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Experiments are described in which large tensile pulses are propagated along stretched rubber bands. It is shown that if the pulse is sufficiently large in amplitude it develops a tensile shock front as it progresses along the band. (Author)
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This article describes the results of shock wave experiments performed on a heavy tungsten alloy containing W, Ni, and Fe in the ratio of 92. 85:4.9:2.25 by weight. These experiments provide information about the shear strength un...
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This article describes the results of shock wave experiments performed on a heavy tungsten alloy containing W, Ni, and Fe in the ratio of 92. 85:4.9:2.25 by weight. These experiments provide information about the shear strength under compression and tensile strength, as measured by the spall threshold, of this alloy to 24 GPa. The results of these experiments show that: (i) the magnitude of its Hugoniot elastic limit (HEL) is 2.76 + 0.26 GPa; (ii) this alloy deforms plastically above its HEL and thus retains its shear strength to 24 GPa; (iii) the spall strength of the alloy is found to be 1.9 i 0.4 GPa and is independent of the impact stress and duration of the shock compression pulse; and (iv) the tensile impedance of the alloy, determined from a new experiment designed to measure this impedance, is 68 + 10 Gg(m2S).
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A recent advanced model for the shock consolidation of powders predicts, for a powder given distension, the regimes of shock pressure and shock duration expected to yield fully densified compacts of near optimum strength. The mode...
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A recent advanced model for the shock consolidation of powders predicts, for a powder given distension, the regimes of shock pressure and shock duration expected to yield fully densified compacts of near optimum strength. The model is evaluated in terms of UTS measurements in compacts of rapidly solidified powders of AISI 9310 alloy, shocked to initial shock pressures between 3.6 and 17.9 GPa and to shock durations between 0.23 and 2.1 mu s. We find that in powders of distention 1.7, shock durations > 1 mu s are required at 10 GPa to properly solidify the melt. (ERA citation 09:004939)
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For the computer modeling of the in-situ fracturing of oil shales for retorting, the dynamic properties of oil shale need to be determined. Elastic properties and dynamic tensile strength were measured on shales from the Anvil Poi...
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For the computer modeling of the in-situ fracturing of oil shales for retorting, the dynamic properties of oil shale need to be determined. Elastic properties and dynamic tensile strength were measured on shales from the Anvil Points Mine. The response to plane stress impulses was measured. 7 figures. (ERA citation 02:058432)
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The traditional source model for long-period seismic waves from nuclear explosions consists of a monopole releasing tectonic strain. Tectonic release has been studied since the 1960's, and numerous studies have shown that linear s...
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The traditional source model for long-period seismic waves from nuclear explosions consists of a monopole releasing tectonic strain. Tectonic release has been studied since the 1960's, and numerous studies have shown that linear superposition of monopole + double-couple sources can explain many observations of Rayleigh and Love waves. Free surface interactions and the dynamics of shock-wave rebound are responsible for modes of tensile failure which can also lead to permanent deformations affecting long-period excitation. Indeed, the vast majority of nuclear explosions worldwide were conducted under containment conditions that facilitated shock-induced, deep-seated tensile failure. A new source model, which is a superposition of monopole + tectonic release + shock-induced tensile failure, is proposed, the latter source represented by a compensated-linear-vector dipole (CLVD) with vertical axis of symmetry. This CLVD source does not excite Love waves. I draw upon the Toksoz-Kehrer (1972) model for tectonic release where F is an index measuring long-period source strength of the release relative to monopole moment MI. A new index K, analogous to F, is introduced, providing a relative measure of MCLVD, the source strength of tensile failure. MCLVD vanishes for K = 1, and is > 0 in the case of extensional deformation along the vertical axis, e.g., K > 1. Rayleigh waves from the CLVD destructively interfere with waves from the monopole, and polarity reversals occur on all azimuths for K > approximately 3 in Poisson media. Most Nevada Test Site (NTS) observations support approximately 1.
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The microhardness, ultimate tensile strength, and elastic modulus of 44 to 74 mu m AISI 9310 rapidly solidified powder, consolidated by shock waves with energies varying from 94 to 770 kJ/kg and a shock duration of 2 to 3 mu s, ar...
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The microhardness, ultimate tensile strength, and elastic modulus of 44 to 74 mu m AISI 9310 rapidly solidified powder, consolidated by shock waves with energies varying from 94 to 770 kJ/kg and a shock duration of 2 to 3 mu s, are presented. The compacts produced have a variation in diamond pyramid hardness from 390 to 510, in strength from 0 to 1.4 GPa, and in elastic modulus from 66 to 181 GPa. The hardness and strength reach a maximum at 500 kJ/kg shock energy. The strength and elastic modulus results imply that 800 kJ/kg shock energy produces complete interparticle bonding. (ERA citation 09:028733)
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Experimental loading techniques are described which allow a detailed study of material response under more-general loading conditions than achieved in conventional uniaxial strain experiments. These techniques allow the use of smo...
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Experimental loading techniques are described which allow a detailed study of material response under more-general loading conditions than achieved in conventional uniaxial strain experiments. These techniques allow the use of smooth bore guns to generate well-controlled one-dimensional combined pressure-shear waves in flat plates. A velocity-interferometer technique used to determine both longitudinal and shear particle velocity at the target-free surface is also described. (ERA citation 08:012882)
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In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of late...
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In this report, we examine the propagation of tensile waves of finite deformation in rubbers through experiments and analysis. Attention is focused on the propagation of one-dimensional dispersive and shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in the rubber strips. Analysis of the response through the theory of finite waves and quantitative matching between the experimental observations and analytical predictions was used to determine an appropriate instantaneous elastic response for the rubbers. This analysis also yields the tensile shock adiabat for rubber. Dispersive waves as well as shock waves are also observed in free-retraction experiments; these are used to quantify hysteretic effects in rubber.
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A method for severing or weakening materials is discussed. Explosive cords are placed in grooves on the upper surface of the material to be severed or weakened. The explosive cords are initiated simultaneously to introduce explosi...
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A method for severing or weakening materials is discussed. Explosive cords are placed in grooves on the upper surface of the material to be severed or weakened. The explosive cords are initiated simultaneously to introduce explosive shock waves into the material. These shock waves progress toward the centerline between the explosive cords and the lower surface of the material. Intersecting and reflected waves produce a rarefaction zone on the centerline to fail the material in tension. A groove may also be cut in the lower surface of the material to aid in severing or weakening the material.
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This program was conducted to assess the effects of shock wave thermomechanical processing on nickel-base (Ni) gas turbine disks. In particular, the peak pressure limit on shaped subscale turbine disks was determined based on allo...
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This program was conducted to assess the effects of shock wave thermomechanical processing on nickel-base (Ni) gas turbine disks. In particular, the peak pressure limit on shaped subscale turbine disks was determined based on allowable permanent deformation and fracture. Using maximum pressure and selected shock/heat-treat schedules, the effect on mechanical properties was determined with results indicating an enhancement of strength, particularly the yield strength, with only a slight decrease in ductility. In general, low-cycle fatigue (LCF) life was not significantly affected, however, two samples tested showed a 3X improvement in life. In addition, two shock/heat-treat schedules were found to be extremely beneficial and will be investigated further. (Author)
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