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Crack Size (crack + size)

Distribution by Scientific Domains

Polymers and Materials Science	100%

Selected Abstracts

Fatigue life prediction of cracked padded plates

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 3-4 2008
K. GUO
ABSTRACT The fatigue crack propagation analyses of padded plates are conducted to predict the crack growth behaviour under various loading conditions. The fatigue life of a padded plate with a single edge crack originating from the weld toe is calculated using the weight function approach. The fatigue strength of padded plates with different pad thickness under remote loading conditions was investigated and compared to the T-plate joint. The improvement of the fatigue strength of the pad design is verified. The thickness effect of the padded plate was investigated using the fracture mechanics approach. The geometrically similar model pairs with different initial crack sizes were investigated under remote loading conditions. It was shown that the thickness effect depends on both stress concentration and initial crack size. [source]

Effect of shot peening on fatigue limit of surface flawed samples

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 3-4 2008
F. TAKAHASHI
ABSTRACT The effects of shot peening on the fatigue limit of specimens having a semicircular notch of varied surface length, 2a, are investigated. In the case of un-peened specimens, the fatigue limit of specimens having a notch of a= 0.05 mm was equal to that of the un-notched specimens. However, the fatigue limit of a= 0.3 mm was 46% smaller than that of the un-notched specimens. On the contrary, in the case of peened specimens, the fatigue limit of a= 0.2 mm was equal to that of the un-notched specimens and furthermore, that of a= 0.3 mm was only 5% smaller than that of the un-notched specimens. Multiple non-propagating cracks were observed in peened specimens after fatigue testing. The stress intensity factor of the maximum non-propagating crack size corresponded to that of a= 0.2 mm notch. These results indicate that shot peening increases fatigue limit and decreases the likelihood that a surface flaw will result in failure. [source]

A probabilistic simulation of fluid leakage in multiple cracks situation

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 11 2002
L. XIE
ABSTRACT In pressure vessels and piping the leak-before-break (LBB) assessment method is employed to avoid any catastrophic failure prior to a detectable leakage. One of the most important parameter, the leak rate, is investigated in the present paper by means of the Monte Carlo method. A brief review is carried out with emphasis on aspects such as crack growth, crack size with detectable leakage, crack opening area and leak rate. Issues concerning the property and behaviour of multiple cracks are also covered along with a review of the characteristics of leak rate through distributed multiple cracks using a statistical simulation method. The simulation results show that the effect of multiple cracks is quite significant to the LBB concept. Both the relationship between leak rate and crack length (or time) and the statistical characteristics of the leak rate are considerably different for different initial crack conditions. [source]

Small crack growth in combined bending,torsion fatigue of A533B steel

FATIGUE & FRACTURE OF ENGINEERING MATERIALS AND STRUCTURES, Issue 3 2001
J. Park
Crack growth rate data from bending, torsional and in-plane and 90° out-of-phase combined bending,torsional fatigue tests of A533B steel are presented. Crack growth was monitored from initial sizes generally in the range of 50,300 ,m to final sizes of several millimetres. Crack growth rate was found to vary linearly with crack size. Two approaches for correlating the A533B crack growth rate were evaluated, an effective strain-based intensity factor range and a method based on total cyclic strain energy density. The approaches were also evaluated using small crack growth data from the literature for SAE 1045 steel and Inconel 718 specimens tested under axial,torsional loadings. Predicted crack growth lives using both approaches were found to agree within a factor of two of observed lives for nearly all of the data examined. [source]

Crack-Healing Behavior of Liquid-Phase-Sintered Silicon Carbide Ceramics

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 3 2003
Young-Wook Kim
Crack-healing behavior of liquid-phase-sintered (LPS) SiC ceramics has been studied as functions of heat-treatment temperature and crack size. Results showed that heat treatment in air could significantly increase the indentation strength. The heat-treatment temperature has a profound influence on the extent of crack healing and the degree of strength recovery. The optimum heat-treatment temperature depends on the softening temperature of an intergranular phase in each material. After heat treatment at the optimum temperature in air, the crack morphology almost entirely disappeared and the indentation strength recovered to the value of the smooth specimens at room temperature for the investigated crack sizes up to ,200 ,m. In addition, a simple heat treatment of SiC ceramics sintered with Al2O3,Y2O3,CaO at 1100°C for 1 h in air resulted in even further improvement of the strength, to a value of 1054 MPa (,150% of the value of the unindented strength). Crack closure and rebonding of the crack wake due to oxidation of cracked surfaces were suggested as a dominant healing mechanism operating in LPS-SiC ceramics. [source]

Fatigue life prediction of cracked padded plates

Crack-Healing Behavior of Liquid-Phase-Sintered Silicon Carbide Ceramics

Crack Healing Behavior of Silicon Carbide Ceramics

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 11 2000
Jan Korou
This study focuses on the crack healing behavior of three kinds of commercial SiC ceramics. Specimens with and without cracks were subjected to thermal treatment at different temperatures, and their strengths were measured by a three-point bending test in accordance with JIS standards. The tests were performed in air at both room temperature and elevated temperatures between 600° and 1500°C. The healed specimens showed a complete recovery of strength at room temperature for the investigated crack sizes of 2c, 100 ,m and 2c, 200 ,m, and their strength increased in accordance with the healing temperature. The behavior of the healed specimens at elevated temperatures was influenced by the material used and the test temperature. Generally, the strength decreased at a high temperature, but the degree of strength reduction was determined by the kind of ceramic. The most important difference between the healed and smooth specimens was exhibited in material A. It was observed that at 1400°C, the bending strength of the healed specimens made from this ceramic was about 37% of the value for specimens in an as-received state. Static fatigue tests were also performed for ceramic B at 900° and 1000°C. The experiment demonstrated that the static fatigue limit of a healed specimen is about 75% of the monotonic bending strength at the same temperature. [source]