Application of 3D image correlation for full-field transient plate deformation measurements during blast loading

Computer Vision-Based, Noncontacting Deformation Measurements in Mechanics: A Generational Transformation

Requirements for graduate theses and dissertations are determined by the graduate school and the departmental committee headed by a major advisor under whom a student works. Contents require a report on research usually accompanied by a review of the literature on the subject. In form, traditional theses are written as one entity; other theses may include manuscripts for publication. The student is usually required to defend the contents and quality of the thesis in an oral session before his or her committee. To establish a time line and to work on writing the thesis throughout the graduate program will relieve some pressure at the end of the program. The student may be expected to publish at least a part of the thesis, usually as a journal article.

Graduate Theses and Dissertations

The structural response of a stainless steel plate subjected to the combined blast and sand impact loading from a buried charge has been investigated using a fully coupled approach in which a discrete particle method is used to determine the load due to the high explosive detonation products, the air shock and the sand, and a finite element method predicts the plate deflection. The discrete particle method is based on rigid, spherical particles that transfer forces between each other during collisions. This method, which is based on a Lagrangian formulation, has several advantages over coupled Lagrangian–Eulerian approaches as both advection errors and severe contact problems are avoided. The method has been validated against experimental tests where spherical 150 g C-4 charges were detonated at various stand-off distances from square, edge-clamped 3.4 mm thick AL-6XN stainless steel plates. The experiments were carried out for a bare charge, a charge enclosed in dry sand and a charge enclosed in fully saturated wet sand. The particle-based method is able to describe the physical interactions between the explosive reaction products and soil particles leading to a realistic prediction of the sand ejecta speed and momentum. Good quantitative agreement between the experimental and predicted deformation response of the plates is also obtained.

A discrete particle approach to simulate the combined effect of blast and sand impact loading of steel plates

https://apps.dtic.mil/dtic/tr/fulltext/u2/a595399.pdf

Parameterization of the porous-material model for sand with different levels of water saturation

A new materials model for sand has been developed in order to include the effects of the degree of saturation and the deformation rate on the constitutive response of this material. The model is an extension of the original compaction materials model for sand in which these effects were neglected. The new materials model for sand is next used, within a non-linear-dynamics transient computational analysis, to study various phenomena associated with the explosion of shallow-buried and ground-laid mines. The computational results are compared with the corresponding experimental results obtained through the use of an instrumented horizontal mine-impulse pendulum, pressure transducers buried in sand and a post-detonation metrological study of the sand craters. The results obtained suggest that the modified compaction model for sand captures the essential features of the dynamic behavior of sand and accounts reasonably well for a variety of the experimental findings related to the detonation of shallow-buried or ground-laid mines.

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The Effect of Degree of Saturation of Sand on Detonation Phenomena Associated with Shallow-Buried and Ground-Laid Mines

A transient non-linear dynamics analysis of the detonation of a landmine buried to different depths in water-saturated sand is carried out in order to determine the resulting impulse loading The results obtained are compared with their experimental counterparts obtained using the vertical impulse measurement fixture (VIMF), a structural mechanical device that enables direct experimental determination of the blast-loading impulse The mechanical response of the structural steel used in the construction of the VIMF and the hydrodynamic response of the TNT high-energy high-pressure detonation products generated during detonation of a mine and of the air surrounding the VIMF are represented using the standard materials models available in the literature The mechanical response of the sand surrounding the mine, on the other hand, is represented using the present authors' recent modified compaction model [1], which incorporates the effects of degree of saturation and the rate of deformation, two important eff

Impulse loading resulting from shallow buried explosives in water-saturated sand:

A nonlinear‐dynamics transient computational analysis of the explosion phenomena associated with detonation of 100g of C4 high‐energy explosive buried at different depths in sand is carried out using the AUTODYN computer program. The results obtained are compared with the corresponding experimental results obtained in Ref. [1]. To validate the computational procedure and the materials constitutive models used in the present work, a number of detonation‐related phenomena such as the temporal evolutions of the shape and size of the over‐burden sand bubbles and of the detonation‐products gas clouds, the temporal evolutions of the side‐on pressures in the sand and in air, etc. are determined and compared with their experimental counterparts. The results obtained suggest that the agreement between the computational and the experimental results is reasonable at short postdetonation times. At longer post‐detonation times, on the other hand, the agreement is less satisfactory primarily with respect to the size and shape of the sand crater, i.e. with respect to the volume of the sand ejected during explosion. It is argued that the observed discrepancy is, at least partly, the result of an inadequacy of the generic materials constitutive model for the sand which does not explicitly include the important effects of the sand particle size and the particle size distribution, as well as the effects of moisture‐level controlled inter‐particle friction and cohesion. It is further shown that by a relatively small adjustment of the present materials model for sand to include the potential effect of moisture on inter‐particle friction can yield a significantly improved agreement between the computed and the experimentally determined sand crater shapes and sizes.

/pdf/a-computational-analysis-of-detonation-of-buried-mines-ksyzkmwp53.pdf

A Computational Analysis of Detonation of Buried Mines

A series of transient non-linear dynamics computational analyses of the explosion phenomena accompanying the detonation of a 100 g C4 mine buried in sand to different depths is carried out using the software package AUTODYN. The mechanical response of sand under high deformation-rate conditions has been represented using the modified compaction material model developed in our recent work (1). While the mechanical response of the other attendant materials (air, gaseous-detonation products and AISI 1006 mild steel) is accounted for using the material models available in literature. The results obtained (specifically, the temporal evolution of the sand overburden shape and pressure at various locations in air above the detonation site) were compared with their experimental counterparts for a (50wt%-sand/50wt.%-clay) soil obtained recently by Foedinger (2). The comparison revealed that the modified compaction material model for sand can account reasonably well for the magnitude, spatial distribution and the temporal evolution of the dynamic loads accompanying detonation of shallow-buried mines in soils with various clay and water contents.

/pdf/application-of-the-modified-compaction-material-model-to-the-1fr4i1zicu.pdf

Application of the modified compaction material model to the analysis of landmine detonation in soil with various degrees of water saturation

Shallow buried explosives pose a significant threat to lightweight vehicles and their onboard personnel. To date, designers of lightweight vehicles are limited in their knowledge of what occurs during the blast. The high intensity, short term loading imparted by the explosion is enormously complex and can be significantly affected by a number of parameters including the size, shape, type, detonation point and depth of burial (DOB) of the explosive and the type, density and water content of the soil. Recent advancements in numerical simulations have enabled the complex blast event to be accurately modelled by coupling Eulerian and Lagrangian analyses: the former is well suited to modelling the blast and while the latter, the structural response. Further validation of the modelling technique is considered in the current paper, which details simulations performed utilising the coupled Eulerian-Lagrangian analysis to study the blast output of explosives buried in saturated sand. These experiments varied explo...

B. A. Cheeseman

Papers

The Effect of Degree of Saturation of Sand on Detonation Phenomena Associated with Shallow-Buried and Ground-Laid Mines

Impulse loading resulting from shallow buried explosives in water-saturated sand:

A Computational Analysis of Detonation of Buried Mines

Application of the modified compaction material model to the analysis of landmine detonation in soil with various degrees of water saturation

Blast simulation of explosives buried in saturated sand