Coupling Analysis of Vibration and Fatigue Crack Propagation for a Breathing Cracked Beam

2012 ◽  
Vol 164 ◽  
pp. 338-343 ◽  
Author(s):  
Wei Cui ◽  
Jian Jun Wang

The coupling effect of vibration and fatigue crack propagation for a cracked cantilever beam is studied in this paper. The dynamic characteristics and fracture mechanics parameters are calculated by using 2D 8-nodes elements in FEM code. The nonlinear dynamic behavior of breathing crack is described by a frictionless contact FEM model. Linear fracture mechanics theory is used to calculate the stress intensity factor. At resonant state, coupling effect is significant between vibration and crack propagation. The response of beam under harmonic excitation is extremely sensitive to the structure natural frequency decrease which is caused by crack length growth. An approach of sweeping crack length analysis is proposed in resonant response evaluation of cracked beam. Two numerical tests are calculated to investigate coupling effects at resonant state: crack arrest problem and crack unstable propagation problem.

1976 ◽  
Vol 98 (4) ◽  
pp. 296-304 ◽  
Author(s):  
R. Koterazawa ◽  
Y. Iwata

A fracture mechanics and fractographic study was conducted on creep and fatigue crack propagation of a 304 stainless steel under constant and repeated tensile stress at a temperature of 650°C. Linear elastic fracture mechanics could be applied to the test data fairly successfully in spite of the fact that the tests were conducted under creep conditions. A comparison with data in a literature indicated that this is not true for bending-type specimens such as the compact tension specimen because of redistribution of bending stress due to creep, and therefore a specimen geometry which avoids bending stress is preferred for creep crack testing. Under repeated stress, the crack generally started as a transgranular fatigue crack and changed to an intergranular creep crack at some length of the crack. The transition point moved to a later stage of crack propagation as the period of repeated stress increased. This transition phenomenon could be explained by assuming that the two crack propagation processes, the transgranular fatigue crack and the intergranular creep crack, are possible under repeated stress condition and that the one with the higher rate actually occurs.


2012 ◽  
Vol 204-208 ◽  
pp. 3016-3021
Author(s):  
Zheng Wen Jiang ◽  
Shui Wan ◽  
Chen Cheng

Abstract. The fatigue crack propagation life-span of the engineering structure is studied. Linear elastic fracture mechanics is applied to analyze the life-span of fatigue crack growth of specimen, which is under constant amplitude load. The software of Fatigue is used to calculate the life-span of a center crack plate steel specimen. The result show that the calculated values of the life-span are basically well with the experimental data.


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