Three Low-pressure Spall Thresholds in Copper

Smith, J.H.

doi:10.1520/stp42034s

Cited by 12 publications

(5 citation statements)

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“…that several thresholds of spalling (incipient fracture, intermediate stage, and the main crack formation) can be observed in samples after testing with load pulses of various durations [1]. The existence of several thresholds is a consequence of evolution of the fracture process in time.…”

Section: Metals and Alloysmentioning

confidence: 93%

Spallation in Solids Under Shock-Wave Loading: Analysis of Dynamic Flow, Methodology of Measurements, and Constitutive Factors

Kanel¹,

Разоренов²,

Уткин³

1996

High-Pressure Shock Compression of Solids II

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Spallation occurs when two rarefaction waves interact in a body and produce enough tension to fracture it. The principal content of investigations of spall phenomena that have been conducted are: (i) metallographic examination of the spall zone in recovered samples to obtain the correlation of the degree of damage with various features of the stress history [1-3] and (ii) instrumental measurement of resistance to dynamic fracture [4][5][6]. In the former case the result is information about the ability of the material to withstand shock loading, about the mechanism of nucleation and development of micro-cracks or pores, and statistical description of these processes. Dynamic measurements (free-surface velocity profiles or pressure on the interface with a soft material) during the shock-wave loading give the most correct data about stresses present during the spall process. The theoretical background of these measurements is discussed in Section 1.2 of this chapter.The damage rate, which is approximately equal to the product of concentration of damage nucleation sites and the average growth rate of damage at the sites, cannot be arbitrarily large. Under conditions of rapid dynamic loading, fracture is an essentially rate-dependent process. As a result, the spall strength value is not a material constant. It is more correct to speak about the resistance to fracture as a function of strain rate and other parameters of state. Since the fracture evolves over a period of time comparable with the duration of a shock wave experiment, we have to identify the stage of fracture which corresponds to the fracturing stress as this stress is determined by dynamic measurements. The acoustic analysis of spallation in relaxing media presented in Section 1.3 shows a correlation among the initial damage rate, the unloading rate in the incident shock pulse, and the freesurface velocity profile that is measured. Using this analysis, the initial damage rate can be estimated directly from the free-surface velocity profile.The typical behavior of materials of different classes-metals and alloys, brittle single crystals and glasses, and elastomers-is described in Section 1.4. A series of additional factors can influence the fracture process that

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Section: Metals and Alloysmentioning

confidence: 93%

Spallation in Solids Under Shock-Wave Loading: Analysis of Dynamic Flow, Methodology of Measurements, and Constitutive Factors

Kanel¹,

Разоренов²,

Уткин³

1996

High-Pressure Shock Compression of Solids II

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“…This method has been used to determine the spall threshold in several materials including copper (Smith, 1962) and aluminum (Blinkov and Keller, 1962). Among the advantages of this method are that it requires minimal instrumentation and the experiments are relatively easy to perform.…”

Section: Other Methods Of Determining the Spall Strengthmentioning

confidence: 99%

“…Consequently, significant overstressing of the material is possible if the load is applied at a high rate. However, several thresholds of spalling (incipient fracture, intermediate stage, and the main crack formation) can be observed in samples after testing with load pulses of various durations (Smith, 1962). The existence of several thresholds is a consequence of evolution of the fracture process in time.…”

Section: Metals and Metallic Alloysmentioning

confidence: 99%

Dynamic Failure of Materials. Volume 1 - Experiments and Analyses

Antoun¹,

Seaman²,

Curran³

1998

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“…The targets utilized a tapered (6°) plug inserted into an annular ring of the same material to minimize the effects of edge rarefactions. 12 All tests were performed with compressed-gas guns of either 63.5-mm or 102-mm bore. The guns were equipped with systems to measure projectile velocity and impact tilt, as well as diagnostic equipment for data recording.…”

Section: Experimental Techniquesmentioning

confidence: 99%

Dynamic properties of high-purity beryllium

Christman

Froula

1970

AIAA Journal

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Tests were conducted on high-purity beryllium plate to determine the Hugoniot equation of state and shock wave profile up to 50 kbar, and the spall threshold for elastic pulse widths of 0.2, 0.4, and 0.8 jusec, using flat-plate impact techniques. Tests were carried out at material temperatures of 22°C and 260°C. This beryllium was found to have a two-wave elasticplastic structure with a highly ramped transition from the elastic precursor to the plastic wave. No change in the material equation of state was observed for a temperature increase of 22°C to 260°C. The spall threshold (as defined by the onset of microcracking) was found to be time dependent, with impact velocity required for spall increasing with decreasing pulse width, and temperature dependent, with velocity increasing with increasing temperature.

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Three Low-pressure Spall Thresholds in Copper

Cited by 12 publications

References 0 publications

Spallation in Solids Under Shock-Wave Loading: Analysis of Dynamic Flow, Methodology of Measurements, and Constitutive Factors

Spallation in Solids Under Shock-Wave Loading: Analysis of Dynamic Flow, Methodology of Measurements, and Constitutive Factors

Dynamic Failure of Materials. Volume 1 - Experiments and Analyses

Dynamic properties of high-purity beryllium

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