Effect of Interface Damage on Fatigue Crack Growth for SiC Fiber-Reinforced Ti-15-3 Matrix Composite

2000 ◽  
Author(s):  
Yoshihisa Tanaka ◽  
Yu-Fu Liu ◽  
Chitoshi Masuda
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Crack Opening Displacement ◽  
Test Temperature ◽  
Wear Behavior ◽  
Crack Opening ◽  
Opening Displacement ◽  
Crack Wake

Abstract The fatigue crack growth behavior in SiC (SCS-6) fiber reinforced Ti-15-3 matrix alloy composite subjected to a constant tension-tension loading mode was studied using single edge specimen in 2 × 10−3 Pa vacuum at 293 and 823K, with a frequency of 2 Hz, and a stress ratio of R = 0.1. Direct measurement of the fatigue crack length, and the crack opening displacement along the crack wake during the test were carried out by scanning electron microscope (SEM). The increase in the test temperature was found to lead to a decrease in the fatigue crack growth rate. The degradation of bridging fibers in the crack wake was severe for T = 293K, and this behavior was dependent of the test temperature. Fine particle-like debris was found on the fracture surface in the region of crack propagation in specimens tested at T = 823K. This is thought to be caused by the interface wear behavior. The crack opening displacement along the crack wake tested at T = 823K decreased with increasing crack length, and this tendency is dependent on the applied stress range. The associated increase in the crack tip shielding is explained on the basis of the crack closure due to the matrix relaxation by fatigue creep and the interface wear behavior.

Crack opening displacement and the rate of fatigue crack growth

1972 ◽  
Vol 8 (2) ◽  
pp. 209-219 ◽  
Author(s):  
R. J. Donahue ◽  
H. McI Clark ◽  
P. Atanmo ◽  
R. Kumble ◽  
A. J. McEvily
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Opening Displacement ◽  
Crack Opening ◽  
Opening Displacement

Crack opening displacement and the rate of fatigue crack growth

1972 ◽  
Vol 8 (2) ◽  
Author(s):  
R.J. Donahue ◽  
H.McI. Clark ◽  
P. Atanmo ◽  
R. Kumble ◽  
A.J. McEvily
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Opening Displacement ◽  
Crack Opening ◽  
Opening Displacement

Characterizing Fatigue Crack Closure by Numerical Analysis

2008 ◽  
Vol 33-37 ◽  
pp. 273-278 ◽  
Author(s):  
Ya Zhi Li ◽  
Jing He ◽  
Zi Peng Zhang ◽  
Liang Wang
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Numerical Analysis ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Crack Closure ◽  
Crack Opening ◽  
Crack Tip ◽  
Fatigue Crack Closure

The crack closure phenomenon has attracted great attention in the prediction of fatigue crack growth. The finite element analysis of fatigue crack growth has been conducted by many researchers mainly emphasized on the technique implementation of the simulation. In this paper the behavior of plasticity induced fatigue crack closure was analyzed by the elastic-plastic finite element method for middle crack tension (MT) specimen. The material was assumed as linear-kinematic hardening. The crack growth was simulated by releasing the “bonded” node pairs ahead of crack tip in stepwise. The calculations focused on the effects of load cases and crack length on crack opening/closure levels. For constant amplitude cyclic loadings with different load ratios, the crack opening/closure levels increases for a while and then decreases continuously, with the increase of crack length. For the loadings with invariable maximum stress intensity factors (briefly the constant-K loading), however, the crack tip plastic zone sizes at different crack lengths remain unchanged and the crack opening and closing load levels normalized by the maximum load levels keep constants as well. The results indicate that the crack length does not affect the relative opening and closure levels and numerical analysis for the constant-K loading case should play a key role in characterizing the fatigue crack growth behavior.

Numerical analysis of fatigue crack growth using a plastically dissipated energy factor based model

2021 ◽  
pp. 095440622110478
Author(s):  
Jie Wang ◽  
Wei Jiang
Keyword(s):  
Numerical Simulation ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Crack Opening ◽  
Dissipated Energy ◽  
Plastic Behavior ◽  
Opening Displacement ◽  
Load Range ◽  
Simulation Scheme

The investigation of fatigue crack growth (FCG) behavior may contribute to the assessment of damage tolerance of components. To study the FCG behavior considering the elastic–plastic behavior at the crack tip, a numerical simulation scheme based on compact tension (CT) specimen is developed. Also, an effective plastically dissipated energy (PDE) factor composed of maximum PDE ([Formula: see text]) and PDE range ([Formula: see text]) is proposed to establish the expression for evaluating the FCG rate. The simulation results show good agreement with the results of test under same load conditions. Also, the mesh sensitivity analysis and the comparison with test results confirm the validation of proposed model. Based on the proposed numerical simulation scheme, the FCG behavior is studied by analyzing the influence of plastic wake, mean load, load range, overload, underload, load sequence, and cyclic compression load on FCG from the perspective of crack driving force, FCG rate, and crack opening displacement (COD). It is found from the analysis results that the developed numerical simulation scheme can consider the load history effect and crack closure effect. The mechanisms of these factors on the influence of FCG rate are analyzed in detail.

scholarly journals Crack-Length Estimation for Structural Health Monitoring Using the High-Frequency Resonances Excited by the Energy Release during Fatigue-Crack Growth

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4221
Author(s):  
Roshan Joseph ◽  
Hanfei Mei ◽  
Asaad Migot ◽  
Victor Giurgiutiu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Length ◽  
Crack Growth ◽  
Health Monitoring ◽  
Acoustic Waves ◽  
High Frequency ◽  
Fem Analysis ◽  
Signal Frequency ◽  
Propagation Pattern

Acoustic waves are widely used in structural health monitoring (SHM) for detecting fatigue cracking. The strain energy released when a fatigue crack advances has the effect of exciting acoustic waves, which travel through the structures and are picked up by the sensors. Piezoelectric wafer active sensors (PWAS) can effectively sense acoustic waves due to fatigue-crack growth. Conventional acoustic-wave passive SHM, which relies on counting the number of acoustic events, cannot precisely estimate the crack length. In the present research, a novel method for estimating the crack length was proposed based on the high-frequency resonances excited in the crack by the energy released when a crack advances. In this method, a PWAS sensor was used to sense the acoustic wave signal and predict the length of the crack that generated the acoustic event. First, FEM analysis was undertaken of acoustic waves generated due to a fatigue-crack growth event on an aluminum-2024 plate. The FEM analysis was used to predict the wave propagation pattern and the acoustic signal received by the PWAS mounted at a distance of 25 mm from the crack. The analysis was carried out for crack lengths of 4 and 8 mm. The presence of the crack produced scattering of the waves generated at the crack tip; this phenomenon was observable in the wave propagation pattern and in the acoustic signals recorded at the PWAS. A study of the signal frequency spectrum revealed peaks and valleys in the spectrum that changed in frequency and amplitude as the crack length was changed from 4 to 8 mm. The number of peaks and valleys was observed to increase as the crack length increased. We suggest this peak–valley pattern in the signal frequency spectrum can be used to determine the crack length from the acoustic signal alone. An experimental investigation was performed to record the acoustic signals in crack lengths of 4 and 8 mm, and the results were found to match well with the FEM predictions.

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