue load reached 207.3 N for the nonaugmented screws and was significantly ( P = .009) exceeded because of initial cement augmentation (300.6 N). The rescue augmentation after screw loosening showed a fatigue load of 370.1 N which was significantly higher ( P < .001) compared with the nonaugmented screws. The impact of bone density on fatigue strength decreased from the nonaugmented to the augmented to the rescue-augmented screws and shows the greatest effect of cement augmentation on fatigue strength at low bone density. Conclusions: Rescue augmentation leads to similar or higher fatigue strengths compared with those of the initially augmented screws. Therefore, the cement augmentation of initially loosened pedicle screws is a promising option to restore adequate screw stability.

Sign in / Sign up

Export Citation Format

Share Document