Bulletin of the American Physical Society
17th Biennial International Conference of the APS Topical Group on Shock Compression of Condensed Matter
Volume 56, Number 6
Sunday–Friday, June 26–July 1 2011; Chicago, Illinois
Session Z5: Composites and Polymers III: Composites |
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Chair: George Sunny, Air Force Research Laboratory Room: Renaissance Ballroom D |
Friday, July 1, 2011 11:00AM - 11:15AM |
Z5.00001: Dynamic behavior of reactive aluminum nanoparticle-fluorinated acrylic (AlFA) polymer composites Christopher A. Crouse, Brad White, Jonathan E. Spowart The dynamic behavior of aluminum nanoparticle-fluorinated acrylic (AlFA) composite materials has been explored under high strain rates. Cylindrical pellets of the AlFA composite materials were mounted onto copper sabots and impacted against a rigid anvil at velocities between 100 and 400 m/s utilizing a Taylor gas gun apparatus to achieve strain rates on the order of 10$^4$ /s. A framing camera was used to record the compaction and reaction events that occurred upon contact of the pellet with the anvil. Under both open air and vacuum environments the AlFA composites demonstrated high reactivity suggesting that the particles are primarily reacting with the fluorinated matrix. We hypothesize, based upon the compaction history of these materials, that reaction is initiated when the oxide shells on the aluminum nanoparticles are broken due an interparticle contact deformation process. We have investigated this hypothesis through altering the particle loading in the AlFA composites as well as impact velocities. This data and the corresponding trends will be presented in detail. [Preview Abstract] |
Friday, July 1, 2011 11:15AM - 11:30AM |
Z5.00002: Meso-scale simulations of particle reinforced epoxy-based composites Bradley W. White, H. Keo Springer, Jennifer L. Jordan, Jonathan E. Spowart, Naresh N. Thadhani Polymer matrix composites reinforced with metal powders often exhibit complex microstructure characteristics that can vary greatly due to differences in particle size and distribution, morphology, loading fractions, and composite processing methods. The effects of these differences in underlying microstructure on the mechanical and wave propagation behavior of these composites under dynamic loading conditions are not well understood. To better understand these effects, epoxy (Epon826/DEA) reinforced with different particle loading fractions of aluminum (20 or 40{\%} vol.), nominal particle size of aluminum (5 or 50 microns), and the addition of a stiffer second particle type (Ni, 10{\%} vol., 50 micron nominal diameter) were prepared. Microstructures of the as cast composites were obtained and used in two dimensional meso-scale simulations. The effect of varying velocity loading conditions ($>$ 400 m/s) on the wave velocity was then examined to determine the Us --Up response as a function of composite configuration. In this presentation results from the meso-scale simulations will be shown and correlated to microstructure characteristics. [Preview Abstract] |
Friday, July 1, 2011 11:30AM - 11:45AM |
Z5.00003: Composite Layering Technique for use in a Eulerian Shock Physics Code Shane Schumacher The high strength and low density of fiber reinforced composites have made them applicable to high strain rate shock environments. The modeling and simulation of such materials is difficult due to their anisotropic behavior and complex internal geometries. Fiber reinforced composites consist of a collection of layers that create a laminate. Each layer is typically transverse isotropic or orthotropic consisting of a fiber and matrix material. The creation of a layering capability in a Eulerian shock physics code can mitigate the burden of smearing and increase the accuracy of modeling fiber reinforced composites. This process is done using a sub-grid technique in an individual grid cell. The grid cell is partitioned based on layer location in the laminate and the material deformation. The volume occupied by a layer is computed and the layer computes a material response based on the cell strain field. The resulting state variables are volume weighted with the remaining layers in the given grid cell yielding a cell response. The result is a technique that requires less computation time than modeling each layer and increases the accuracy over smeared approximations. [Preview Abstract] |
Friday, July 1, 2011 11:45AM - 12:00PM |
Z5.00004: The shock response of TWCP David Wood, Paul Hazell, Gareth Appleby-Thomas, Nick Barnes The combination of high strength and low density, combined with good thermal resistance, has led to carbon-fibre composites (CFCs) becoming increasingly important in the design and construction of vehicles in the aerospace industry. However, the extreme working environment of such CFC based vehicle components makes subjection to significant transient loading events likely during their lifetime. Consequently, knowledge of the high-rate response of CFCs is crucial if the safety and performance of such aerospace systems is to be ensured. In this study the shock response of a tape wrapped CFC with a phenolic resin matrix was investigated via the plate-impact technique. The shock response of this material, with the carbon-fibre weave aligned both parallel, and perpendicular to, the impact axis was interrogated. Hugoniot relationships in the U$_{S}$-u$_{P}$ and P-v/v$_{0}$ planes were obtained and compared with similar relationships for both matrix materials and other similar CFC systems from the literature. [Preview Abstract] |
Friday, July 1, 2011 12:00PM - 12:15PM |
Z5.00005: Functional Graded Shells Subjected to Underwater Shock Shi Wei Gong This paper deals with the problem of functionally graded (FG) cylindrical shells subjected to underwater shock. A computational approach to predict the dynamic response of the FG cylindrical shells to underwater shock is presented. The effective material properties of functionally graded materials (FGMs) for the cylindrical shells are assumed to vary continuously through the shell thickness and are graded in the shell thickness direction according to a volume fraction power law distribution. Based on Doubly Asymptotic Approximation (DAA) method, the fluid-structure interaction equation for a submerged structure is derived, in which the constitutive relation for functional graded material is implemented. The coupled fluid-structure equations, relating structure response to fluid impulsive loading, are solved using coupled finite-element and boundary-element codes. The computational procedure for the prediction of transient response of the FG graded cylindrical shells subjected to underwater shock is described, with a discussion of the results. [Preview Abstract] |
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