The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
Q M Li - One of the best experts on this subject based on the ideXlab platform.
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appraisal of Pulse shaping technique in split hopkinson pressure bar tests for brittle materials
International Journal of Protective Structures, 2010Co-Authors: Y B Lu, Q M LiAbstract:Split Hopkinson pressure bar (SHPB) technique has been frequently used to measure the uniaxial compressive Stress-strain relation of brittle materials at intermediate strain-rates where Pulse-shaping technique is employed to improve the Stress uniformity and maintain a nearly constant strain-rate in the specimen during the effective loading period. This paper appraises the functions of the Pulse-shaping technique in SHPB tests of brittle samples based on numerical simulations of SHPB tests. It is shown that a proper Pulse-shaper can attenuate high frequency oscillations of the incident Pulse and increase the rise-time of the Pulse, resulting in the improvement of Stress equilibrium and uniformity along the axial direction of an SHPB specimen. However, it is found that the inertia-induced confinement in the radial direction of a brittle specimen is still significant even though the shaped incident Stress Pulse can generate a nearly flat plateau in the reflected Pulse in the SHPB test. It implies that the a...
Xiaofeng Li - One of the best experts on this subject based on the ideXlab platform.
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Stress Pulse attenuation in shear thickening fluid
Applied Physics Letters, 2013Co-Authors: Weifeng Jiang, Xinglong Gong, Shouhu Xuan, Wanquan Jiang, Fang Ye, Xiaofeng LiAbstract:The Stress Pulse attenuation of the 62 vol/vol. % dense silica particle-ethylene glycol suspension was investigated by using a modified spilt Hopkinson pressure bar. In comparison to the neat ethylene glycol solution, the transmission Pulse of the shear thickening is much weaker under the same impact condition. No energy loss is progressed for the neat ethylene glycol solution, thus it can be concluded that the energy dissipation behavior was happened in the silica particle based shear thickening fluid. In this work, the energy dissipation of the shear thickening fluid was reversible.
Vijay Gupta - One of the best experts on this subject based on the ideXlab platform.
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measurement of thin film interface toughness by using laser generated Stress Pulses
Journal of The Mechanics and Physics of Solids, 1998Co-Authors: A. N. Pronin, Vijay GuptaAbstract:Abstract A new technique to measure the toughness of interfaces is presented. In this experiment a laser-generated compressive Stress Pulse on the back surface of a substrate disc is made to propagate towards a thin film interface containing a population of well characterized microcracks. The compressive Stress Pulse reflects into a tensile Pulse from the coating's free surface and leads to the dynamic initiation of one of the cracks. The coating's free surface velocity at crack initiation is measured by using an optical interferometer, and related to the local energy release rate (equal to interface toughness) for a prescribed flaw geometry by using a numerical simulation based on dynamic fracture. Both penny-shaped and line interfacial microcracks were generated by combining photolithography and encouraging layer buckling from selected spots under the influence of their own residual compressive Stresses. The experimental strategy is demonstrated on interfaces between sapphire substrates with (0001) plane orientations and coatings of Al, Cr, Nb and Sb for which the interface toughnesses of 1.3, 0.8, 0.6 and 0.04 J/m 2 were obtained, respectively.
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Mechanisms and Quantification of Spalling Failure in Laminated Composites under Shock Loading
Journal of Composite Materials, 1996Co-Authors: Vijay Gupta, A Pronin, K. AnandAbstract:The free surface spalling phenomenon in 2D carbon/carbon (C/C) and carbon-polyimide (C/P) laminates was studied by subjecting them to laser-produced nano-second rise-time compressive Stress Pulses. The compression Pulse travels through the laminate normal to the plies and, upon reflection into a tension Pulse from the sample's front surface, leads to fiber/matrix debondings either in the bundles within a ply or at the interply interface. The Stress Pulse amplitude responsible for initiating such a damage was determined by recording the free surface velocity by an optical interferometer, and on the continuum scale, this is referred to as the effective interply strength. Since by employing a special specimen geometry we were able to determine the onset of such delaminations, its characterization in terms of an effective interply strength should be acceptable. Additional information on the attenuation and the dispersion characteristics associated with the propagation of such Stress Pulses was also obtained f...
Y B Lu - One of the best experts on this subject based on the ideXlab platform.
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appraisal of Pulse shaping technique in split hopkinson pressure bar tests for brittle materials
International Journal of Protective Structures, 2010Co-Authors: Y B Lu, Q M LiAbstract:Split Hopkinson pressure bar (SHPB) technique has been frequently used to measure the uniaxial compressive Stress-strain relation of brittle materials at intermediate strain-rates where Pulse-shaping technique is employed to improve the Stress uniformity and maintain a nearly constant strain-rate in the specimen during the effective loading period. This paper appraises the functions of the Pulse-shaping technique in SHPB tests of brittle samples based on numerical simulations of SHPB tests. It is shown that a proper Pulse-shaper can attenuate high frequency oscillations of the incident Pulse and increase the rise-time of the Pulse, resulting in the improvement of Stress equilibrium and uniformity along the axial direction of an SHPB specimen. However, it is found that the inertia-induced confinement in the radial direction of a brittle specimen is still significant even though the shaped incident Stress Pulse can generate a nearly flat plateau in the reflected Pulse in the SHPB test. It implies that the a...
Weifeng Jiang - One of the best experts on this subject based on the ideXlab platform.
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Stress Pulse attenuation in shear thickening fluid
Applied Physics Letters, 2013Co-Authors: Weifeng Jiang, Xinglong Gong, Shouhu Xuan, Wanquan Jiang, Fang Ye, Xiaofeng LiAbstract:The Stress Pulse attenuation of the 62 vol/vol. % dense silica particle-ethylene glycol suspension was investigated by using a modified spilt Hopkinson pressure bar. In comparison to the neat ethylene glycol solution, the transmission Pulse of the shear thickening is much weaker under the same impact condition. No energy loss is progressed for the neat ethylene glycol solution, thus it can be concluded that the energy dissipation behavior was happened in the silica particle based shear thickening fluid. In this work, the energy dissipation of the shear thickening fluid was reversible.
