Was it a bomb?

Firrao, Donato; Ubertalli, Graziano; Cordano, E.

doi:10.1080/135993799349072

Cited by 7 publications

(9 citation statements)

References 17 publications

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“…Therefore, at distances above the reported limits, the elasticity theory can be applied to transform surface overpressures into surface-applied shear stresses. [1,4] …”

Section: A Specimen Deformationmentioning

confidence: 99%

“…Calculations of the maximum shear stress arising from the overpressure at the detectability threshold can be attempted by the use of elasticity theory formulations [4] and the results can be compared with the minimum shear stress necessary to form slip bands or twins. [1] However, experimental proofs of the validity of the approach do not exist.…”

Section: Introductionmentioning

confidence: 98%

“…[1,2] At some distance from an explosive charge, macro effects vanish; only microstructural variations, such as recrystallization phenomena, intense slip bands or mechanical twins, and possibly phase transformations, are present, with the former to disappear first as distance increases. In the case of small charge explosions, macro effects are restricted to very small charge-to-target distances (on the order of tens of millimeters), whereas at slightly larger distances, most of the variations are of the crystal alteration type.…”

Section: Introductionmentioning

confidence: 99%

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Microstructural Effects in Face-Centered-Cubic Alloys after Small Charge Explosions

Firrao

Matteis

Scavino

et al. 2007

Metall Mater Trans A

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Effects on metal targets after an explosion include the following: fracture, plastic deformation, surface modifications, and microstructural crystallographic alterations with ensuing mechanical properties changes. In the case of small charge explosions, macroscopic effects are restricted to small charge-to-target distances, whereas crystal alterations can still be observed at moderate distances. Microstructural variations, induced on gold-alloy disk samples, as compared to previous results on AISI 304Cu steel samples, are illustrated. The samples were subjected to blast-wave overpressures in the range of 0.5 to 195 MPa. Minimum distances and peak pressures, which could still yield observable alterations, were especially investigated. Blast-related microstructural features were observed on the explosion-exposed surface and on perpendicular cross sections. Analyses using X-ray diffraction (XRD) were performed to identify modifications of phase, texture, dislocation density, and frequency of mechanical twins, before and after the explosions. Optical metallography (OM) and scanning electron microscopy (SEM) observations evidenced partial surface melting, zones with recrystallization phenomena, and crystal plastic deformation marks. The latter marks are attributed to mechanical twinning in the stainless steel and to cross-slip (prevalent) and mechanical twinning (possibly) in the gold alloy.

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“…Therefore, at distances above the reported limits, the elasticity theory can be applied to transform surface overpressures into surface-applied shear stresses. [1,4] …”

Section: A Specimen Deformationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Microstructural Effects in Face-Centered-Cubic Alloys after Small Charge Explosions

Firrao

Matteis

Scavino

et al. 2007

Metall Mater Trans A

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“…On this bases, and neglecting the influence of alloying elements in the case of the aluminum alloy, the relationship by Firrao et al [1] yields a τ c,tw value of 33 MPa for α-brass, 69…”

Section: Discussionmentioning

confidence: 99%

“…Effects on metal targets after an explosion include fracture, macroscopic and localized plastic deformations, surface modifications and microstructural crystallographic alterations [1]. For small charge explosions, macroscopic effects are restricted to very small charge-to-target distances (of the order of tens of millimeters), whereas, at larger distances, most alterations are crystallographic.…”

Section: Introductionmentioning

confidence: 99%

Recent Developments on the Microstructural Effects Caused by Small-Charge Explosions in FCC Alloys

Firrao

Matteis

Pozzi

2010

MSF

Self Cite

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Abstract. Metals exposed to small charge explosions, even in absence of overall deformation, show characteristic and permanent microstructural features, that can be related to blast wave properties, e.g. to the charge mass and the charge-to-target distance. In particular, Face Centered Cubic (FCC) alloys with low stacking fault energy may exhibit mechanical twinning due to the high strain rate caused by an explosion, even if in slower processes they mainly deform by slip. In some forensic science investigations, these crystallographic modifications, and particularly the occurrence of twinning, may be among the few remaining clues of a small charge explosion, and may be useful to hypothesize the nature and location of the charge. A wide experimental campaign was performed to correlate the blast wave properties with the ensuing modifications of FCC metal targets, and to investigate the microscopic deformation mechanisms leading to these modifications. In particular, it was attempted to identify the threshold conditions (charge-to-target distance, charge mass, and hence applied stress) that yield barely detectable microstructural modifications, and to study the transition from slip to twinning. FCC metal alloys, with low (α-brass, stainless steel), intermediate (copper, gold alloy), or high (aluminum alloy) stacking fault energy, were exposed to blast waves (caused by 50 or 100 g plastic explosive charges located at increasing charge-to-target distances) and then analyzed by X-ray diffraction, optical microscopy, scanning electron microscopy, and electron backscattered diffraction imaging. A comprehensive review of the most significant findings of the whole research, together with theoretical considerations on the slip and twinning deformation mechanisms, is here presented.

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