E-9 EFFECT OF RESIDUAL STRESS ON SLOW CRACK GROWTH AND STATIC FATIGUE BEHAVIORS IN THERMALLY TEMPERED GLASS(Session: Fatique/SCG)

Author(s):  
Hitoo Tokunaga ◽  
Kiyohiko Ikeda ◽  
Gang Deng ◽  
Hiroyuki Kinoshita ◽  
Koichi kaizu
2019 ◽  
Vol 3 (3) ◽  
pp. 78
Author(s):  
Jacques Lamon ◽  
Mohamed R’Mili

The present paper discusses the statistical features of static fatigue for E-glass multifilament tows in water. In such an aggressive environment, the glass fibres are sensitive to slow crack propagation from micron-sized flaws. Rupture and interrupted static fatigue tests under constant deformation in water, as well as tensile tests in inert environments on tows after fatigue were carried out on E-glass fibre tows that comprised around 2000 single filaments. The slow crack growth constants and the fast fracture statistical parameters for filaments were extracted from the outcome of experiments on tows, i.e., the load relaxation curves during fatigue and stress-strain curves during the tensile tests. These parameters provide a pertinent data base for the prediction of several characteristics in various conditions of fatigue for filaments and tows including statistical distributions of lifetimes and residual strengths, strength degradation during fatigue, size effects on lifetime and tow residual behaviour. Equations for calculation of filament lifetime and residual strength, and tow tensile behaviour were based on the model of slow crack growth and Weibull statistical distribution. Calculations using strength-probability-time relations provided insight into static fatigue behaviour of tows in water. Validity of the approach was assessed by the comparison of experimental and predicted tow residual behaviours.


Author(s):  
Sung R. Choi ◽  
D. Calvin Faucett ◽  
Brenna Skelley

An extensive experimental work for Pyroceram™ 9606 glass-ceramic was conducted to determine static fatigue at ambient temperature in distilled water. This work was an extension and companion of the previous work conducted in dynamic fatigue. Four different applied stresses ranging from 120 to 170 MPa was incorporated with a total of 20–23 test specimens used at each of four applied stresses. The slow crack growth parameters n and D were found to be n = 19 and D = 45 with a coefficient of correlation of rcoef = 0.9653. The Weibull modulus of time to failure was in a range of msf = 1.6 to 1.9 with an average of msf = 1.7±0.2. A life prediction using the previously-determined dynamic fatigue data was in excellent agreement with the static fatigue data. The life prediction approach was also applied to advanced monolithic ceramics and ceramic matrix composites based on their dynamic and static fatigue data determined at elevated temperatures. All of these results indicated that a SCG mechanism governed by a power-law crack-growth formulation was operative, a commonality of slow crack growth in these materials systems.


Author(s):  
Sung R. Choi ◽  
D. Calvin Faucett ◽  
Brenna Skelley

An extensive experimental work for Pyroceram™ 9606 glass–ceramic was conducted to determine static fatigue at ambient temperature in distilled water. This work was an extension and companion of the previous work conducted in dynamic fatigue. Four different applied stresses ranging from 120 to 170 MPa was incorporated with a total of 20–23 test specimens used at each of four applied stresses. The slow crack growth (SCG) parameters n and D were found to be n = 19 and D = 45 with a coefficient of correlation of rcoef = 0.9653. The Weibull modulus of time to failure was in a range of msf = 1.6–1.9 with an average of msf = 1.7 ± 0.2. A life prediction using the previously determined dynamic fatigue data was in excellent agreement with the static fatigue data. The life prediction approach was also applied to advanced monolithic ceramics and ceramic matrix composites (CMCs) based on their dynamic and static fatigue data determined at elevated temperatures. All of these results indicated that a SCG mechanism governed by a power-law crack growth formulation was operative, a commonality of SCG in these materials systems.


2019 ◽  
Vol 827 ◽  
pp. 141-146
Author(s):  
Jan Poduška ◽  
Pavel Hutař ◽  
Andreas Frank ◽  
Gerald Pinter ◽  
Luboš Náhlík

Outstanding durability of plastic pressure and non-pressure pipes can cause difficulties, when a reasonable lifetime estimation is needed. It is impossible to prove the lifetime by testing, but there is a method of calculation that can provide a certain idea about the expected lifetime. The lifetime estimation is based on the assumption that the failure occurs as a result of the slow crack growth mechanism and it is calculated using the linear elastic fracture mechanics approach. Numerical simulations of crack growth in the pipe are necessary for this calculation. These simulations must consider various effects that can play a role in the lifetime. This paper deals with the lifetime calculations of a pressure and a non-pressure corrugated pipe considering the soil loads acting on pipes when they are buried. In the simulation of the pressure pipe, a combination of loads is applied that consists of internal pressure, residual stress and the soil loads. The influence of the loads is discussed. The non-pressure corrugated pipe is loaded by the soil loads only.


2011 ◽  
Vol 488-489 ◽  
pp. 303-306
Author(s):  
Jürgen Malzbender ◽  
G. Pećanac ◽  
Stefan Baumann

Ba0.5Sr0.5Co0.8Fe0.2O3 – δ is a mixed ion-electron conductor with high application potential as high-temperature gas separation membrane. However, in practical use the integrity of this brittle perovskite is challenged by the mechanical boundary conditions of transient temperature exposure. Moreover, long term failure mechanisms such as static fatigue at room temperature and creep rupture at operation temperature might occur. The relevance of both effects for BSCF has been investigated. The slow crack growth at room temperature has been determined using bi-axial bending under different loading rates. The creep rupture at elevated temperature has been analyzed from three-point bending tests. The results indicate favourable behaviour of BSCF in both cases. A low risk of failure due to slow crack growth exists and the strain to failure in combined tensile - compressive mode reaches up to 40 %.


2021 ◽  
Vol 5 (3) ◽  
pp. 67
Author(s):  
Jacques Lamon ◽  
Adrien Laforêt

The present paper investigates the static fatigue behavior of Hi-Nicalon fiber-reinforced SiC–SiC minicomposites at high temperatures in the 900–1200 °C range, and under tensile stresses above the proportional limit. The stress–rupture time relation was analyzed with respect to subcritical crack growth in filaments and fiber tow fracture. Slow crack growth from flaws located at the surface of filaments is driven by the oxidation of free carbon at the grain boundaries. Lifetime of the reinforcing tows depends on the statistical distribution of filament strength and on structural factors, which are enhanced by temperature increase. The rupture time data were plotted in terms of initial stresses on reinforcing filaments. The effect of temperature and load on the stress–rupture time relation for minicomposites was investigated using results of fractography and predictions of minicomposite lifetime using a model of subcritical growth for critical filaments. The critical filament is the one whose failure by slow crack-growth triggers unstable fracture of the minicomposite. This is identified by the strength–probability relation provided by the cumulative distribution function for filament strength at room temperature. The results were compared to the fatigue behavior of dry tows. The influence of various factors related to oxidation, including multiple failures, load sharing, and variability, was analyzed.


1992 ◽  
Vol 287 ◽  
Author(s):  
Chih-Kuang Jack Lin ◽  
Michael G. Jenkins ◽  
Matitison K. Ferber

ABSTRACTTensile fatigue behavior of a hot-isostatically-pressed (HIPed) silicon nitride was investigated over ranges of constant stresses, constant stress rates, and cyclic loading at 1150-1370°C. At 1150°C, static and dynamic fatigue failures were governed by a slow crack growth mechanism. Creep rupture was the dominant failure mechanism in static fatigue at 1260 and 1370°C. A transition of failure mechanism from slow crack growth to creep rupture appeared at stress rates ≤10−2 MPa/s for dynamic fatigue at 1260 and 1370°C. At 1 150-1370°C, cyclic loading appeared to be less damaging than static loading as cyclic fatigue specimens displayed greater failure times than static fatigue specimens under the same maximum stresses.


1996 ◽  
Vol 44 (2) ◽  
pp. 543-546 ◽  
Author(s):  
Jonas Salomonson ◽  
Kaiyang Zeng ◽  
David Rowcliffe

2010 ◽  
Vol 112 ◽  
pp. 129-140 ◽  
Author(s):  
O. Loseille ◽  
Jacques Lamon

Previous works have shown that ceramic matrix composites are sensitive to delayed failure during fatigue in oxidizing environments. The phenomenon of slow crack growth has been deeply investigated on single fibers and multifilament tows in previous papers. The present paper proposes a multiscale model of failure driven by slow crack growth in fibers, for 2D woven composites under a constant load. The model is based on the delayed failure of longitudinal tows. Additional phenomena involved in the failure of tows have been identified using fractographic examination of 2D woven SiC/SiC composite testspecimens after fatigue tests at high temperatures. Stochastic features including random load sharing, fiber overloading, fiber characteristics and fiber arrangement within the tows have been introduced using appropriate density functions. Rupture time predictions are compared to experimental data.


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