An Analytical Study of Projectile Penetration into Rock (original) (raw)
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Advances in Projectile Penetration Mechanism in Soil Media
Applied Sciences
The penetration to geological shield occurs in many situations at various velocities and scales, for example, meteor-cratering, pile driving, falling of objects from high-rise building construction, and debris/fragments from failed components. The soil media is an efficient energy dissipation system and effective shock protection shield. Impact circumstances are currently getting widespread attention. A lot of research has been done on soil media for impact and penetration. The phenomenon of dynamic penetration in heterogeneous particulate soil medium is very complex and the target soil media under dynamic impact especially under high speed and deep penetration neither behave completely as solid nor as liquid. The topics of recent research interest in the field of penetration to soil media and their significant findings are critically reviewed in the present study. The dedicated review of analytical, empirical, experimental, and computational methods to predict the response of soils...
Experimental and functional analysis of rock crystal projectiles
[Conference: IV International Experimental Archaeology Conference, At Burgos] Functional studies in rock crystal industries from Cova Eirós (Lugo, Galicia) have given interesting results, suggesting a frequent use of this raw material (configured or not) in the elaboration of projectile elements. Rock crystal is a material that have barely been taken into account in archaeological literature, and even less in functional issues. That is why we present an experimental programme of macro and micro trace analysis in rock crystal pieces used as projectile points. Due to the microcrystalline character of this mineral, and its theoretical fragility, we consider appropriate to make an experimental comparison, in macro and micro levels, between fractures produced by the impact of the projectile (bending fractures) and those produced by flexion or by trampling. Furthermore, we present different methods for the analysis and graphic documentation of this objects that, because of rock crystal's characteristic translucency, can be considered unsuitable for a study of these characteristics.
A Mechanics Approach to Projectile Penetration
1970
: In the program reported in the paper, a mathematical model was developed which describes the mechanism of the normal penetration of metallic targets. The model considers all the forces acting on the projectile during penetration, bearing in mind that it is deformed during the penetration and that its effective mass increases during penetration due to the concomitant motion of part of the target mass. With the aid of the mathematical expressions the projectile's velocity after perforation can be calculated by substituting the information on the cavity diameter obtained experimentally. Another part of this program consisted of a series of penetration experiments. The experimental results for the velocity drop due to normal perforation of metallic plates were compared with the mathematical model. (Author)
Engineering models of high speed penetration into geological shields
Central European Journal of Engineering, 2014
The survey is dedicated to approximate empirical and analytical models which were suggested for describing high-speed penetration into geological shields. This review differs from the previously published reviews on this topic in the following respects: (i) includes a large number of models; (ii) describes models suggested during recent years; (iii) much attention is given to models which have been originally published in Russian and are not well known in the West. References list includes 81 items.
Rainbow in the dark. The identification of diagnostic projectile impact features on rock crystal
Journal of Archaeological Science: Reports
Over the last years, functional analyses and projectile fracture analyses on non-chert tools are becoming widespread and are drawing more attention in the archaeological literature. The actual tendencies of conducting holistic studies of the archaeological sites and their materials is allowing to obtain a better quality of data and a better understanding of the subsistence patterns of hunter-gatherer societies. In this way, rock crystal and other types of minerals and rocks of the quartzose group are getting a significant presence in the literature. In this paper, we intend to address a comprehensive approach, both macroscopic and microscopic, to an assemblage of experimental rock crystal projectiles to shed light on the identification of the diagnostic features of the use of small rock crystal pieces as projectile points. Aiming to avoid misidentifications, we did not only follow a sequential experiment design, but also carried out a comparative analysis between impact fractures and knapping fractures, marks from bipolar knapping on an anvil, and intentional bending fractures. Besides, in the elaboration of the experimental projectile assemblage we used different sets of targets to document possible differences in the quantity and disposition of the wear impact traces. This small number of recently published articles focusing exclusively on rock crystal have facilitated a better understanding of the functionality of this raw material, complementing and refining previous knowledge of its behavior on a microscopic scale (Pignat and Plisson, 2000; Plisson, 2008; Lombard, 2011). Nonetheless, important questions remain about the appearance of certain types of marks, as well as the identification of certain groups of deformations that could be generated by equifinal processes, such as knapping, retouching, taphonomic alterations, or use. The origins of different fracture types are also not well-understood, not only due to rock crystal's particular energy distribution (Rodríguez-Rellán, 2016a, b), but also due to certain obstacles to analysis, such as its transparency. The lack of specific research on projectile fractures in rock crystal is being addressed with the publication of new experimental studies (Fernández-Marchena et al.,
Projectile penetration in granular material
SHOCK COMPRESSION OF CONDENSED MATTER - 2019: Proceedings of the Conference of the American Physical Society Topical Group on Shock Compression of Condensed Matter, 2020
Penetration depth is the most important parameter in terminal ballistics. Here only the case of projectiles penetrating granular medium is considered. Laboratory and field tests have shown that projectile characteristics such as mass, size, and nose shape, and target characteristics such as strength and density determine the depth of penetration. Analyses of full flight data recorded by onboard data acquisition system (G-Rec) are presented. These tests have revealed very high decelerations at impact with extensive particle fracture along the path of the projectile. Particle size distribution analysis of the sample collected from the projectile tip shows two to three orders of magnitude reduction in size. For similar impact velocities and target densities, Poncelet's coefficient does not vary with tip shape.
Experimental and functional analyses of rock crystal projectiles
Playing with the time. Experimental archaeology and the study of the past, 2017
Functional analyses on rock crystal tools are scarce. Due to the microlithic character of some elements recovered in NW Iberian sites, we believe that some of them could have been used as projectiles. To test this hypothesis we carried out a pilot experiment that aims to evaluate if it is possible to identify projectiles in rock crystal. We followed a dual approach to study the deformations derived from impact. Studying the pieces before and after use, we analyzed macroscopic fractures and microscopic features. Thus we could verify what types of marks were created after shooting and which methodology should be followed in a large-scale experiment. Resumen: Los análisis funcionales sobre útiles de cristal de roca son muy escasos. Debido al carácter microlítico de algunos elementos localizados en yacimientos del NW Ibérico, creemos que algunos podrían haber sido usados como proyectiles. Para comprobar esta hipótesis programamos una experimentación piloto con el objetivo de comprobar si se pueden identificar elementos de proyectil en cristal de roca. Se realizó una doble aproximación a las deformaciones por impacto comparando el antes y el después del uso: documentación de fracturas macroscópicas y análisis microscópico. De esta manera se pudo comprobar qué tipos de estigmas se crearon sobre las piezas y cuál es el método de análisis que se debe priorizar en un próximo experimento a gran escala.
Meteoritics & Planetary Science, 2007
Scaling laws describing crater dimensions are defined in terms of projectile velocity and mass, densities of the materials involved, strength of the target, and the local gravity. Here, the additional importance of target porosity and saturation, and an overlying water layer, are considered through 15 laboratory impacts of 1 mm diameter stainless steel projectiles at 5 km s −1 into a) an initially uncharacterized sandstone (porosity ~17%) and b) Coconino Sandstone (porosity ~23%). The higher-porosity dry sandstone allows a crater to form with a larger diameter but smaller depth than in the lower-porosity dry sandstone. Furthermore, for both porosities, a greater volume of material is excavated from a wet target than a dry target (by 27-30%). Comparison of our results with Pi-scaling (dimensionless ratios of key parameters characterizing cratering data over a range of scales) suggests that porosity is important for scaling laws given that the new data lie significantly beneath the current fit for ice and rock targets on a π v versus π 3 plot (π v gives cratering efficiency and π 3 the influence of target strength). An overlying water layer results in a reduction of crater dimensions, with larger craters produced in the saturated targets compared to unsaturated targets. A water depth of approximately 12 times the projectile diameter is required before craters are no longer observed in the targets. Previous experimental studies have shown that this ratio varies between 10 and 20 . In our experiments ~25% of the original projectile mass survives the impact.