Papers by Keyword: Delamination

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Authors: S. Mohammadi, S. Forouzan-Sepehr
Authors: Irene Guiamatsia, Giang Dinh Nguyen
Abstract: Failure develops and propagates through a structure via a complex sequence of competing micro-mechanisms occurring simultaneously. While the active mechanism of surface debonding is the source of loss of stiffness and cohesion, friction between cracked surfaces, upon their closure, acts as a passive dissipation mechanism behind the quasi-brittleness and hence can increase the toughness of the material under favorable loading conditions. In order to numerically study damage propagation, the constitutive response must be able to faithfully capture, both qualitatively and quantitatively, one of the signature characteristic of failure: the energy dissipation. In this paper, we present an interface decohesive model for discrete fracture that is able to capture the apparent enhancement of interfacial properties that is observed when transverse compressive loads are applied. The model allows to seamlessly account for the additional frictional dissipation that occurs when the loading regime involves transverse compression, whether during debonding or after full delamination. This constitutive model is then used to successfully predict the response of realistic engineering structures under generalized loading conditions as demonstrated with the numerical simulation of a fiber push-out test.
Authors: Badrinath Veluri, Henrik Myhre Jensen
Abstract: Corner cracks under steady-state delamination were investigated. The fracture mechanics parameters that include the strain energy release rate and the three-dimensional mode-mixity along the interface crack front are estimated. A numerical approach was then applied for coupling the far field solutions based on the Finite Element Method to the near field (crack tip) solutions based on the J-integral methodology. A quantitative approach was formulated based on the finite element method with iterative adjustment of the crack front nodal coordinates to estimate the critical delamination stresses as a function of the fracture criterion and corner angles.
Authors: Young Shin Lee, Hyun Soo Kim, Young Jin Choi, Jae Hoon Kim
Abstract: The laminated composite structures applied to the wing and the speed brake of an aircraft or the turbine blade of a compressor. These structures may be impacted by birds and hails during operation. They may also be impacted by drop of a tool during manufacture or repair. Unlike high velocity impact damage, which can be easily found by the naked eye, the damage due to low velocity impact may be difficult to detect. Damage which is not detected may cause failure of a structure and result in damage propagation. Growth of damage means reduction of stiffness on the structure. So, exact prediction of damage caused by a low velocity impact is very important in order to guard against sudden failure of the structure. In this study, modified delamination failure criterion has suggested in order to predict the failure behavior of a composite plate subjected to low-velocity impact. The criterion includes the assumption which is matrix cracking mode causes delamination failure. Predicted damage using supposed delamination criterion is similar to experiment results.
Authors: Xu Wang, Yan Li He, Jing Yi Wang
Abstract: In this paper,according to the shell theory , model are developed to predict delamination damage in the drilling process. Finally, we will get theoretical delamination factor and complete the prediction of the delamination damage area. The known references didn’t find similar model of predicting delamination damage. Therefore, it is new method. With the drilling process experimental contrast,the model is more effective for the prediction of delamination of the carbon fiber composite materials.
Authors: Xiao Yuan Wang, Ya Bin Yan
Abstract: A nanocantilever bending method is developed to investigate the interface cracking in multilayered nanoscale materials basing on the technology of the focused ion beam (FIB) and the transmission electron microscopy (TEM). With FIB, a nanocantilever specimen consisting of 20-nm-thick copper (Cu) layer and 500-nm-thick silicon nitride (SiN) layer on a silicon (Si) substrate is fabricated from a macroscale multi-layered material (Si/Cu/SiN) with the proposed method. By using a minute loading apparatus, the loading experiment is conducted in TEM, and the crack initiation at the edge of Cu/Si interface in different specimens is in situ observed. The critical stress fields at crack initiation are analyzed with the finite element method, and both normal and shear stresses concentrate at the region of 100 nm from the interface edge in all specimens. In addition, the normal stress is much larger than the shear one. A close observation on stress fields shows that the normal stress field at the area 20 nm–30 nm away from interface edge produces the local criterion for crack initiation at the edge of Cu/Si interface in nanoscale components.
Authors: Omar Bacarreza, M.H. Aliabadi
Abstract: A novel methodology for analysis of fatigue delamination growth, capable of dealing with complex delamination shapes and mixed-modes in a computationally efficient way, is proposed. It combines the VCCT to find the energy release rates and the XFEM to update the geometry during the progressive failure, thus making it very robust and computationally efficient. The methodology is demonstrated at coupon level.
Authors: Jiang Tao Ruan, Shi Bin Wang, Jing Wei Tong, Min Shen, Francesco Aymerich, Pierluigi Priolo
Abstract: The results on a numerical and experimental study of graphite/epoxy composite plates [03/903]S are presented. Each specimen was firstly impacted by the low velocity with different energy level. Compression experiment based on carrier electronic speckle pattern interferometry (carrier-ESPI) is made for the post-impact composite plate. The finite element method (FEM) is used to gain further understanding of the deformation behavior of impacted specimens. The compressive deformation of various delaminated composite plates are analyzed with software ANSYS to see that the impact parameters and delamination damage data, such as impact energy, maximum impact force and delamination area, affect the deformation fields. In addition, the comparisons between the finite element results and experimental measurements are considered under different compression loads.
Authors: Zhong Hai Xu, Rong Guo Wang, Wen Bo Liu, Cheng Qin Dai, Lu Zhang, Xiao Dong He
Abstract: In this paper, we predict the delamination buckling behavior in slender laminated composite with embedded delamination under compressive load by using the finite element method (FEM). For the different delamination size and depth position, we illustrate the various parameters effects on buckling behavior.
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