PHYSICAL PROPERTY STUDIES OF ADDITIVE MANUFACTURED SHAPED CHARGE WARHEADS

In this thesis, an investigation into fabricating a copper shaped charge warhead using low-cost 3D printing and sintering capabilities to enable limited production shaped charge liners in theater. Initial studies investigated 3D printed copper discs to optimize the density using a copper/PLA filament within a Fused Disposition Modeling (FDM) printer. Variation in both 3D printing densities and sintering cycles (temperature and duration) enabled empirical correlations to reach densities up to 92% theoretical maximum density. Material characterization including hardness, density, strain rate compression, and shock impact studies enabled determination of the Hugoniot equation of state parameters for both the sintered Cu and un-sintered PLA/Cu samples. Through the incorporation of measured properties of the 3D printed Cu (both sintered and un-sintered), hydrocode modeling was performed and compared to subtractive manufactured bulk copper liners. A final study investigated the penetration performance of both 3D printed shape charge liners within both sintered and un-sintered configurations and comparing to traditional machined copper. Penetration performance was determined by the penetration depth and volume achieved in a series of Rolled Homogeneous Armor (RHA) witness plates.Distribution Statement A. Approved for public release: Distribution is unlimited.Lieutenant, United States NavyCAMRE Monterey Ca, 9394

Ballistic Protection of Military Shelters from Mortar Fragmentation and Blast Effects using a Multi layer Structure

In addition to its usage as a top attack ammunition in the battle field against troops, 120 mm mortar bomblethas been recently used in the terror attacks against military shelters and civil constructions. This research studiesthe protection of vehicle and personnel military shelters against mortar fragmentation warhead projectile and it’sdestroying effects. The mortar warhead threat combines both blast load and ballistic fragment penetration effects. Composite structure layers are proposed herein to be integrated with concertina walls to achieve full protection against the mortar projectile destroying effects. The current paper investigates the ability of the proposed layers to stop the mortar’s fragments and to mitigate its blast load. The velocity and the mass distribution of the produced projectile fragments were estimated using Split-X software. Besides, the ability of the proposed protection layers to stop the fragments and mitigate the blast wave was evaluated using AUTODYN hydrocode. A static firing test was then performed to validate the theoretical results and verify the effectiveness of the proposed protection added layers. The current study showed that the proposed composite layers are sufficient to protect the military shelters from the mortar’s destroying ballistic effects

Shaped charges having a porous tungsten liner-an experimental and theoretical study of metal compression, jet formation and penetration mechanics

The use of porous tungsten as a liner for shaped charges to improve their penetration was proposed by Ki-Hwan Oh in his invention disclosure Shock Extrusion of Ingots from Powders or Solids , at the New Mexico Institute of Mining and Technology, Socorro NM on June 7, 1988. The intention was to increase the ductility of the normally brittle metal by heating the liner to a high temperature by shock compaction during its acceleration just before jet formation. The feasibility of increasing the ductility of tungsten in this way is the subject of the present study. The theory and prior experimental studies of porous metal compression by shock waves are reviewed, with special attention to ways for determining the temperature of the compressed material. In this theoretical study a new equation of state is developed, and experimental shaped charges with porous tungsten liners are designed and tested. One of the shaped charges was also modeled on a computer for this study. An improved equation of state for porous tungsten is developed and compared with experimental data from the literature and other equations of state. The proposed equation of state shows improved correlation to experimental data for tungsten with high initial porosity. This is achieved while maintaining the close correlation to data obtained by most equations of state at higher initial densities. After preliminary studies, two shaped charge liner designs having porous tungsten liners with initial densities of 65% and 80% of the solid density were designed, manufactured, and test fired. Steel target plates were used to determine the penetration. As shown by the flash radiography, the jets formed were particulated on a small scale, causing the density of the jets to diminish with distance from the charge. A relatively long distance between the shaped charge and the target plates was required to provide room for the flash radiographs. This caused low jet densities and a particulated jet that had little penetration into the target plates. The jet formation for the liner with initial density 65% of the solid was modeled by continuum hydrodynamic computations using Lawrence Livermore National Laboratory\u27s CALE computer code. Near zero strength was used for the jet after formation, as well as a fitted equation of state for tungsten with low initial porosity. The modeling confirmed that low strength in the jet formation caused the fine particulation of the jet as it stretches. By using a combination of techniques developed in this work, improved temperature determinations were made. These indicated that the temperature of the shock-compressed tungsten liner varied from 350°C at the sides of the cone to 2,087°C at the apex. The shaped charge needs to be redesigned in order to achieve the temperatures of approximately 1000°C required to beneficially change the properties of tungsten. The study concludes with recommendations for future work. Proposals for shaped charges with initially porous tungsten liners that may form coherent jets are made. A test method to verify predicted penetration characteristics of finely particulated jets, developed in this study, is discussed

Feasibility study of an explosive gun

Feasibility of high performance, explosively driven device, and calculations for deformable piston light gas gu

Thermal and Mechanical Studies of Thin Spray-On Liner (TSL) for Concrete Tunnel Linings

The thesis presents a summary of Thin Spray-On Liner (TSL) effects on concrete. Three aspects, fire insulation, adhesion strength on concrete surface and load carrying capacity (i.e. flexural strength) on segmental concrete liners, are presented. Small-scale to full-scale laboratory tests were conducted using ASTM standards or devised methods. The TSL effects on three aspects were then compared with the results for uncoated concrete specimens. Numerical analyses using TEMP/W for the thermal response of TSL and a FE program, ABAQUS for the mechanical response of TSL were respectively carried out and compared with the measured results. Additionally, numerical analyses in respect to the joint rotational stiffness for the modern joint and the flexible joint were performed. The TSL effect on the flexible joint was also evaluated. Based on the results of this study, it is revealed that TSL is an excellent fire insulating material as well as a structural substrate material. The TSL coating can reduce the heat transmitted in the concrete during a fire. Also, the TSL coating can reduce concrete spalling and crack propagation during failure. The load carrying capacity increase of a segmental tunnel liner is also found

The effects of 3D printed material properties on shaped charge liner performance

© Cranfield University, 2019Shaped charges operate by explosively loading a (typically metallic) liner to produce a jet travelling at extremely high velocity (9-12 km/s). Such explosive loading involves highly non-linear transient phenomena. As such, a very wide range of physical processes must be considered to enable accurate characterisation of such events – with material behaviour within these (pressure / strain-rate) regimes providing insight into problems ranging from shaped charge performance itself through to formation of new material phases at high pressures. Unlike other high strain impact events, the shaped charge phenomenon results in hydrodynamic material flow of the liner which is an integral aspect of the shaped charge design. As such, the study of shaped charge liners has been the subject of numerous scientific research studies for over 50 years since its discovery. When explosively loaded, the liner is stretched extensively during their elongation to form a jet. The jet length depends on the ductility of the liner material, and this is strongly linked to the microscopic crystal structure, which depends on the original material properties and the processes used to produce the liners. There are several processes currently used for liner production. This thesis outlines the different liner production techniques, their advantages/disadvantages and explores the potential of employing additive manufacturing (3D printing) technique for shaped charge liner production. As 3D printed parts are being considered as a possible replacement for conventionally processed parts, this PhD work fits into this long-term vision; with built parts compared in density and mechanical strength to their bulk material equivalents. More so, 3D printing is shown to present some potential benefits for the production of efficient liners including high precision, cost-effectiveness and the potential to realise customized geometries. The use of fine powders may also allow alternative microstructures to be produced with potentially interesting results. This element of the study forms the first part of this thesis, aimed at investigating the mechanism elucidating the performance of 3D printed liners processed through direct metal laser sintering process (selective laser sintering) and filament deposition modelling processes (Polylactic Acid). The next part of this work provided additional insights on the additive manufactured processed employed through investigation of the dynamic behaviour of polylactic acid, employed in the filament deposition modelling process and static (optical and scanning micrographs) observation of the laser sintered liners in their as - manufactured and deformed state, in comparison with traditional machined liners. Autodyn 2D numerical hydrocode was employed to understand how temperature influences the deformation pattern (grain refinement); providing new insights on liner deformation. Finally, a novel computational technique to determine the Virtual Origin of shaped charges was developed to provide a ready route to predict more accurate SC performance

Criteria of design improvement of shaped charges used as oil well perforators

In addition to its various military applications, shaped charges have been used in oil industry as an oil well perforator (OWP) to connect oil and gas to their reservoirs. The collapse of the liner material under the explosive load produces a hypervelocity jet capable of achieving a deep penetration tunnel into the rock formation. The achieved penetration depends on the OWP design, which includes the geometry and the material of the explosive and the liner as well as the initiation mode and the casing of the shaped charge. The main purpose of this research is to assess the performance of OWP with different design aspects in terms of its penetration depth into concrete material.This research employed the Autodyn finite difference code to model the behaviour of OWPs in the stages of liner collapse, jet formation and jet penetration. The design parameters of OWPs were studied quantitatively to identify the effect of each individual parameter on the jet characteristics and the jet penetration depth into concrete material according to the API-RP43 standard test configuration. In order to validate the Autodyn jetting analysis, this research compared the jetting simulation results of copper OWP liners with those obtained from flash x-ray measurements while the numerical jet penetration into the laminated concrete target was validated experimentally by the static firing of OWPs. Above-mentioned experiments were designed and performed in this project.The validated hydrocode was implemented in this research to study the effects of the concrete target strength, the liner material and the liner shape on the jet penetration depth into concrete targets.For the target strength, the traditional virtual origin (VO) penetration model was modified to include a strength reduction term based on Johnson’s damage number and the effect of the underground confinement pressure using Drucker-Prager model. The VO analytical model is also implemented in the liner material study to account for the jet density reduction phenomena and its induced reduction of jet penetration capability. The jets obtained from machined copper and zirconium liners and from copper-tungsten powder liner all exhibited the density reduction phenomena. The modified VO model considers the non-uniform distribution of jet density based on the jet profile analysis using Autodyn and the experimental soft recovery for some tested liners. The results lead to a modified VO penetration model including the non-uniform jet density effect.For zirconium liner material, numerical and analytical studies were conducted for different flow velocities and different collapse angles in order to determine the boundaries between the jetting and non-jetting phases and whether a coherent or a non-coherent jet will form. This study indicated that the suggested four different liner shapes (i.e. the conical, the biconical, the hemispherical and the bell) will produce coherent jet when the zirconium is used as OWP liner.The validated Autodyn hydrocode is also used in this thesis to calculate the velocity difference between two neighbouring zirconium jet fragments. The velocity difference is related directly to the breakup time of an OWP jet, and thus, it is calculated for a range of zirconium liners with different liner wall thicknesses. The calculated values of velocity difference gave a clear insight for the breakup time formulae for zirconium jet in terms of the liner thickness and the charge diameter.EThOS - Electronic Theses Online ServiceEgyptian Armament AuthorityGBUnited Kingdo

Solid rocket motor internal insulation

Internal insulation in a solid rocket motor is defined as a layer of heat barrier material placed between the internal surface of the case propellant. The primary purpose is to prevent the case from reaching temperatures that endanger its structural integrity. Secondary functions of the insulation are listed and guidelines for avoiding critical problems in the development of internal insulation for rocket motors are presented

Engineering applications of organic surfactant modified bentonite in sorptive soil barriers.

Earthen barriers such as CCLs and GCLs have been employed in geotechnical practices to provide a low permeability hydraulic barrier since long time ago. These types of barriers exhibited satisfactory performance for many applications such as landfills. The performance of low permeability barriers is based on the swelling potential of their component, which is mostly Na-bentonite, in contact with polar fluids such as water. However, the acceptable range of conductivity cannot be achieved by traditional earthen barriers when they are permeated by non-polar fluids such as gasoline. This phenomenon occurs due to the incompatibility of earthen barrier constituent with non-polar compounds. Also, the traditional earthen barriers are not able to retard the contaminant transport due to their negligible reactivity with organic compounds. As a result, the application of low permeability barriers was limited to polar and non-contaminated flows. In this study, the performance of traditional earthen barriers as a hydraulic and chemical barrier was enhanced by introducing an organically modified amendment (HDTMA-bentonite) to traditional earthen barrier’s components

Aeronautical engineering: A special bibliography with indexes, supplement 82, April 1977

This bibliography lists 311 reports, articles, and other documents introduced into the NASA scientific and technical information system in March 1977