Shielding Effect Rule of Thermal Fatigue Crack Net and Calculating Method of Stress Intensity Factor of Main Crack

2009 ◽  
Vol 45 (12) ◽  
pp. 279 ◽  
Author(s):  
Ming YAN
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Thermal Fatigue ◽  
Main Crack ◽  
Shielding Effect ◽  
Thermal Fatigue Crack ◽  
Calculating Method

Stress Intensity Factor of Thermal Fatigue Crack in High Temperature

2012 ◽  
Vol 581-582 ◽  
pp. 677-680
Author(s):  
Ming Yan ◽  
Hao Chuan Li ◽  
Lin Li
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
High Temperature ◽  
Stress Intensity ◽  
Low Temperature ◽  
Intensity Factor ◽  
Thermal Fatigue ◽  
Kinematic Hardening ◽  
Temperature Cycle ◽  
Thermal Fatigue Crack

Stress intensity factor of thermal fatigue crack was calculated within one cycle by using finite element method in consideration of the multi-linear kinematic hardening characteristic of a material. The affection of loading sequence to stress intensity factor was studied under circularly variational temperature by comparing to that in one cycle. The low temperature cycle can not affect the stress intensity factor of latter cycles with high temperature; but high temperature cycle can affect the stress intensity factor of latter cycles with low temperature, and make it be equal to that of the high temperature cycle.

Extended finite element method analysis for shielding and amplification effect of a main crack interacted with a group of nearby parallel microcracks

2014 ◽  
Vol 25 (1) ◽  
pp. 4-25 ◽  
Author(s):  
Heng Wang ◽  
Zhanli Liu ◽  
Dandan Xu ◽  
Qinglei Zeng ◽  
Zhuo Zhuang
Keyword(s):  
Finite Element Method ◽  
Stress Intensity Factor ◽  
Finite Element ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Main Crack ◽  
Extended Finite Element Method ◽  
Shielding Effect ◽  
Extended Finite Element ◽  
Element Method

The shielding and amplification effects of transverse array of microcracks on a main crack are investigated using extended finite element method. The interaction between macrocracks and microcracks is quantitatively characterized in terms of the stress intensity factor which is calculated by the interaction integral method and the complete stress field in the entire domain could be given without remeshing. Various distributions of microcracks with different number, location, and density are considered. For a microcrack collinear to the main crack, the numerical results agree quite well with the analytical solution. Interestingly, the shielding and amplification effects display periodicity when the main crack is placed inside the microcrack rows. In particular, the minimum stress intensity factor of the main crack which refers to the maximum shielding effect is primarily determined by the nearest microcracks. However, the maximum stress intensity factor is largely affected by the distribution and density of microcracks and even could be turned from enhancement to shielding. The results are consistent with the microcrack-toughening phenomenon observed in the experiments and are meaningful for the design of new microstructure-toughening materials.

Effect of Temperature on Fatigue Crack Growth in CPVC

2003 ◽  
Vol 125 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Muhammad Irfan-ul-Haq ◽  
Nesar Merah
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Effect Of Temperature ◽  
Stress Intensity Factor Range ◽  
Crack Growth Behavior ◽  
Different Temperatures

This study addresses the effect of temperature on fatigue crack growth (FCG) behavior of CPVC. FCG tests were conducted on CPVC SEN tensile specimens in the temperature range −10 to 70°C. These specimens were prepared from 4-in. injection-molded pipe fittings. Crack growth behavior was studied using LEFM concepts. The stress intensity factor was modified to include the crack closure and plastic zone effects. The effective stress intensity factor range ΔKeff gave satisfactory correlation of crack growth rate (da/dN) at all temperatures of interest. The crack growth resistance was found to decrease with temperature increase. The effect of temperature on da/dN was investigated by considering the variation of mechanical properties with temperature. Master curves were developed by normalizing ΔKeff by fracture strain and yield stress. All the da/dN-ΔK curves at different temperatures were collapsed on a single curve. Crazing was found to be the dominant fatigue mechanism, especially at high temperature, while shear yielding was the dominant mechanism at low temperatures.

Mechanisms of Fatigue Crack Growth in WC-Co Cemented Carbides

2005 ◽  
Vol 297-300 ◽  
pp. 1120-1125 ◽  
Author(s):  
Myung Hwan Boo ◽  
Chi Yong Park
Keyword(s):  
Growth Rate ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Stress Ratio ◽  
Cemented Carbides ◽  
Stress Intensity Factor Range

In order to study the influence of stress ratio and WC grain size, the characteristics of fatigue crack growth were investigated in WC-Co cemented carbides with two different grain sizes of 3 and 6 µm. Fatigue crack growth tests were carried out over a wide range of fatigue crack growth rates covering the threshold stress intensity factor range DKth. It was found that crack growth rate da/dN against stress intensity factor range DK depended on stress ratio R. The crack growth rate plotted in terms of effective stress intensity factor range DKeff still exhibited the effect of microstructure. Fractographic examination revealed brittle fracture at R=0.1 and ductile fracture at R=0.5 in Co binder phase. The amount of Co phase transformation for stress ratio was closely related to fatigue crack growth characteristics.

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