scholarly journals Statistical-Probabilistic Approach to the Lifetime and Strength Degradation of E-Glass Filaments and Bundles under Constant Tensile Loading in Water

2019 ◽  
Vol 3 (3) ◽  
pp. 78
Author(s):  
Jacques Lamon ◽  
Mohamed R’Mili
Keyword(s):  
Crack Growth ◽  
Slow Crack Growth ◽  
Probabilistic Approach ◽  
Tensile Tests ◽  
Fatigue Behaviour ◽  
Strength Degradation ◽  
Tensile Behaviour ◽  
Static Fatigue ◽  
Statistical Parameters ◽  
Pertinent Data

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.

Slow Crack Growth of a Pyroceram Glass Ceramic Under Static Fatigue Loading: Commonality of Slow Crack Growth in Advanced Ceramics

2014 ◽  
Author(s):  
Sung R. Choi ◽  
D. Calvin Faucett ◽  
Brenna Skelley
Keyword(s):  
Crack Growth ◽  
Glass Ceramic ◽  
Life Prediction ◽  
Elevated Temperatures ◽  
Slow Crack Growth ◽  
Static Fatigue ◽  
Fatigue Data ◽  
Prediction Approach ◽  
Applied Stresses ◽  
Dynamic Fatigue

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.

Slow Crack Growth of a Pyroceram Glass Ceramic Under Static Fatigue Loading—Commonality of Slow Crack Growth in Advanced Ceramics

2014 ◽  
Vol 137 (3) ◽  
Author(s):  
Sung R. Choi ◽  
D. Calvin Faucett ◽  
Brenna Skelley
Keyword(s):  
Crack Growth ◽  
Glass Ceramic ◽  
Life Prediction ◽  
Elevated Temperatures ◽  
Slow Crack Growth ◽  
Static Fatigue ◽  
Fatigue Data ◽  
Prediction Approach ◽  
Applied Stresses ◽  
Dynamic Fatigue

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.

Slow Crack Growth and Creep Rupture of Ba0.5Sr0.5Co0.8Fe0.2O3 – δ

2011 ◽  
Vol 488-489 ◽  
pp. 303-306
Author(s):  
Jürgen Malzbender ◽  
G. Pećanac ◽  
Stefan Baumann
Keyword(s):  
Crack Growth ◽  
Room Temperature ◽  
Slow Crack Growth ◽  
Creep Rupture ◽  
Transient Temperature ◽  
Static Fatigue ◽  
Operation Temperature ◽  
Separation Membrane ◽  
Application Potential ◽  
Temperature Exposure

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 %.

scholarly journals Static Fatigue of SiC/SiC Minicomposites at High Temperatures up to 1200 °C in Air: Multiscale Approach

2021 ◽  
Vol 5 (3) ◽  
pp. 67
Author(s):  
Jacques Lamon ◽  
Adrien Laforêt
Keyword(s):  
Crack Growth ◽  
High Temperatures ◽  
Fatigue Behavior ◽  
Slow Crack Growth ◽  
Stress Rupture ◽  
Rupture Time ◽  
Cumulative Distribution ◽  
Initial Stresses ◽  
Static Fatigue ◽  
Time Relation

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.

Evaluation of Tensile Static, Dynamic, and Cyclic Fatigue Behavior for A Hiped Silicon Nitride at Elevated Temperatures

1992 ◽  
Vol 287 ◽  
Author(s):  
Chih-Kuang Jack Lin ◽  
Michael G. Jenkins ◽  
Matitison K. Ferber
Keyword(s):  
Silicon Nitride ◽  
Cyclic Loading ◽  
Crack Growth ◽  
Failure Mechanism ◽  
Fatigue Behavior ◽  
Slow Crack Growth ◽  
Cyclic Fatigue ◽  
Creep Rupture ◽  
Static Fatigue ◽  
Dynamic Fatigue

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.

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

2006 ◽  
Vol 2006 (0) ◽  
pp. 101
Author(s):  
Hitoo Tokunaga ◽  
Kiyohiko Ikeda ◽  
Gang Deng ◽  
Hiroyuki Kinoshita ◽  
Koichi kaizu
Keyword(s):  
Residual Stress ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
Static Fatigue ◽  
Tempered Glass

Fracture and Fatigue Behaviour of Mullite/Molybdenum Composites

2005 ◽  
Vol 290 ◽  
pp. 110-120 ◽  
Author(s):  
Y. Torres Hernández ◽  
Marc Anglada ◽  
Luis Llanes ◽  
J.F. Bartolomé ◽  
M. Díaz ◽  
...  
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Crack Growth Rate ◽  
Fatigue Behaviour ◽  
Mechanical Degradation ◽  
Static Fatigue ◽  
Cyclic Loads

The fracture and fatigue behaviour of a mullite/molybdenum composite is investigated. The attention is focused on the measurement of fracture toughness, KIc, on long through the thickness cracks by using SENB specimens, and on the growth of indentation cracks under static, monotonic and cyclic loads. Molybdenum was chosen to reinforce the mullite matrix because of the similar thermal expansion coefficients for both phases. It is essential to know and take into account the shape of the initial indentation cracks as well as the eccentricity change after extension under monotonic and cyclic stress. This study shows that, in mullite/molybdenum composites, static fatigue effects are negligible, but these composites are susceptible to mechanical degradation under cyclic loads. It is shown that the fatigue crack growth rate exhibits a high dependence on Kmax and that the fatigue sensitivity, defined as the ratio between fatigue crack growth rate threshold and KIc, is much lower than for other materials processed by powder metallurgy.

Prediction of Lifetime in Static Fatigue at High Temperatures for Ceramic Matrix Composites

2010 ◽  
Vol 112 ◽  
pp. 129-140 ◽  
Author(s):  
O. Loseille ◽  
Jacques Lamon
Keyword(s):  
Crack Growth ◽  
High Temperatures ◽  
Slow Crack Growth ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Woven Composites ◽  
Static Fatigue ◽  
Matrix Composites ◽  
Random Load ◽  
Delayed Failure

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.

Fracture Morphologies of Carbon-Black-Loaded SBR Subjected to Low-Cycle, High-Stress Fatigue

1989 ◽  
Vol 62 (2) ◽  
pp. 272-287 ◽  
Author(s):  
Alfred Goldberg ◽  
Donald R. Lesuer ◽  
Jacob Patt
Keyword(s):  
Carbon Black ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
High Stress ◽  
Strength Loss ◽  
Tensile Tests ◽  
Constant Load ◽  
Low Carbon ◽  
Definition Of ◽  
Cyclic Damage

Abstract In the absence of a mechanical defect at the surface, failure is almost always initiated in the bulk of a sample at a material flaw. A variety of flaw morphologies are observed; however, the extent of cyclic damage could not be related to either flaw size or flaw type. Energy dispersive spectographic analysis did not reveal any differences in chemistry between a flaw site and regions remote from a flaw. The size and definition of a flaw increase with an increase in carbon-black loading. Initiation flaw sites are enveloped by fan-shaped or penny-shaped regions which develop during cycling. With the highly loaded carbon-black samples, these regions consist of concentric bands which increase in number and become more prominent with an increase in test temperature. This is attributed to the presence of knotty tearing. With low carbon-black loadings, the absence of any significant disorientations in the tearing paths during either a cycle or a series of cyclic events results in the absence of individual resolvable bands within the fatigue-tear regions. The size and morphology of a fatigue-tear region appears to be independent of the fatigue load or the extent of the damage (strength loss). By contrast, either an increase in cycling load or an increase in damage at constant load increases the definition of the fatigue-region morphology for all formulations of carbon black. The morphologies in regions leading to failure during the final cycle are identical to the morphologies of fractured surfaces obtained in conventional tensile tests—tear steps or ridges at low magnifications and slow crack-growth with coarse tear paths and fast crack-growth with fine tear paths at high magnifications. Morphologies typical of slow crack-growth are also seen within the banded (fatigue) regions. On the finest scale, the morphology can be described in terms of tearing of individual groups of rubber strands, collapsing to form a cell-like structure.

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