The study of fatigue delamination growth in composite materials aims to develop a slow-growth approach for composite materials that would provide conservative and reliable results. The present work focuses on the study of the load ratio effect on fatigue crack growth at constant amplitude and on the effect of variable amplitude loading on crack propagation. With this in mind, a Crack Driving Force (CDF) is chosen to attempt to overlap delamination growth curves obtained from different load ratio values for mode I and mode II. It is shown that the CDF collects the effect of the load ratio on the crack growth curves and allows to build a crack growth master curve for mode I and II. Variable amplitude loads are then considered for delamination propagation in mode I. However, variable amplitude loads bring to light a load history effect during
fatigue crack growth that the CDF does not take into account.
#2Yi Sun(HIT: Harbin Institute of Technology)H-Index: 10
Last. Rinze Benedictus(TU Delft: Delft University of Technology)H-Index: 34
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This paper aims to investigate stress ratio effect on fibre bridging significance in mode I fatigue delamination growth of composite materials. Fatigue resistance curves (R-curves) of different stress ratios are determined and compared with the quasi-static R-curve. The fatigue R-curve of a high stress ratio is similar to the quasi-static results. However, fatigue resistance of a low stress ratio is smaller than quasi-static resistance. These indicate that fibre bridging significance is stress r...
Last. Chun H. Wang(RMIT: RMIT University)H-Index: 55
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Fatigue delamination growth in composite laminates is strongly influenced by mean loads or load ratios. Description of this behaviour currently relies on empirical curve fitting, which renders it difficult to predict fatigue lives of composite structures subjected to variable amplitude fatigue loading. This paper presents a new scaling parameter that is consistent with the similitude concept and incorporates the crack-tip shielding effects of fibre bridging under fatigue loading. Static and fati...
#1Liaojun Yao(TU Delft: Delft University of Technology)H-Index: 13
#2René Alderliesten(TU Delft: Delft University of Technology)H-Index: 31
Last. Rinze Benedictus(TU Delft: Delft University of Technology)H-Index: 34
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Abstract This paper provides a study on fatigue delamination growth in composite laminates using energy principles. Experimental data has been obtained from fatigue tests conducted on Double Cantilever Beam (DCB) specimens at various stress ratios. A concept of fatigue fracture toughness is proposed to interpret the stress ratio effect in crack growth. The fatigue fracture toughness is demonstrated to be interface configuration independent but significantly stress ratio dependent. An explanation...
A fatigue crack propagation test under mode II has been set up for unidirectional composite laminate characterization at high frequency. The specimen is clamped on a shaker and loaded on its first bending resonance mode. This dynamical test allows an accurate delamination extension monitoring based on the resonance frequency shift. Dynamical tests are conducted at 260 Hz and 400 Hz and their results are compared to those obtained with 10 Hz 3-ENF tests. Fatigue crack propagation results are pres...
Abstract The effects of crack closure and fibre bridging on delamination growth in carbon fibre/epoxy laminates under mode I fatigue loading have been experimentally investigated and are reported in this paper. The effect of crack closure has been investigated using a compliance based technique. The effect of fibre bridging has been investigated by comparing results of two sets of tests; one containing active fibre bridging while in the other fibre bridging was removed by cutting fibres during t...
#1Calvin Rans(TU Delft: Delft University of Technology)H-Index: 15
#2René Alderliesten(TU Delft: Delft University of Technology)H-Index: 31
Last. Rinze Benedictus(TU Delft: Delft University of Technology)H-Index: 34
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Use of the strain energy release rate for characterizing delamination growth in composite and bonded structures is now commonplace. Analogous to the use of the stress intensity factor range for fatigue crack growth in metals, the strain energy release rate range, defined as the arithmetic difference between maximum and minimum values, is often used to characterize fatigue delamination growth behaviour. The basis for similitude for these two parameters, however, is different and can lead to misin...
Abstract Interlaminar fracture toughness and delamination fatigue crack growth behavior were investigated for carbon fiber (CF)/epoxy laminates with the self-same epoxy interleaf. The matrix epoxy with a thickness of 50 μm was chosen as the interleaf material in order to clarify the effect of resin-rich layer thickness on the delamination fatigue crack growth behavior. Tests under mode I loading were carried out using double cantilever beam specimens. For tests under mode II loading, three-point...
#1Frédéric Lachaud(École nationale supérieure d'ingénieurs de constructions aéronautiques)H-Index: 15
#2B. Lorrain(École nationale supérieure d'ingénieurs de constructions aéronautiques)H-Index: 1
Last. R. Barriol(École nationale supérieure d'ingénieurs de constructions aéronautiques)H-Index: 1
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Abstract Experimental and numerical studies of delamination caused by local buckling have been carried out on thermoset and thermoplastic carbon-fibre composites. The propagation of delamination appears only after the appearance of macrocracks in the buckling plies. In the first part of this work, acoustic emission (Felicity ratio) is used to qualify damage accumulation before propagation of delamination. The second part deals with the determination of the initiation of delamination by two numer...
Last. P. K. Mallick(UM: University of Michigan)H-Index: 3
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Fatigue crack growth behavior of a randomly oriented short carbon fiber rein-forced polyether ether ketone (PEEK) composite is studied at four different load ratios. Based on the experimental data, a new fatigue crack growth model is proposed which accounts for crack growth throughout the entire fatigue cycle and not just at the maximum load. The proposed model involves a weighted averaging procedure and is found to fit the fatigue crack growth rates at all load ratios in a single power law equa...
Abstract The effects of positive stress ratios on the fatigue crack growth behavior of a forged, mill-annealed Ti-6Al-4V alloy (with a duplex α + β microstructure) are discussed. Differences between fatigue crack growth rates at low and high stress ratios are shown to be due largely to crack closure. A 1% offset procedure is shown to collapse “closure corrected” low stress ratio data with the “closure-free” high stress ratio data. A three parameter multiple regression model is developed for the ...
A new approach for simulating delamination initiation under cyclic loading is proposed. This approach is based on the hysteresis cohesive zone modeling and the gradual degradation of interface prop...
Abstract The stress ratio is commonly known to have an effect on the fatigue delamination growth (FDG) behavior of composite laminates. The crack closure phenomenon during delamination growth may change the value of stress ratio. Whether the stress ratio effect on the FDG behavior is resulted by the crack closure or not is investigated in this study and experimental evidences are presented in order to obtain a reliable conclusion. Using the quasi-static unloading approach, the crack closure load...
Last. Jianghong Xue(JNU: Jinan University)H-Index: 2
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Abstract In this paper, an extended first order shear deformation theory is proposed for Reissner-Mindlin laminated composite panels with internal delamination. The distinctive feature of the present theory is that a contact mechanism is involved in the governing equations based on FSDT by introducing a constitutive relation between the contact force and the transverse deflection and are expressed in terms of the displacements and the rotation functions. The proposed theory is applied to investi...
#1Babak Fazlali(IUST: Iran University of Science and Technology)H-Index: 3
#2Bijan Mohammadi(IUST: Iran University of Science and Technology)H-Index: 31
Abstract The off-axis fatigue behavior of unidirectional composites has been studied using an energy based model. The fatigue model is based on average stresses in fiber and matrix derived from a micromechanical approach. Different fatigue damage modes are identified on the basis of physical interpretation of the driving forces defined from Continuum Damage Mechanics. The model is able to distinguish between damage in fiber and matrix and predict the residual stiffness in transverse and longitud...