Numerical Simulation of Fatigue Crack Propagation Under Simulated Whipping Loading Arising in Hull Structures

2013 ◽  
Author(s):  
Kazuki Matsuda ◽  
Koji Gotoh
Keyword(s):  
Numerical Simulation ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Loading History ◽  
Stress Criterion ◽  
Fatigue Crack Propagation Behavior ◽  
Propagation Behavior ◽  
Cycle Count ◽  
Frequency Components

Fatigue crack propagation behavior under simulated whipping loadings which contain two different frequency components is highlighted. Numerical simulation of fatigue crack propagation based on an advanced fracture mechanics approach using the RPG (Re-tensile Plastic zone Generating) stress criterion for fatigue crack propagation is improved to enable the extraction of the effective loading history. The critical value of the plastic hysteresis for the stress versus strain relationship occurring in the vicinity of a crack tip is defined as the control parameter for extracting the effective loading history. Comparison of fatigue crack propagation curves obtained from the improved numerical simulations with the measurements which were conducted by Sumi (2010) is performed. These comparisons show the validity of the proposed procedure for extracting the effective loading history from the superposed loading history containing different frequencies. In addition, imperfection of the S-N curves approach, which corresponds to the combination of the linear cumulative damage law and the loading cycle count by the rain flow method, is conducted.

The Fatigue Crack and Delamination Behavior on the Fuselage-Wing Intersection Containing Variable Notches

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1540-1546 ◽  
Author(s):  
Sam Hong Song ◽  
Cheol Woong Kim
Keyword(s):  
Fatigue Crack ◽  
Stress Distribution ◽  
Crack Propagation ◽  
Circular Hole ◽  
Fatigue Crack Propagation ◽  
Aluminum Layer ◽  
Fiber Layer ◽  
Stress Criterion ◽  
Fatigue Crack Propagation Behavior ◽  
Propagation Behavior

The delamination and the fatigue crack propagation behavior in aramid fiber reinforced metal laminates(AFRMLs) containing a saw-cut and circular hole such as the fuselage-wing intersection was investigated. The fatigue crack propagation in aluminum layer is accompanied with the delamination between aluminum layer and fiber layer. The delamination deteriorates the fiber bridging mechanism in the crack tip of AFRMLs. Therefore, this study evaluates the stress distribution of AFRMLs containing a saw-cut and circular hole using the Average Stress Criterion (ASC) model. The delamination zone was observed by ultrasonic C-scan images. As the result of this study, in case of AFRMLs containing a saw-cut specimen. the fatigue crack propagation always occurred in aluminum layer and the delamination zone formed along the fatigue crack. However, in case of AFRMLs containing a circular hole specimen, the delamination zone was formed in two types. First, delamination zone was formed along the fatigue crack in aluminum layer. Second, delamination zone was formed without any fatigue crack around the circular hole. Consequently, delamination zone was formed dependently on the notch shape and the stress distribution.

Effect of Biaxial Static Loads on Fatigue Crack Propagation Behavior under Cyclic Tensile and Torsional Loading

2006 ◽  
Vol 321-323 ◽  
pp. 720-723
Author(s):  
Yong Hak Huh ◽  
Philip Park ◽  
Dong Jin Kim ◽  
Jun Hyub Park
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Growth Rates ◽  
Biaxial Loading ◽  
Torsional Loading ◽  
Static Loads ◽  
Fatigue Crack Propagation Behavior ◽  
Propagation Behavior ◽  
Crack Propagation Behavior

Fatigue crack propagation behavior under cyclic tensile or torsional loading with biaxial static loads has been investigated. Two different biaxial loading systems, i.e. cyclic tensile loading with static torsional load and cyclic torsional loading with static tensile load, were employed to thin-walled tubular specimens. The crack propagation was measured by two crack gages mounted near the notch and crack opening level was measured by unloading compliance method. The directions of the fatigue crack propagated under respective biaxial loading conditions were examined and the growth rates were evaluated by using several cyclic parameters, including equivalent stress intensity factor range, Keff, crack tip opening displacement range, CTD, minimum strain energy density factor range, Smin. Furthermore, the growth rates were evaluated by effective cyclic parameters considering crack closure. It was found that the biaxial static stress superimposed on the cyclic tensile or torsional loading tests has no influence on the propagation directions of the cracks. Furthermore, it was shown that the fatigue crack growth rates under biaixial faigue loading were well expressed by using the cyclic fatigue parameters, Keq,eff, CTDeff, Smin,eff considering crack closure effect.

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