Bulletin of the American Physical Society
2005 14th APS Topical Conference on Shock Compression of Condensed Matter
Sunday–Friday, July 31–August 5 2005; Baltimore, MD
Session C5: Focus Session: Failure Wave I |
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Chair: Dennis Grady, Applied Research Associates Room: Hyatt Regency Constellation F |
Monday, August 1, 2005 11:00AM - 11:30AM |
C5.00001: Failure waves in shock-compressed glasses Invited Speaker: The failure wave is a network of cracks that are nucleated on the surface and propagate into the elastically stressed body. It is a mode of catastrophic fracture in an elastically stressed media whose relevance is not limited to impact events. In the presentation, main properties of the failure waves are summarized and discussed. It has been shown that the failure wave is really a wave process which is characterized by small increase of the longitudinal stress and corresponding increments of the particle velocity and the density. The propagation velocity of the failure wave is less than the sound speed; it is not directly related to the compressibility but is determined by the crack growth speed. Transformation of elastic compression wave followed by the failure wave in a thick glass plate into typical two-wave configuration in a pile of thin glass plates confirms crucial role of the surfaces. The latter, as well as specific kinematics of the process distinguishes the failure wave from a time-dependent inelastic compressive behavior of brittle materials. The failure wave is steady if the stress state ahead of it is supported unchanging. Mechanism of this self-supporting propagation of compressive fracture is not quite clear as yet. On the other hand, collected data about its kinematics allow formulating phenomenological models of the phenomenon. In some sense the process is similar to the diffusion of cracks from a source on the glass surface. However, the diffusion-like models contradict to observed steady propagation of the failure wave. Analogy with a subsonic combustion wave looks more fruitful. Computer simulations based on the phenomenological combustion-like model reproduces well all kinematical aspects of the phenomenon. [Preview Abstract] |
Monday, August 1, 2005 11:30AM - 11:45AM |
C5.00002: The Dynamic Behaviour of Filled-Glass D.D. Radford, K. Tsembelis, W.G. Proud A series of plate impact experiments has been performed to assess the dynamic behaviour of a filled-glass (Schott SF-57) in both longitudinal and lateral orientations. Information was obtained for the Hugoniot curve and dynamic shear stress properties using manganin gauges. High-speed photography was also utilised to obtain qualitative information on the kinetics of failure. Results are compared and contrasted against published data on other filled-glasses. [Preview Abstract] |
Monday, August 1, 2005 11:45AM - 12:00PM |
C5.00003: Failure Wave in DEDF and Soda-Lime Glass During Rod Impact Dennis Orphal, Thilo Behner, Volker Hohler, Charles Anderson, Douglas Templeton Investigations of glass by planar, and classical and symmetric Taylor impact experiments reveal that failure wave velocity U{\_}F depends on impact velocity, geometry, and the type of glass. U{\_}F typically increases with impact velocity to between $\sim $1.4 C{\_}S and C{\_}L (shear and longitudinal wave velocities, respectively). This paper reports the results of direct high-speed photographic measurements of the failure wave for gold rod impact from 1.2 and 2.0 km/s on DEDF glass (C{\_}S = 2.0, C{\_}L =3.5 km/s). The average rod penetration velocity, u, was measured using flash X-rays. Gold rods eliminated penetrator strength effects. U{\_}F for gold rod impact on DEDF is $\sim $ 1.0-1.2 km/s, which is considerably less than C{\_}S. The increase of u with impact velocity is greater than that of U{\_}F. These results are confirmed by soda-lime glass impact on a gold rod at an impact velocity of 1300 m/s. Similar results are found in``edge-on-impact'' tests; U{\_}F values of 1.4 km/s and 2.4-2.6 km/s in soda-lime glass are reported for W-alloy rod impact, considerably less than C{\_}S (3.2 km/s) [1,2]. [1] Bless, et. al.(1990) AIP Proc. Shock Comp. Cond. Matter---1989, pp. 939-942 (1990) [2] E. L. Zilberbrand, et. al. (1999) Int. J. Impact Engng., 23, 995-1001 (1999). [Preview Abstract] |
Monday, August 1, 2005 12:00PM - 12:15PM |
C5.00004: Shock Wave and Fracture Propagation in Water Ice by High Velocity Impact Masahiko Arakawa, Kei Shirai, Manabu Kato In order to clarify the elementary processes of impact disruption, we made impact experiments of water ice at the impact velocity of 3.6 km/s and conducted simultaneous observation of shock wave and fracture propagation in it by means of ultra-high speed photography. We observed a spherical shock wave propagating with the velocity of 4.4-3.5 km/s from the impact point and a reflection wave from the free surfaces. A region in which HEL (Hugoniot elastic limit) followed the elastic precursor wave, expanded with a velocity of 3-2.5 km/s until the pressure fell below 240 MPa. Below that pressure, a damage region appeared after 0.8-3 $\mu$s of the passage of precursor wave. In this region, dynamic shear strength of water ice was estimated to be 21 MPa. At the front of damage region, a wavy feature appeared and grew up radial cracks. Below 80 MPa, the several radial cracks proceeded toward the rear surface and broke the sample before tensile fracture caused by reflection waves from an antipodal point became visible. Therefore, the main mechanism to make the largest fragment is considered to be the radial crack growth rather than a spallation at the rear. [Preview Abstract] |
Monday, August 1, 2005 12:15PM - 12:30PM |
C5.00005: Impact Studies with Glass Bars Rodney Russell, Stephan Bless, Tim Beno In these bar impact tests, steel plates struck glass bars at about 300 m/s. Compressive failure waves were observed propagating from the projectile face. There were also failure waves in the tensile region produced by shock reflection from the free end of the bar. Measurement of the velocity of the free end of the bar produced an estimate of the tensile strength in this 1-D stress geometry. It was substantially less than the tensile strength of intact glass in 1-D strain. There was a central region of the bar in which fracture occurred very late or not at all. Material was recovered from the different fracture regions, and the nature of the fragments is compared. Modeling with the JH-2 glass model did not reproduced the observed failure regions. [Preview Abstract] |
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