He even had some prescient hunches about the mechanism of blast's effects: the compression wave, the concussion and the toxic gases.
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A tensile wave was created by impacting the weight bar with a ram and having the initial compression wave reflect as a tensile wave off the free endJ. Harding, E. O. Wood and J. D. Campbell, "Tensile Testing of Materials at Impact Rates of Strain", Journal of Mechanical Engineering Science 2 (1960) 88–96 Another breakthrough in the SHPB design was done by Nichols who used a typical compression setup and threaded metallic specimens on both the incident and transmission ends, while placing a composite collar over the specimen. The specimen had a snug fit on the incident and transmission side in order to bypass an initial compression wave. Nichols setup would create an initial compression wave by an impact in the incident end with a striker, but when the compression wave reached the specimen, the threads would not be loaded.
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P-wave refraction evaluates the compression wave generated by the seismic source located at a known distance from the array. The wave is generated by vertically striking a striker plate with a sledgehammer, shooting a seismic shotgun into the ground, or detonating an explosive charge in the ground. Since the compression wave is the fastest of the seismic waves, it is sometimes referred to as the primary wave and is usually more-readily identifiable within the seismic recording as compared to the other seismic waves.
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However, in a wide variety of physical situations, a compression wave inclined at an angle to the flow occurs. Such a wave is called an oblique shock. Indeed, all naturally occurring shocks in external flows are oblique.
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Their explanation for fast emission propagation is the dual of the active traveling wave, the active compression wave. Active compression waves were proposed as early as 1980 by WilsonWilson, J.P., 1980. Evidence for a cochlear origin for acoustic re-emissions, threshold fine-structure and tonal tinnitus.
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U_L < U_R , and that the parameter \eta , is used to modulate dissipation when the fluid is under the action of a compression wave, i.e. U_L \geq U_R . Numerical experiments found the \eta = 3 is generally effective. Also note that the dissipation introduced by the intermediate velocity is not limited.
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The compression wave would ideally pass through the composite collar and then reflect off the free end in tension. The tensile wave would then pull on the specimen. The next loading method was revolutionized by Ogawa in 1984. A hollow striker was used to impact a flange that is threaded to end on an incident bar.
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It is caused mainly from isentropic heating of the air molecules within the compression wave. Friction based entropy increases of the molecules within the wave also account for some heating. The distance from the shock wave to the stagnation point on the entry vehicle's leading edge is called shock wave stand off. An approximate rule of thumb for shock wave standoff distance is 0.14 times the nose radius.
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The resonance properties of a cylinder may be understood by considering the behavior of a sound wave in air. Sound travels as a longitudinal compression wave, causing air molecules to move back and forth along the direction of travel. Within a tube, a standing wave is formed, whose wavelength depends on the length of the tube. At the closed end of the tube, air molecules cannot move much, so this end of the tube is a displacement node in the standing wave.
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S-wave refraction evaluates the shear wave generated by the seismic source located at a known distance from the array. The wave is generated by horizontally striking an object on the ground surface to induce the shear wave. Since the shear wave is the second fastest wave, it is sometimes referred to as the secondary wave. When compared to the compression wave, the shear wave is approximately one-half (but may vary significantly from this estimate) the velocity depending on the medium.
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When played loudly, the reed can spend up to 50% of the time shut. The 'puff of air' or compression wave (around 3% greater pressure than the surrounding air) travels down the cylindrical tube and escapes at the point where the tube opens out. This is either at the closest open hole or at the end of the tube (see diagram: image 1). # More than a 'neutral' amount of air escapes from the instrument, which creates a slight vacuum or rarefaction in the clarinet tube. This rarefaction wave travels back up the tube (image 2).
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The impact produces a compression wave that propagates through the intermediate balls. Any efficiently elastic material such as steel does this, as long as the kinetic energy is temporarily stored as potential energy in the compression of the material rather than being lost as heat. There are slight movements in all the balls after the initial strike but the last ball receives most of the initial energy from the impact of the first ball. When two (or three) balls are dropped, the two (or three) balls on the opposite side swing out.
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In a solid, the amount of compression generally depends on the direction x, and the material may be under compression along some directions but under traction along others. If the stress vector is purely compressive and has the same magnitude for all directions, the material is said to be under isotropic or hydrostatic compression at that point. This is the only type of static compression that liquids and gases can bear. In a mechanical longitudinal wave, or compression wave, the medium is displaced in the wave's direction, resulting in areas of compression and rarefaction.
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In addition to the mechanical and electronic cones, a variety of other CPT-deployed tools have been developed over the years to provide additional subsurface information. One common tool advanced during CPT testing is a geophone set to gather seismic shear wave and compression wave velocities. This data helps determine the shear modulus and Poisson's ratio at intervals through the soil column for soil liquefaction analysis and low-strain soil strength analysis. Engineers use the shear wave velocity and shear modulus to determine the soil's behavior under low-strain and vibratory loads.
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The shock Hugoniot describes the locus of all possible thermodynamic states a material can exist in behind a shock, projected onto a two dimensional state-state plane. It is therefore a set of equilibrium states and does not specifically represent the path through which a material undergoes transformation. Weak shocks are isentropic and that the isentrope represents the path through which the material is loaded from the initial to final states by a compression wave with converging characteristics. In the case of weak shocks, the Hugoniot will therefore fall directly on the isentrope and can be used directly as the equivalent path.
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An elastically deformable mass deforms under an applied force (or acceleration); the deformation is a function of its stiffness and the magnitude of force. If the change in force is slow, the jerk is small, and the propagation of deformation is considered instantaneous as compared to the change in acceleration. The distorted body acts as if it were in a quasi-static regime, and only a changing force (non- zero jerk) can cause propagation of mechanical waves (or electromagnetic waves for a charged particle); therefore, for nonzero-to-high jerk, a shock wave and its propagation through the body should be considered. The propagation of deformation is shown in the graphic "Compression wave patterns" as a compressional plane wave through an elastically deformable material.
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HMS New Zealands 'X' turret during the Battle of Jutland on display at the Torpedo Bay Navy Museum in Auckland. Caption reads, "The chunk of armour plating you see here was gouged out of X turret by a German shell." In anti-tank warfare, spalling through mechanical stress is an intended effect of high-explosive squash head (HESH) anti-tank shells and many other munitions which may not be powerful enough to pierce the armor of a target. The relatively soft warhead, containing or made of plastic explosive, flattens against the armor plating on tanks and other armored fighting vehicles (AFVs) and explodes, creating a shock wave that travels through the armor as a compression wave and is reflected at the free surface as a tensile wave breaking (tensile stress/strain fracture) the metal on the inside.
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