Stress intensity factors as the fracture parameters for delamination crack growth in composite laminates

1998 ◽  
Vol 21 (1) ◽  
pp. 1-10 ◽  
Author(s):  
W. T. Chow ◽  
S. N. Atluri
Keyword(s):  
Stress Intensity ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Composite Laminates ◽  
Intensity Factors ◽  
Delamination Crack ◽  
Fracture Parameters

On the Characterization of Fatigue Crack Growth in a Plate With a Single-Sided Repair

2004 ◽  
Vol 126 (2) ◽  
pp. 192-198 ◽  
Author(s):  
C. N. Duong ◽  
C. H. Wang
Keyword(s):  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Load Path ◽  
Intensity Factors ◽  
Analytical Work ◽  
Out Of Plane ◽  
Plane Bending

An unsupported cracked plate repaired with a reinforcement bonded on one side may experience considerable out-of-plane bending due to the load-path eccentricity. This out-of-plane bending causes the stress intensity factor at the crack tip to vary significantly through the plate’s thickness with a maximum value attained at the un-patched side of the crack. Even though significant analytical work has been done in the past to evaluate these thickness-varying stress intensity factors, however, to the authors’ knowledge, little work has been done to characterize the fatigue crack growth in a plate with a single-sided repair. The purposes of the present work are to (i) assess the accuracy of the available analytical methods for predicting the stress intensity factors of the panels with a single-sided repair and more importantly, and (ii) characterize the fatigue crack growth in these panels, using test results generated recently under the Composite Repair of Aircraft Structures (CRAS) program.

On the Influence of the Corner Singularity on Kinking Mixed-Mode Crack Propagation

2007 ◽  
Vol 348-349 ◽  
pp. 585-588
Author(s):  
Henning Schütte ◽  
Kianoush Molla-Abbasi
Keyword(s):  
Stress Intensity ◽  
Crack Propagation ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Mixed Mode ◽  
Small Scale ◽  
Intensity Factors ◽  
Plastic Energy ◽  
Mixed Mode Crack ◽  
The Impact

The aim of the presentation is to highlight the influence of the kink, developing at the beginning of mixed-mode crack growth, on the propagation behavior of the crack. Le et al. [1] have shown that the variational principle of a body containing a crack results in the principle of maximum energy release rate incorporating the stress intensity factors of the kinked crack. Here the influence of the kink and the kinking angle, resulting in a singular field around the corner, on the crack growth is analyzed. The generalized stress intensity factors at the kinks corner are computed with the help of a FEM strategy. The influence of these on the T-stresses and the plastic energy dissipated at the kink is determined using a small scale yielding approach. The impact of these results on mixed-mode crack propagation is discussed.

Effect fracture resistance on retardation of crack growth

2015 ◽  
Vol 6 (4) ◽  
pp. 510-521
Author(s):  
Jirí Behal ◽  
Petr Homola ◽  
Roman Ružek
Keyword(s):  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Aluminium Alloy ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
High Stress ◽  
Intensity Factors ◽  
Content Type

Purpose – The prediction of fatigue crack growth behaviour is an important part of damage tolerance analyses. Recently, the author’s work has focused on evaluating the FASTRAN retardation model. This model is implemented in the AFGROW code, which allows different retardation models to be compared. The primary advantage of the model is that all input parameters, including those for an initial plane-strain state and its transition to a plane-stress-state, are objectively measured using standard middle-crack-tension M(T) specimens. The purpose of this paper is to evaluate the ability of the FASTRAN model to predict correct retardation effects due to high loading peaks that occur during variable amplitude loading in sequences representative of an aircraft service. Design/methodology/approach – This paper addresses pre-setting of the fracture toughness K R (based on J-integral J Q according to ASTM1820) in the FASTRAN retardation model. A set of experiments were performed using specimens made from a 7475-T7351 aluminium alloy plate. Loading sequences with peaks ordered in ascending-descending blocks were used. The effect of truncating and clipping selected load levels on crack propagation behaviour was evaluated using both experimental data and numerical analyses. The findings were supported by the results of a fractographic analysis. Findings – Fatigue crack propagation data defined using M(T) specimens made from Al 7475-T7351 alloy indicate the difficulty of evaluating the following two events simultaneously: fatigue crack increments after application of loads with maximum amplitudes that exceeded J Q and subcritical crack increments caused by loads at high stress intensity factors. An effect of overloading peaks with a maximum that exceeds J Q should be assessed using a special analysis beyond the scope of the FASTRAN retardation model. Originality/value – Measurements of fatigue crack growth on specimens made from 7475 T7351 aluminium alloy were carried out. The results indicated that simultaneously evaluating fatigue crack increments after application of the load amplitude above J Q and subcritical increments caused by the loads at high stress intensity factors is difficult. Experiments demonstrated that if the fatigue crack reaches a specific length, the maximal amplitude load induces considerable crack growth retardation.

scholarly journals Investigation of the Enhancement Interactions between Double Parallel Cracks on Fatigue Growth Behaviors

Materials ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 2952
Author(s):  
Zhichao Han ◽  
Caifu Qian ◽  
Huifang Li
Keyword(s):  
Stress Intensity ◽  
Crack Growth ◽  
Stress Intensity Factors ◽  
Growth Rates ◽  
Shielding Effect ◽  
Enhancement Effect ◽  
Intensity Factors ◽  
Single Crack ◽  
Parallel Cracks ◽  
Crack Growth Rates

In this paper, interactions of double parallel cracks were studied by performing experiments and numerical simulations. Fatigue crack propagation tests were carried out to measure crack growth rates in the specimens with double parallel cracks or a single crack. Finite element method was adopted to calculate stress intensity factors at the crack tips. Results show that the double parallel cracks at different positions present a shielding effect or enhancement effect on crack growth rates and stress intensity factors. When the double parallel cracks are offset, crack interactions mostly behave as enhancement effects. Empirical formulas were obtained to calculate the stress intensity factor at the “dangerous” crack tip of the double parallel cracks. By modifying the material parameters in Paris equation of the single crack, the double parallel cracks are simplified into a single crack with the same crack growth rates.

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