scholarly journals Time-Dependent Reliability of Ceramic Components Under Transient Loads

2000 ◽  
Author(s):  
Osama Jadaan ◽  
Noel Nemeth ◽  
Lynn Powers ◽  
Joe Palko ◽  
Eric Baker
Keyword(s):  
Crack Growth ◽  
Failure Modes ◽  
Slow Crack Growth ◽  
Thermal Conditions ◽  
Cyclic Fatigue ◽  
Growth Stress ◽  
Time Dependent ◽  
Start Up ◽  
Ceramic Components ◽  
Failure Conditions

Abstract Present capabilities of the NASA CARES/Life code include probabilistic life prediction of ceramic components subjected to fast fracture, slow crack growth (stress corrosion), and cyclic fatigue failure modes. Currently, this code has the capability to compute the time-dependent reliability of ceramic structures subjected to simple time-dependent loading. For example, in slow crack growth (SCG) type failure conditions CARES/Life can handle the cases of sustained and linearly increasing time-dependent loads, while for cyclic fatigue applications various types of repetitive constant amplitude loads can be accounted for. In real applications applied loads are rarely that simple, but rather vary with time in more complex ways such as, for example, engine start up, shut down, and dynamic and vibrational loads. In addition, when a given component is subjected to transient environmental and or thermal conditions, the material properties also vary with time. The objective of this paper is to demonstrate a methodology capable of predicting the time-dependent reliability of components subjected to transient thermomechanical loads that takes into account the change in material response with time. In this paper, the dominant delayed failure mechanism is assumed to be SCG. This methodology has been coded into CARES/Life, which has also been modified to have the capability of interfacing with commercially available FEA codes executed for transient load histories. An example involving a ceramic exhaust valve subjected to combustion cycle loads is presented to demonstrate the viability of this methodology and the CARES/Life program.

Slow Crack Growth in 3Y-TZP under Static and Cyclic Fatigue

1997 ◽  
Vol 132-136 ◽  
pp. 512-515 ◽  
Author(s):  
Jérôme Chevalier ◽  
C. Olagnon ◽  
Gilbert Fantozzi ◽  
J.M. Drouin ◽  
Bernard Calès
Keyword(s):  
Crack Growth ◽  
Slow Crack Growth ◽  
Cyclic Fatigue

A New Probabilistic Approach for Accurate Fatigue Data Analysis of Ceramic Materials

1999 ◽  
Author(s):  
Bjoern Schenk ◽  
Peggy J. Brehm ◽  
M. N. Menon ◽  
William T. Tucker ◽  
Alonso D. Peralta
Keyword(s):  
Data Analysis ◽  
Failure Modes ◽  
Probabilistic Approach ◽  
Time Dependent ◽  
Material Strength ◽  
Static Fatigue ◽  
Oak Ridge ◽  
Fatigue Data ◽  
Ceramic Components ◽  
Dependent Failure

Statistical methods for the design of ceramic components for time-dependent failure modes have been developed which can significantly enhance component reliability, reduce baseline data generation costs, and lead to more accurate estimates of slow crack growth (SCG) parameters. These methods are incorporated into the AlliedSignal Engines CERAMIC and ERICA computer codes. Use of the codes facilitates generation of material strength parameters and SCG parameters simultaneously, by pooling fast fracture data from specimens that are of different sizes, or stressed by different loading conditions, with data derived from static fatigue experiments. The codes also include approaches to calculation of confidence bounds for the Weibull and SCG parameters of censored data and for the predicted reliability of ceramic components. This paper presents a summary of this new fatigue data analysis technique and an example demonstrating the capabilities of the codes with respect to time-dependent failure modes. This work was sponsored by the U.S. Department of Energy Oak Ridge National Laboratory (DoE/ORNL) under Contract No. DE-AC05-84OR21400.

The Development of Life Prediction Techniques for Structural Ceramics

1996 ◽  
Vol 118 (4) ◽  
pp. 847-855
Author(s):  
P. K. Khandelwal ◽  
N. J. Provenzano ◽  
W. E. Schneider
Keyword(s):  
Crack Growth ◽  
Life Prediction ◽  
High Speed ◽  
Failure Modes ◽  
Slow Crack Growth ◽  
Ceramic Materials ◽  
Department Of Energy ◽  
Bending Stresses ◽  
Prediction Techniques ◽  
Fast Fracture

One of the major challenges involved in the use of ceramic materials in advanced vehicular heat engines is ensuring adequate strength and durability. This Department of Energy supported activity has developed methodologies to predict the structural behavior of ceramic components. The effort involved the characterization of injection-molded and hot isostatic pressed PY6 silicon nitride and the development of analytical life prediction techniques. Three failure modes are addressed: fast fracture, slow crack growth, and creep rupture. The technique deals with surface as well as internal component failures. The life prediction methodologies for fast fracture and slow crack growth have been verified using two types of confirmatory specimens: (1) flat circular disks subjected to bending stresses, and (2) high-speed rotating spin disks. Correlation was achieved for a variety of test conditions and failure mechanisms. The predictions associated with surface failures proved to be optimistic, requiring re-evaluation of the components’ initial fast fracture strength. Correlation was achieved for the spin disks that failed in fast fracture from internal flaws. Time-dependent, elevated-temperature spin disk failures were also successfully predicted.

scholarly journals Time-dependent rupture and slow crack growth: elastic and viscoplastic dynamics

2009 ◽  
Vol 42 (21) ◽  
pp. 214007 ◽  
Author(s):  
Loïc Vanel ◽  
Sergio Ciliberto ◽  
Pierre-Philippe Cortet ◽  
Stéphane Santucci
Keyword(s):  
Crack Growth ◽  
Slow Crack Growth ◽  
Time Dependent

Assessment of Slow Crack Growth Test Methodologies Used to Predict Service Life of High Density Polyethylene Piping

2013 ◽  
Author(s):  
S. Kalyanam ◽  
P. Krishnaswamy ◽  
D.-J. Shim ◽  
Y. Hioe ◽  
S. Kawaguchi ◽  
...  
Keyword(s):  
Stress Intensity Factor ◽  
Stress Intensity ◽  
Service Life ◽  
Intensity Factor ◽  
Crack Growth ◽  
Failure Modes ◽  
Slow Crack Growth ◽  
Failure Times ◽  
Hdpe Pipe ◽  
T Stress

HDPE pipe and piping components have been used successfully and safely for natural gas distribution around the world for several decades. The primary concerns for a 50-year life for buried HDPE piping involves designing against three primary failure modes — ductile fracture, rapid crack propagation (RCP), and slow crack growth (SCG) under sustained pressure loading. Although design methodologies for preventing ductile fracture, and RCP are well established, SCG remains to be a limiting failure mode in determining useful service life of HDPE piping as it may occur under sustained pressure and temperature. Although considerable amount of research has been conducted over the last two decades, SCG still remains less well understood than other failure modes. A critical evaluation of various test methodologies available to determine the SCG resistance of HDPE resins was conducted using FEA of various widely used laboratory test specimens. While there exist extensive information on the test methodologies and the applicability of each of the SCG testing methods, there is a growing concern as to whether any/all of these SCG tests give the same information akin to the industrial pipe application, particularly so when conflicting messages are obtained from time to failure predictions from two different SCG tests. While notched-pipe test (NPT) proves to be a direct approach to assess SCG resistance of the PE pipe with the use of temperature as a test accelerating factor; in the case of newer grade PE resins, the failure time of NPT can still be considerably large (∼5,000 to 10,000 hours). For this reason, some of the other coupon SCG tests are focus of recent investigations and especially sought after for rapid ranking/assessment of resins and understanding the manufactured HDPE pipe performance. In this study, FEA was conducted to facilitate a direct comparison of leading SCG test methods, through determination of both the stress intensity factor, KI, and existing constraint factors in various widely used specimen geometries. These results are then compared to pipe specimen with an OD (outer diameter) or ID (inner diameter) surface notch. Since, constraint can have a significant role in SCG initiation, T-stress, and biaxiality ratios (β), these were compared along the crack fronts to arrive at definitive reasons for the smaller failure times observed when testing some of the SCG test specimens, and also reasons for SCG mode of failure observed even under large applied loads (large KI compared to that in a notched pipe) when testing some of the SCG test specimens. The use of stress intensity factor, KI, along with the T-stress and biaxiality ratio (β), is found to provide a complete picture on the broad spectrum of failure times observed from various SCG test specimens and rationale for choosing a SCG test specimen when evaluating HDPE pipe or resins.

Adhesion and Reliability of Epoxy/Glass Interfaces

2000 ◽  
Vol 123 (4) ◽  
pp. 401-404 ◽  
Author(s):  
John E. Ritter ◽  
Armin Huseinovic
Keyword(s):  
Fatigue Crack ◽  
Cyclic Loading ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Slow Crack Growth ◽  
Cyclic Fatigue ◽  
Aqueous Environments ◽  
Crack Tip Plasticity ◽  
Static And Cyclic Loading ◽  
Microelectronic Components

The reliability of microelectronic components is profoundly influenced by the fracture resistance of the polymer/inorganic interfaces and by the progressive debonding of these interfaces in aqueous environments. Consequently, fatigue (slow) crack growth in epoxy/glass interfaces bonded with the silane coupling agent 3-aminopropyltriethoxysilane (3-APES) was studied under static and cyclic loading at 23°C and in either dry or humid conditions using the double cleavage drilled compression (DCDC) test. Crack growth rates under cyclic loading were significantly greater than under static loading, indicating that stress corrosion effects are negligible and that crack tip plasticity controls cyclic fatigue crack growth at silane (3-APES) bonded epoxy/glass interfaces. After aging at 94°C in water, these silane bonded epoxy/glass interfaces exhibited somewhat greater resistance to cyclic fatigue crack growth than the unaged samples; however, after aging at 98°C in water cyclic fatigue crack growth became cohesive and fractal in nature. Mechanisms for fatigue crack growth at silane (3-APES) bonded epoxy/glass interfaces are discussed.

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.

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