Fatigue damage growth rate in unidirectional composites in flexural loading

1985 ◽  
Vol 4 (2) ◽  
pp. 197-199 ◽  
Author(s):  
Golam M. Newaz
Author(s):  
Bent F. Sørensen ◽  
Stergios Goutianos ◽  
Lars P. Mikkelsen ◽  
Søren Fæster

2015 ◽  
Vol 19 (5) ◽  
pp. 563-570 ◽  
Author(s):  
Ridha Hambli ◽  
Sana Frikha ◽  
Hechmi Toumi ◽  
João Manuel R. S. Tavares

Author(s):  
Wenfeng Tu ◽  
Xiaogui Wang ◽  
Zengliang Gao

The experiments of mixed Mode I-II fatigue crack growth with altering loading direction were conducted with compact specimens made of 16MnR steel. The specimens were tested under three loading steps. When the crack reached a certain length in the first step, the loading direction was switched to a certain angle. Finally, the loading direction was returned to the original orientation. The crack grow direction had a tendency perpendicular to the loading axis. Right after the loading direction was changed, the crack growth rate was retarded. A new approach developed was used to predict the crack growth behavior. The elastic-plastic stress analysis was performed using the finite element method with the implementation of a cyclic plasticity model. Based on the stress-strain response, fatigue damage near the crack tip was determined by a multi-axial fatigue criterion. Both the crack growth rate and cracking direction were obtained according to the maximum fatigue damage distribution on the critical material plane. The predictions for the crack growth behavior including the crack growth rate and crack growth path were in agreement with the experimental data.


Author(s):  
Koji Miyoshi ◽  
Masayuki Kamaya

Abstract Mixing flow causes fluid temperature fluctuations near the pipe walls and may result in fatigue crack initiation. The authors have previously reported the loading sequence effect on thermal fatigue in a mixing tee. The fatigue damage around the hot spot, which was heated by the hot jet flow from the branch pipe, obtained by Miner’s rule was less than 1.0. Since the strain around the hot spot had waveforms with periodic overload, the loading sequence with periodic overload caused reduction of the fatigue life around the hot spot. In this study, the effect of a single overload on the fatigue crack growth rate was investigated in order to clarify the reduction of the fatigue life at the mixing tee due to strain with periodic overload. In addition, the prediction method of the fatigue life for the variable thermal strain at the mixing tee was discussed. It was shown the crack growth rate increased after an overload for both cases of tensile and compressive overloads. The effective strain amplitude increased after the application of a single overload. The fatigue life curve was modified by considering the increment of the effective strain range. The fatigue damage recalculated using the modified fatigue life curve was larger than 1.0 except in a few cases. The fatigue life could be assessed conservatively for variable strain at the mixing tee using the developed fatigue curve and Miner’s rule.


2008 ◽  
Vol 44-46 ◽  
pp. 111-118
Author(s):  
Wen Feng Tu ◽  
Xiao Gui Wang ◽  
Zeng Liang Gao

Based on two different cyclic plasticity models, fatigue crack growth for 16MnR steel specimens is simulated by using the same multi-axial fatigue damage criterion. The first plasticity model is the Jiang and Sehitoglu model and the second plasticity model is the simple nonlinear kinematic hardening model. The elastic-plastic stress-strain field near the crack tip is obtained respectively by using the two plasticity models. According to the same fatigue criterion, different fatigue damage near the crack tip is determined on the basis of stress-strain responses. The first plasticity model can accurately capture cyclic plasticity deformation behavior and predictions of fatigue crack growth rate are in agreement with the experimental results. However, lots of material constants in the model need to be fitted and more experimental tests should be conducted. The second plasticity model is very simple. The parameters of the model can be acquired easily by uniaxial fatigue tests. Compared with experimental data, the prediction results of fatigue crack growth rate lead to some errors by adopting the second plasticity model.


2015 ◽  
Author(s):  
Joseph N. Zalameda ◽  
Eric R. Burke ◽  
Michael R. Horne ◽  
James B. Bly

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