Bulletin of the American Physical Society
15th APS Topical Conference on Shock Compression of Condensed Matter
Volume 52, Number 8
Sunday–Friday, June 24–29, 2007; Kohala Coast, Hawaii
Session J3: Inelastic Deformation III |
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Chair: Dennis Grady, Applied Research Associates Room: Fairmont Orchid Hotel Plaza I |
Tuesday, June 26, 2007 3:45PM - 4:00PM |
J3.00001: Damage-Failure Transition: Dynamic Crack Branching, Fragmentation, Failure Wave Oleg Naimark, Oleg Plekhov, William Proud, Sergey Uvarov Damage-failure transition as specific type criticality is studied both theoretically and experimentally to link behavior of nonlinear system ``solid with mesodefects'' with generation of collective modes of mesodefects (microcracks, microshears) and subjection of crack dynamics, fragmentation statistics and failure wave generation to evolution of these modes. It is shown that scenario of crack dynamics (transition from steady state to branching regime), different types of fragmentation statistics depending on imposed energy density, failure wave generation are the consequence of symmetry dropping related to blow-up collective modes of damage localization kinetics. High resolution experiments for recording of crack dynamics in preloaded PMMA plate, shock wave and damage dynamics in fused quartz for Taylor tests, correlation analysis of stress phase portraits supported theoretical results concerning the nature of qualitative changes of fragmentation statistics and failure wave generation related to resonance excitation of mentioned collective modes. [Preview Abstract] |
Tuesday, June 26, 2007 4:00PM - 4:15PM |
J3.00002: Failure Kinetics in Borosilicate Glass During Rod Impact Dennis L. Orphal, Charles E. Anderson, Jr., Thilo Behner, Volker Hohler, Matthias Wickert, Douglas W. Termpleton At the last shock physics conference [1], failure front and penetration velocities as functions of impact velocity for gold rods into lead glass (5.19 g/cm3) were presented. Similar experiments have been completed for a borosilicate glass (2.2 g/cm3). Data are obtained by visualizing simultaneously failure propagation in the glass with a high-speed camera and rod penetration with flash radiography. At a given impact velocity, the velocity of the failure front is significantly higher during early penetration than during steady-state penetration of the rod. For steady-state penetration, the failure front velocity is considerably less than the shear wave velocity of the glass. It was found that the ratio of average failure front velocity to rod penetration velocity decreases with increasing impact velocity (vp) in the range of vp = 0.4 to 2.8 km/s. As a consequence, the distance between the rod tip and the failure front is reduced with increasing vp. [1] Orphal DL, Behner Th, Hohler V, Anderson CE Jr, and Templeton DW, ``Failure wave in DEDF and soda-lime glass during rod impact,'' Shock Compression of Condensed Matter-2005, (M. D. Furnish, et al., Eds.), 1391-1394, AIP Conf. Series 845, Melville, NY, 2006. [Preview Abstract] |
Tuesday, June 26, 2007 4:15PM - 4:30PM |
J3.00003: Failure and Penetration Response of Borosilicate Glass During Short-Rod Impact Charles E. Anderson, Jr., Dennis L. Orphal, Thilo Behner, Volker Hohler, Matthias Wickert, Douglas W. Termpleton The failure characterization of brittle materials like glass is of fundamental importance in describing the penetration resistance against impact of projectiles. A critical question is whether this failure front remains ``steady'' after the driving stress is removed. That is, does failure propagate similar to a wave propagating without a driving force, or is it failure kinetics-based with a slow down or a halt after the stress is removed? A test series with short gold rods (D = 1 mm, L/D 5 - 11) impacting borosilicate glass (D = 21mm, L = 60 mm) was carried out to investigate this fundamental question. For the experiments the reverse ballistic method was used and the impact and penetration process was observed simultaneously with five flash X-rays and a 16-picture high-speed optical camera. Very high measurement accuracy was established to ensure reliable results. Impact velocities from 1 km/s to 2 km/s were investigated. Results show that the failure front induced by rod impact and penetration does arrest (come to a standstill) after the rod is totally eroded inside the glass. [Preview Abstract] |
Tuesday, June 26, 2007 4:30PM - 4:45PM |
J3.00004: An interacting micro-crack damage model for brittle failure: Experiments and Modeling Bhasker Paliwal, Kaliat T. Ramesh, James W. McCauley Experimental observations using high-speed photography, on a transparent polycrystalline ceramic undergoing compressive loading* have demonstrated that the interaction among the growing micro-cracks has a profound influence on the failure behavior of brittle materials, particularly under dynamic loading. We model the failure process with distributed inhomogeneities subjected to varying strain rates and pressure. Interactions among the cracks is modeled by means of a `crack-matrix-effective medium' approach in which the cracks experiences a stress field different from that acting on isolated cracks. Load induced damage in the material is defined as a scalar crack density parameter whose evolution is a function of the existing flaw distribution and the crack growth dynamics. The model provides a natural prediction of a peak stress and also of a transition strain rate, beyond which the compressive strength increases dramatically with the imposed strain-rate. The influences of the crack growth dynamics, flaw distribution, imposed strain-rate and confining pressure on the constitutive response and the damage evolution are also studied..$^{\ast }$B. Paliwal, K.T. Ramesh, J.W. McCauley, J. Amer. Ceram. Soc.(2006). [Preview Abstract] |
Tuesday, June 26, 2007 4:45PM - 5:00PM |
J3.00005: Damage Fingers in Brittle Transparent Ceramics Michael Grinfeld, Todd Bjerke, Daniel Casem, Pavel Grinfeld New experimental, theoretical, and numerical results related to dynamic failure in brittle transparent solids are presented. Several penetration experiments with transparent glasses and ceramics show that failure fronts have an extremely rough morphology, including appearance of spikes and cracks. The suggested thermodynamic theory allows the appearance of the roughness as a manifestation of morphological instability of failure fronts. The novel theoretical results are based on the thermodynamic paradigm suggested in the references below. [Preview Abstract] |
Tuesday, June 26, 2007 5:00PM - 5:15PM |
J3.00006: Phenomenological description of the failure waves in glasses G.I. Kanel, A.S. Savinykh, G.V. Garkushin, S.V. Razorenov, A. Rajendran A combustion-like model of failure wave has been developed accounting for new data on the response of intact and comminuted glass to longitudinal and bulk compression and release. The bulk compressibility of soda-lime glass was measured by the mixture method. It has been found that, under uniaxial compression, the Poisson's ratio increases up to the value close to 0.5. The strong dependence of the Poisson's ratio on deviatoric stress results in increase of average unloading impedance of cracked glass that explains small value of the recompression signal. On the other hand, experiments with step-like compression demonstrate decreased impedance for further compression of cracked glass. The failure wave model includes equations of state of intact and comminuted glass, a criterion of compressive fracture, and an equation that relates damage accumulation rate to the damage parameter gradient. Computer simulations with this model reproduce well all details of observed behavior of the glass. [Preview Abstract] |
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