Bulletin of the American Physical Society
20th Biennial Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 62, Number 9
Sunday–Friday, July 9–14, 2017; St. Louis, Missouri
Session U4: Ballistics II |
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Chair: William Proud, Imperial College London Room: Regency Ballroom A |
Thursday, July 13, 2017 2:15PM - 2:30PM |
U4.00001: Stretching Hollow Jets in Potential Flow John Curtis, Frank Smith, Alexander White Why model hollow elongating jets? As well as offering some interesting new mathematics, the dynamics of such jets are of potential interest in the consideration of methods of creating circular penetration cuts into targets, in understanding better the coherency of solid shaped charge jets, and possibly as a means of engendering cracking in targets over a wider target area than can be accomplished with a solid shaped charge jet. This paper presents and solves numerically the boundary-value problem of a stretching hollow jet in potential flow. The behaviour of the hollow cylindrical jet is analysed as a function of the initial inner and outer radii, the rate of stretching, and the initial radial velocity component associated with the inner radius. It is shown that under different initial conditions the hollow can close up or expand. The evolution of the associated pressure field is determined. [Preview Abstract] |
Thursday, July 13, 2017 2:30PM - 2:45PM |
U4.00002: Computational Investigation of In-Flight Temperature in Shaped Charge Jets and Explosively Formed Penetrators Peter Sable, Nathaniel Helminiak, Eric Harstad, Arne Gullerud, Jeromy Hollenshead, Eugene Hertel With the increasing use of hydrocodes in modeling and system design, experimental benchmarking of software has never been more important. While this has been a large area of focus since the inception of computational design, comparisons with temperature data are sparse due to experimental limitations. A novel temperature measurement technique, magnetic diffusion analysis, has enabled the acquisition of in-flight temperature measurements of hyper velocity projectiles. Using this, an AC-14 bare shaped charge and an LX-14 EFP, both with copper linings, were simulated using CTH to benchmark temperature against experimental results. Particular attention was given to the slug temperature profiles after separation, and the effect of varying equation-of-state and strength models. Simulations are in agreement with experimental, attaining better than 2{\%} error between observed shaped charge temperatures. This varied notably depending on the strength model used. Similar observations were made simulating the EFP case, with a minimum 4{\%} deviation. Jet structures compare well with radiographic images and are consistent with ALEGRA simulations previously conducted. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Thursday, July 13, 2017 2:45PM - 3:00PM |
U4.00003: Gun Testing Ballistics Issues for Insensitive Munitions Fragment Impact Testing Ernest Baker, Emmanuel Schultz The STANAG 4496 Ed. 1 Fragment Impact, Munitions Test Procedure is normally conducted by gun launching a projectile for attack against a munition. The purpose of this test is to assess the reaction of a munition impacted by a fragment. The test specifies a standardized projectile (fragment) with a standard test velocity of 2530\textpm 90 m/s, or an alternate test velocity of 1830\textpm 60 m/s. The standard test velocity can be challenging to achieve and has several loosely defined and undefined characteristics that can affect the test item response. This publication documents the results of an international review of the STANAG 4496 related to the fragment impact test. To perform the review, MSIAC created a questionnaire in conjunction with the custodian of this STANAG and sent it to test centers. Fragment velocity variation, projectile tilt upon impact and aim point variation were identified as observed gun testing issues. Achieving 2530 m/s consistently and cost effectively can be challenging. The aim point of impact of the fragment is chosen with the objective of obtaining the most violent reaction. No tolerance for aim point is specified, although aim point variation can be a source for IM response variation. Fragment tilt on impact is also unspecified. The standard fragment fabricated from a variety of different steels which have a significant margin for mechanical properties. These, as well as other gun testing issues, have significant implications to resulting IM response. [Preview Abstract] |
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