Measurement of the velocities of current-conducting shells with a sensor of the electromagnetic type

The methods used in practice for the acquisition and interpretation of experimental data pertaining to the resistance of materials to plastic-strain (shearstrength) are based on the concepts of the nature of motion of a material possessing strength and the features of high-rate deformation discussed in Chap. 1. These methods are briefly described below. Additional information on this topic is available to the reader in monographs [1-3], review [4], and the original papers cited in [1-4]. Comparison between the Shock Hugoniot and the Hydrostatic Compression IsothermGiven two assumptions: (1) material strength is isotropic, and (2) the difference between isothermal hydrostatic compression and the mean stress σ ii /3 is small, the dynamic yield strength is calculated to be the difference between the stress σ 1 on the elastic-plastic shock Hugoniot and the pressure P on the hydrostatic compression isotherm (given in terms of specific volume V (or strain ε)) as Y d = 3(σ 1 − P )/2. This approach to the estimation of Y d is limited to cases wherein the stresses σ 1 are relatively low, and the temperature rise during shock compression is modest (resulting in a thermal component of pressure that is low in comparison to the total pressure).For the aluminum alloy Al-2024, [5] recommends that for shock pressures in the 2.7 GPa ≤ σ 1 ≤ 9.4 GPa range, one should use the following relations for σ 1 (ε) (the normal stress component in a plane wave shock) and P (ε) (the hydrostatic compression) in calculations of the dynamic yield strength: σ 1 = 0.18 + 72.06ε − 347.1ε 2 (GPa); P = 75.9ε + 201ε 2 (GPa). This method for the evaluation of Y d , among other things, requires a highly accurate determination of the curves σ 1 (ε) and P (ε) since minor changes in ε can lead to significant changes in σ 1 and P .

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“…induced in a measuring coil with the conducting surface moving parallel to the coil plane (see [23,24] and Chap. The gauge measures E.M.F.…”

Section: Measurement Of Elastic Precursor Parametersmentioning

confidence: 99%

Dynamic Strength of Materials

Glushak¹,

Tyupanova²,

Bat'kov³

2006

Material Properties Under Intensive Dynamic Loading

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“…An electromagnetic sensor with a core made of ûçÑä35í5ÅÄ alloy and a coil with 30 turns of èùã-0.1 wire put on the core [15] was tested as a device for recording the motion of the tested obstacle. This sensor measured, in particular, the velocity of motion of the 15-mm-thick walls of a steel flask 150 mm in diameter.…”

mentioning

confidence: 99%

A Test Bench for the Shock Loading by an Electrical Explosion of Foils

2005

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Pulsed mechanical loads on objects are produced upon an electrical explosion of metal foils with an area of <400 cm 2 . A bank of 48 àä 100-0.4 ìïã4 capacitors is mounted in four metallic tanks with oil insulation and stores an energy of up to 96 kJ. Each two capacitors are switched by a thyratron and transfer a current along a cable line to a common electrical explosion unit. Twenty-four spark gaps operate with a time spread of ± 3 ns relative to the trigger pulse and have an electric strength margin of ~80% . The total inductance of the circuit is ~70 nH. The discharge current amplitude reaches 1.68 MA, and its oscillation quarter-period lasts ~1.8 µ s. Various designs for the electrical explosion unit, based on an aluminum foil 7 µ m thick, and methods for measuring the mechanical impulse values are described. The distribution of impulse over the foil area is controlled by the number of exploded foil layers. All of the test bench units can be transported and promptly put into operation at a new site.

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Measurement of the velocities of current-conducting shells with a sensor of the electromagnetic type

Cited by 2 publications

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Dynamic Strength of Materials

Dynamic Strength of Materials

A Test Bench for the Shock Loading by an Electrical Explosion of Foils

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