Contributions of Time Dependent and Cyclic Crack Growth to the Crack Growth Behavior of Non Strain-Crystallizing Elastomers

2002 ◽  
Vol 75 (4) ◽  
pp. 643-656 ◽  
Author(s):  
J. J. C. Busfield ◽  
K. Tsunoda ◽  
C. K. L. Davies ◽  
A. G. Thomas
Keyword(s):  
Crack Growth ◽  
Growth Behavior ◽  
Time Dependent ◽  
Crack Growth Behavior ◽  
Wide Range ◽  
Dependent Component ◽  
Tearing Energy ◽  
Quasi Crystals ◽  
Crack Growth Rates ◽  
Time Dependent Crack Growth

Abstract Engineering components are observed to fail more rapidly under cyclic loading than under static loading. This reflects features of the underlying crack growth behavior. This behavior is characterized by the relation between the tearing energy, T, and the crack growth per cycle, dc/dn. The increment of crack growth during each cycle is shown here to result from the sum of time dependent and cyclic crack growth components. The time dependent component represents the crack growth behavior that would be present in a conventional constant T crack growth test. Under repeated stressing additional crack growth, termed the cyclic crack growth component, occurs. For a non-crystallizing elastomer, significant effects of frequency have been found on the cyclic crack growth behavior, reflecting the presence of this cyclic element of crack growth. The cyclic crack growth behavior over a wide range of frequencies was investigated for unfilled and swollen SBR materials. The time dependent crack growth component was calculated from constant T crack growth tests and the cyclic contribution derived from comparison with the observed cyclic growth. It is shown that decreasing the frequency or increasing the maximum tearing energy during a cycle results in the cyclic crack growth behavior being dominated by time dependent crack growth. Conversely at high frequency and at low tearing energy, cyclic crack growth is dominated by the cyclic crack growth component. A large effect of frequency on cyclic crack growth behavior was observed for highly swollen SBR. The cyclic crack growth behavior was dominated by the time dependent crack growth component over the entire range of tearing energy and/or crack growth rate. The origin of the cyclic component may be the formation/melting of quasi crystals at the crack tip, which is absent at fast crack growth rates in the unswollen SBR and is absent at all rates in the swollen SBR.

Time-dependent crack growth behavior for a SMAW weldment of Gr. 91 steel

2013 ◽  
Vol 110 ◽  
pp. 66-71 ◽  
Author(s):  
Woo-Gon Kim ◽  
Jae-Young Park ◽  
Hyeong-Yeon Lee ◽  
Sung-Deok Hong ◽  
Yong-Wan Kim ◽  
...  
Keyword(s):  
Crack Growth ◽  
Growth Behavior ◽  
Time Dependent ◽  
Crack Growth Behavior ◽  
Time Dependent Crack Growth

Non-Relaxing Crack Growth and Fatigue in a Non-Crystallizing Rubber

1974 ◽  
Vol 47 (5) ◽  
pp. 1253-1264 ◽  
Author(s):  
P. B. Lindley
Keyword(s):  
Crack Growth ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Maximum Deformation ◽  
Fatigue Data ◽  
Tentative Explanation ◽  
Tearing Energy ◽  
Relationship Of ◽  
The Relationship ◽  
Unique Relationship

Abstract The crack growth behavior of a non-crystallizing rubber, SBR, is investigated in terms of the tearing energy T, the energy available for crack growth. For cyclic deformations in which the minimum tearing energy is zero (relaxing conditions), a unique relationship is obtained between the growth per cycle and T at the maximum deformation. This rubber also exhibits crack growth at constant tearing energies. The relationship of the crack growth rate as a function of tearing energy, when the minimum tearing energy of the cycle is not zero, can be superimposed on the relaxing relationship by scaling the rates, and a tentative explanation is proposed for the scaling factor. Fatigue data are consistent with this.

Transient Crack Growth Behavior Under Cycle/Time-Dependent Step Loading for Pb-Containing and Pb-Free Solders

2013 ◽  
Vol 42 (12) ◽  
pp. 3593-3608 ◽  
Author(s):  
Kittichai Fakpan ◽  
Yuichi Otsuka ◽  
Yukio Miyashita ◽  
Yoshiharu Mutoh ◽  
Kohsoku Nagata
Keyword(s):  
Crack Growth ◽  
Cycle Time ◽  
Growth Behavior ◽  
Time Dependent ◽  
Crack Growth Behavior ◽  
Step Loading

Fatigue Crack Growth Behavior of Four Structural Alloys in High Temperature High Purity Oxygenated Water

1979 ◽  
Vol 101 (3) ◽  
pp. 191-198 ◽  
Author(s):  
D. A. Hale ◽  
C. W. Jewett ◽  
J. N. Kass
Keyword(s):  
Fatigue Crack ◽  
High Temperature ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Growth Rates ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Fatigue Crack Growth Behavior ◽  
Oxygenated Water ◽  
Crack Growth Rates

The fatigue crack growth behavior of four structural alloys was studied and the effects of high temperature (288°C), high purity oxygenated water, cycle frequency, and mean stress were evaluated. The results for carbon and low alloy steel show that while crack growth rates are affected by the water environment, modified ASME code procedures result in conservative predictions of growth. Often, higher crack growth rates are found for shallow cracks than for deep cracks. For stainless steels and Inconel the measured growth rates in water were similar to data obtained in air over the range of cycle frequencies studied.

A Superposition Approach for Time-Dependent Fatigue Crack Growth

2012 ◽  
Author(s):  
Fashang Ma
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Growth Rates ◽  
Time Dependent ◽  
Crack Growth Rates ◽  
Time Dependent Crack Growth

High temperature fatigue crack growth is a combination of fatigue, creep and environmental attack, which greatly enhance fatigue crack growth. In order to understand the damage mechanisms and develop a physically based crack growth model, systematic experimental research has been conducted under various loading conditions for different specimen geometries made from a high strength nickel alloy. Test results from this work showed that time-dependent fatigue crack growth rates differ significantly from those observed in conventional fatigue crack growth tests. Crack geometry and loading history significantly affect fatigue crack growth rate. These results suggest the need for a change in the K based superposition approach for time-dependent crack growth modeling. A phenomenological model has been developed to predict time-dependent crack growth under various loading histories and crack geometries. In this model an effective stress intensity factor is defined to account for the effects of constraint loss of fracture mechanics due to crack-tip plasticity, and the creep stress relaxation on stress intensity factor. It is found the model can accurately predict the dwell crack growth rates for different crack geometries under various loading conditions.

Crack Growth Behavior in Alloy 718 at 425°C

1978 ◽  
Vol 100 (4) ◽  
pp. 381-387 ◽  
Author(s):  
K. Sadananda ◽  
P. Shahinian
Keyword(s):  
Crack Growth ◽  
High Stress ◽  
Growth Behavior ◽  
Time Dependent ◽  
Crack Growth Behavior ◽  
Limiting Factor ◽  
Alloy 718 ◽  
Linear Elastic ◽  
Combined Loads ◽  
Cycle Dependent

Subcritical crack growth behavior in Alloy 718 was studied at 425°C under static, cyclic, and combined loads. The results are analyzed using linear elastic fracture mechanics. Crack growth was shown to be cycle-dependent at all stress intensities at this temperature and hold times up to 10 min have no effect on the crack growth rates. On the other hand, crack growth is shown to occur readily under static loads at stress intensities less than half of the fracture toughness value. Comparison of the present results with those published in the literature showed that while crack growth is cycle-dependent at 425°C and time-dependent at 650°C, at an intermediate temperature, 540°C, it is time-dependent at low stress intensities and cycle-dependent at high stress intensities. Extrapolation of the present data shows that crack growth under static load could occur at temperatures above approximately 350°C and this may be a limiting factor for Alloy 718 for some of its high temperature applications.

Crack Growth Characteristics Evaluation Method in Ceramics Based on DT Technique

2008 ◽  
Vol 47-50 ◽  
pp. 250-253 ◽  
Author(s):  
Tokunaga Hitoo ◽  
Hiroyuki Kinoshita ◽  
Kiyohiko Ikeda ◽  
Koichi Kaizu
Keyword(s):  
Growth Rate ◽  
Crack Growth Rate ◽  
Crack Growth ◽  
Evaluation Method ◽  
Growth Characteristic ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Soda Lime Glass ◽  
Single Experiment ◽  
Wide Range

A new method to evaluate the relationship between stress intensity factor KI and crack growth rate V of ceramics which is based on Double-Torsion (DT) technique was proposed. Materials were soda-lime glass, glass ceramics and alumina ceramics. Plate type DT specimens were prepared, and rectangular section guide groove was introduced in the upper surface of specimen. As a crack propagation test, a constant loading rate test was performed. Furthermore, a crack growth behavior was monitored by a compliance method. As the results, it was found that the clack growth behavior can be detected with high accuracy by using the proposed method. And it was confirmed that crack growth characteristic over wide range of crack growth rate can be evaluated by single experiment. Furthermore, since the method is based on a simple measurement system, it is considered that the method has a good availability for KI-V evaluation in ceramics.

High Temperature Crack Growth Behavior of 304 Stainless Steel under Creep and Fatigue Loading

2005 ◽  
Vol 297-300 ◽  
pp. 452-457
Author(s):  
Y.M. Baik ◽  
K.S. Kim
Keyword(s):  
Stainless Steel ◽  
Crack Growth ◽  
Growth Rates ◽  
Hold Time ◽  
Fatigue Loading ◽  
Growth Behavior ◽  
304 Stainless Steel ◽  
Crack Growth Behavior ◽  
Creep Fatigue ◽  
Crack Growth Rates

The crack growth behavior in a 304 stainless steel has been investigated at 538°C in air environment. Compact tension specimens were subjected to fatigue, creep and creep-fatigue loading. The combined effects on crack growth rates of load level and hold time have been examined. Stress intensity factors are found to correlate crack growth rates reasonably well for fatigue crack growth. Creep crack growth rates are found to correlate with stress intensity factor and C*(t). Crack growth rates under hold time cycles are successfully correlated with C*(t)avg under various load levels and hold times. Crack growth under creep-fatigue loading has been simulated by elastic-plastic-steady state creep finite element analyses. The results of analysis show that fatigue loading interrupts stress relaxation around the crack tip during hold time and causes stress reinstatement, thereby giving rise to accelerated crack growth compared with crack growth under static loading. Analysis of hold time crack growth based on the cyclic stress-strain response yields crack closure during unloading, and creep deformation during hold time tends to lower the closure load.

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