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Bhavani V Sankar – One of the best experts on this subject based on the ideXlab platform.
A Novel Method for Dynamic Short-Beam Shear Testing of 3D Woven CompositesExperimental Mechanics, 2012Co-Authors: T R Walter, Bhavani V Sankar, Ghatu Subhash, M. C. SongAbstract:
A new test method for performing dynamic short-Beam Shear tests using a momentum trapped Hopkinson pressure bar is proposed. Angle-interlock 3D woven composite specimens were tested under quasi-static and dynamic loading conditions to determine the effect of loading rate on damage evolution. The equilibrium condition in the composite specimen under dynamic loads was verified using finite element analysis of the experiment. A high speed camera was used to capture delamination initiation and propagation during both quasi-static and dynamic experiments. Analysis of the load-deflection curves and the high speed images revealed a good correlation between the modes of damage initiation and propagation with the features in the loading response. The apparent inter-laminar Shear strength and the bending stiffness increased with rate of loading. While the damage was observed to propagate at a relative steady rate during quasi-static loading, the high rate of energy input during dynamic loading resulted in a rapid propagation of damage and a subsequent loss of stiffness in the composite as noted in the load-deflection curve.
monotonic and cyclic short Beam Shear response of 3d woven compositesComposites Science and Technology, 2010Co-Authors: T R Walter, Ghatu Subhash, Bhavani V SankarAbstract:
Monotonic, multi-step and cyclic short Beam Shear tests were conducted on 2D and 3D woven composites. The test results were used to determine the effect of z-yarns on the inter-laminar Shear strength as well as the multi-loading behavior. The presence of z-yarns was found to affect not only the inter-laminar Shear strength of the composite but also the behavior of the composite beyond the elastic limit. Microscopic examination of the damaged specimens revealed large delamination cracks in 2D woven composites while delamination cracks were hindered by z-yarns in 3D composites. This crack arrest phenomena resulted in a reduction in inter-laminar crack lengths and a higher distribution of the micro-cracks throughout the 3D composite. The multi-step and cyclic loading tests are found to be useful in the monitoring of specimen behavior during short Beam Shear testing. The induced damage was quantified in terms of the loss of strength and stiffness during each loading cycle. It was found that while the 2D composites have higher damage resistance, the 3D composites have a higher damage tolerance.
Brian L. Wardle – One of the best experts on this subject based on the ideXlab platform.
Advanced carbon fiber composite out-of-autoclave laminate manufacture via nanostructured out-of-oven conductive curingComposites Science and Technology, 2018Co-Authors: Jeonyoon Lee, Xinchen Ni, Frederick Daso, Xianghui Xiao, Dale King, Jose Sánchez Gómez, Tamara Blanco Varela, Seth S. Kessler, Brian L. WardleAbstract:
Next-generation composite manufacturing processes are needed to overcome several limitations of conventional manufacturing processes (e.g., high energy consumption). Here we explore, via experiments and modeling, the characteristics of the newly developed out-of-oven (OoO) curing technique that cures a composite laminate via resistive heating of a carbon nanotube film. When compared to oven curing of an aerospace-grade out-of-autoclave (OoA) carbon fiber prepreg advanced composite laminate, the OoO curing reduces energy consumption by over two orders of magnitude (14 vs. 0.1 MJ). Thermophysical and mechanical tests including differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), short Beam Shear (SBS), and ex-situ and in-situ double-edge notch tension (DENT) indicate that the physical and mechanical properties of OoO-cured laminates are equivalent to those of oven-cured (baseline) laminates. In addition to energy savings, the OoO curing process has the potential to reduce part-to-part variations through improved spatiotemporal temperature control.
Damage Modelling of Thin-Ply Nano-reinforced Composite Laminates21st International Conference on Composite Materials (ICCM), 2017Co-Authors: Carolina Furtado, Xinchen Ni, Estelle Kalfon-cohen, Albertino Arteiro, Brian L. Wardle, Pedro P. Camanho, Roberto Frias, United States, Massachusetts AvenueAbstract:
© 2017 International Committee on Composite Materials. All rights reserved. Composite laminates composed of unidirectional carbon fibre-epoxy plies nano-stitched together with vertically aligned carbon nanotube arrays (A-CNT) have been recently developed. This technology has proven to improve both interlaminar and intralaminar composite strength and toughness. The consequences of nanostitching interfaces has mainly been studied by measuring the Interlaminar Shear strength (ILSS) of nanostitched interfaces and the respective baseline configurations of the same material system using short Beam Shear tests. In this study, short Beam Shear tests of unreinforced and nanostitched samples are modelled to better understand what are the effects of this type of nano-reinforcement on the mechanics of fracture of composite materials. Intralaminar damage is simulated using a continuum damage model previously proposed in the literature –. Interlaminar damage was simulated using a cohesive zone model implemented in ABAQUS. It was considered that the inclusion of carbon nanotubes in the interfaces leads to an increase of mode I and mode II fracture toughnesses. Since the enhancement factor was unknown, the fracture toughness of reinforced interfaces was inversely identified by analyzing the damage propagation and load displacement curves predicted by the models. The numerical results suggest that the nanostitched interfaces are ~5% or ~10-15% tougher than unreinforced interfaces depending on the carbon fibre-epoxy material system used.
W Karunasena – One of the best experts on this subject based on the ideXlab platform.
in plane Shear behaviour of fibre composite sandwich Beams using asymmetrical Beam Shear testConstruction and Building Materials, 2010Co-Authors: Allan Manalo, Thiru Aravinthan, W KarunasenaAbstract:
The in-plane Shear behaviour of a new generation composite sandwich Beam made up of glass fibre skins and modified phenolic core material was investigated to determine its application as Shear loading component in a structural Beam. Iosipescu Shear test was conducted to characterise the Shear properties of the fibre composite skins and the phenolic core material. The fibre composite sandwich Beams were then tested under asymmetrical Beam Shear to determine its behaviour under in-plane Shear loading. The results show that the in-plane Shear behaviour of the composite sandwich Beam is similar to that of the skins. A theoretical prediction of the in-plane Shear strength of the composite sandwich Beam was proposed and showed a good agreement with the experimental results. Based on the results of the study, the asymmetrical Shear test is recommended as a test method for determining the Shear properties of sandwich structures with high strength core materials.