Bulletin of the American Physical Society
16th APS Topical Conference on Shock Compression of Condensed Matter
Volume 54, Number 8
Sunday–Friday, June 28–July 3 2009; Nashville, Tennessee
Session W2: CP-2: Composites |
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Chair: Clive Siviour, University of Oxford Room: Hermitage AB |
Thursday, July 2, 2009 3:30PM - 4:00PM |
W2.00001: Dynamic Fracture of Nanocomposites and Response of Fiber Composite Panels to Shock Loading Invited Speaker: This lecture will present studies on the response of novel engineering materials to extreme dynamic loadings. In particular, the talk will focus on the behavior of sandwich composite materials to shock loading and dynamic fracture of nano-composite materials. Results from an experimental study on the response of sandwich materials to controlled blast loading will be presented. In this study, a shock tube facility was utilized to apply blast loading to simply supported plates of E-glass vinyl ester/PVC foam sandwich composite materials. Pressure sensors were mounted at the end of the muzzle section of the shock tube to measure the incident pressure and the reflected pressure profiles during the experiment. A high speed digital camera was utilized to capture the real time side deformation of the materials, as well as the development and progression of damage. Macroscopic and microscopic examination was then implemented to study the post-mortem damage. Conclusions on the relative performance of sandwich composites under blast loadings will also be discussed. Results from an experimental investigation conducted to evaluate the mechanical properties of novel materials fabricated using nano sized particles in polymer matrix will also be presented. Unsaturated polyester resin specimens embedded with small loadings of nano sized particles of TiO2 and Al2O3 were fabricated using a direct ultrasonification method to study the effects of nanosized particles on nanocomposite fracture properties. The ultrasonification method employed produced nanocomposites with excellent particle dispersion as verified by TEM. Experiments were conducted to investigate the dynamic crack initiation and rapid crack propagation in theses particle reinforced materials. High-speed digital imaging was employed along with dynamic photoelasticity to obtain real time, full-field quantification of the stress field associated with the dynamic fracture process. Birefringent coatings were used to conduct the photoelastic studies due to the opaqueness of these materials. Dynamic fracture experiments were conducted with various specimen geometries to study the complete history of dynamic crack propagation from initiation to crack branching. Results from several of these experiments were compiled to establish a relationship between the dynamic stress intensity factor, KI, and the crack tip velocity, and the behavior of the nanocomposites is compared with that of the virgin polyester matrix. The specimens used in this study and the nano- particle distribution are also shown in the figure. Crack arrest toughness increased by 64\% in the nanocomposite relative to the virgin polyester. Also, Crack propagation velocities in nanocomposites were found to be 50\% greater than those in the virgin polyester. [Preview Abstract] |
Thursday, July 2, 2009 4:00PM - 4:15PM |
W2.00002: Shock Equation of State of Single Constituent and Multi-Constituent Epoxy-Based Particulate Composites Jennifer Jordan, Dana Dattelbaum, Louis Ferranti, Gerrit Sutherland, D. Wayne Richards, Steve Sheffield, Richard Dick, Naresh Thadhani There are several studies in the literature regarding the equation of state of alumina-epoxy composites. Although these single component systems interact in a complex manor with shock waves, the addition of a second metal or ceramic particulate can result in even more complex interactions. This paper presents a review of shock loading studies on epoxy-based particulate composites, such as Al$_{2}$O$_{3}$-epoxy, Al-Fe$_{2}$O$_{3}$-epoxy, and, Al-MnO$_{2}$-epoxy. Comparisons between measured ultrasonic sound speeds and shock bulk sound speed are discussed. Finally, the relationship between equation of state parameters and particulate concentration is investigated. [Preview Abstract] |
Thursday, July 2, 2009 4:15PM - 4:30PM |
W2.00003: Shock Compression Response of Composites of THV and Ceramic Powders Christopher Neel, Naresh Thadhani The shock compression response of polymer-ceramic composites is determined using parallel plate impact tests. PVDF stress gauges are used to determine the Hugoniot in the range of 2-8 GPa. The composites consist of ceramic powders of various sizes in a THV polymer matrix. The ceramic powders used are 1, 10, and 100 micron alumina and 10 micron ZrC. The composites are heterogeneous and porous to various degrees. Measured Hugoniot results are compared with those obtained from models. The comparisons reveal that the porosity has the dominant effect and it overshadows effects due to the size or density of the particles. [Preview Abstract] |
Thursday, July 2, 2009 4:30PM - 4:45PM |
W2.00004: Polystyrene Foam EOS as a Function of Porosity and Fill Gas Roberta Mulford, Damian Swift An accurate EOS for polystyrene foam is necessary for analysis of numerous experiments in shock compression, inertial confinement fusion, and astrophysics. Plastic to gas ratios vary between various samples of foam, according to the density and cell-size of the foam. A matrix of compositions has been investigated, allowing prediction of foam response as a function of the plastic-to-air ratio. The EOS code CHEETAH allows participation of the air in the decomposition reaction of the foam, Differences between air-filled, nitrogen-blown, and CO$_{2}$-blown foams are investigated, to estimate the importance of allowing air to react with plastic products during decomposition. Results differ somewhat from the conventional EOS, which are generated from values for plastic extrapolated to low densities. [Preview Abstract] |
Thursday, July 2, 2009 4:45PM - 5:00PM |
W2.00005: High-Pressure Range Shock Wave Data for Syntactic Foams J. Ribeiro, R. Mendes, I. Plaksin, J. Campos, C. Capela Syntactic foams [SF] are a porous composite material that results from the mixture of Hollow Glass Micro Spheres [HGMS] with a polymeric binder. Beyond a set of technological advantages over the polymer considered alone, SF present as an essential feature the possibility to control in wide limits the amount, the shape and the size of the porous and by that reason is being used for benchmarking in the area of the shock wave [SW] behaviour of porous materials. In this paper SW loading experiments of SF samples were performed in order to assess the high-pressure range Hugoniot equation of state as a function of the SF initial density. Hugoniot data was assessed coupling the SW velocity within the SF samples with the SW velocity in a reference material or with manganin gauge results. The results obtained present a significant variation with the initial specific mass and can be described with appreciable precision by the Thouvenin/Hofmann model while the concordance between the experimental results and the Gr\"{u}neisen model seems to be very dependent on the Gr\"{u}neisen coefficient values. [Preview Abstract] |
Thursday, July 2, 2009 5:00PM - 5:15PM |
W2.00006: The Response of Dyneema to Shock-Loading David Chapman, Christopher Braithwaite, William Proud Dyneema is a registered trademark of a self-reinforced polyethylene (manufactured by DSM) which is showing great promise as a replacement for brittle-fibre-reinforced epoxies in various dynamic applications. As part of an investigation of its high-rate mechanical properties, we have measured the response of Dyneema under the condition of uniaxial strain during shock-loading. Data on the principal-Hugoniot curve was obtained using in-material manganin stress gauges to measure both longitudinal stress and shock-wave velocity. Off-Hugoniot data was generated using a plate-impact reverberation technique, where a Dyneema sample was contained between two higher impedance copper anvils. Manganin stress gauges mounted on the interface between the Dyneema sample and copper anvils monitored the ring-up of stress in the specimen. Finally, the release curve from a given principal-Hugoniot state was measured using a reverse ballistic impact technique where free-surface velocity was measured using interferometric methods. [Preview Abstract] |
Thursday, July 2, 2009 5:15PM - 5:30PM |
W2.00007: ABSTRACT WITHDRAWN |
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