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Constitutive model for porous materials

Description: A simple pressure versus porosity compaction model is developed to calculate the response of granular porous bed materials to shock impact. The model provides a scheme for calculating compaction behavior when relatively limited material data are available. While the model was developed to study porous explosives and propellants, it has been applied to a much wider range of materials. The early development of porous material models, such as that of Hermann, required empirical dynamic compaction data. Erkman and Edwards successfully applied the early theory to unreacted porous high explosives using a Gruneisen equation of state without yield behavior and without trapped gas in the pores. Butcher included viscoelastic rate dependance in pore collapse. The theoretical treatment of Carroll and Holt is centered on the collapse of a circular pore and includes radial inertia terms and a complex set of stress, strain and strain rate constitutive parameters. Unfortunately data required for these parameters are generally not available. The model described here is also centered on the collapse of a circular pore, but utilizes a simpler elastic-plastic static equilibrium pore collapse mechanism without strain rate dependence, or radial inertia terms. It does include trapped gas inside the pore, a solid material flow stress that creates both a yield point and a variation in solid material pressure with radius. The solid is described by a Mie-Gruneisen type EOS. Comparisons show that this model will accurately estimate major mechanical features which have been observed in compaction experiments.
Date: January 1, 1982
Creator: Weston, A.M. & Lee, E.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department

Analysis of NSWC quasi-static compaction data for porous beds of ball powder, melamine, and Teflon, using structural compaction model

Description: A structural compaction model is used to correlate NSWC quasi-static compaction data on porous beds of six (6) different materials, i.e., four (4) ball powders, melamine, and Teflon. Initial densities of the porous beds ranged from 44 percent solid theoretical maximum density (TMD) to 70 percent TMD. Maximum compacted densities were about 90 percent TMD except for Teflon which was compacted to approximately 98 percent TMD. Pressures calculated by the model, plotted as a function of percent TMD, agree well with the NSWC data.
Date: April 6, 1983
Creator: Weston, A.M. & Lee, E.L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

KOVEC studies of radioisotope thermoelectric generator response (In connection with possible NASA space shuttle accident explosion scenarios)

Description: The Department of Energy (DOE) commissioned a study leading to a final report (NUS-4543, Report of the Shuttle Transportation System (STS) Explosion Working Group (EWG), June 8, 1984), concerned with PuO/sub 2/ dispersal should the NASA space shuttle explode during the proposed Galileo and ISPN launches planned for 1986. At DOE's request, LLNL furnished appendices that describe hydrocode KOVEC calculations of potential damage to the Radioisotope Thermoelectric Generators, fueled by PuO/sub 2/, should certain explosion scenarios occur. These appendices are contained in this report.
Date: June 26, 1984
Creator: Walton, J.; Weston, A. & Lee, E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

TRILIN: a computer analysis of the transient response of elastic structures

Description: The computer code TRILIN employs a force method that uses prismatic beam- type elements and discrete masses for the analysis of the transient response of linearly elastic, three-dimensional, frame-type structures subjected to arbitrary loading conditions. Each beam element is capable of resisting tension, bending, and torsion. A global stiffness matrix is obtained by inverting the flexibility relationships. Modal superposition is used to solve the governing equations. (auth)
Date: October 26, 1973
Creator: Miller, A.B.; Weston, A.M.; Hallquist, J.O. & Bernreuter, D.L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department

Modeling shock initiation in Composition B

Description: A hydrodynamic modeling study of the shock initiation behavior of Composition B explosive was performed using the {open_quotes}Ignition and Growth of Reaction in High Explosive{close_quotes} model developed at the Lawrence Livermore National Laboratory. The HE (heterogeneous explosives) responses were computed using the CALE and DYNA2D hydrocodes and then compared to experimental results. The data from several standard shock initiation and HE performance experiments was used to determine the parameters required for the model. Simulations of the wedge tests (pop plots) and failure diameter tests were found to be sufficient for defining the ignition and growth parameters used in the two term version of the computational model. These coefficients were then applied in the response analysis of several Composition B impact initiation experiments. A description of the methodology used to determine the coefficients and the resulting range of useful application of the ignition and growth of reaction model is described.
Date: May 1, 1993
Creator: Murphy, M. J.; Lee, E. L.; Weston, A. M. & Williams, A. E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department

RHIC 10 Hz global orbit feedback system

Description: Vibrations of the cryogenic triplet magnets at the Relativistic Heavy Ion Collider (RHIC) are suspected to be causing the horizontal beam perturbations observed at frequencies around 10 Hz. Several solutions to counteract the effect have been considered in the past, including a local beam feedback system at each of the two experimental areas, reinforcing the magnet base support assembly, and a mechanical servo feedback system. However, the local feedback system was insufficient because perturbation amplitudes outside the experimental areas were still problematic, and the mechanical solutions are very expensive. A global 10 Hz orbit feedback system consisting of 36 beam position monitors (BPMs) and 12 small dedicated dipole corrector magnets in each of the two 3.8 km circumference counter-rotating rings has been developed and commissioned in February 2011. A description of the system architecture and results with beam will be discussed.
Date: March 28, 2011
Creator: Michnoff, R.; Arnold, L.; Carboni, L.; Cerniglia, P; Curcio, A.; DeSanto, L. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department