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    Volume 38, Issue 5 (September 2015)

    Special Issue Paper

    Visualizing Kinematics of Dynamic Penetration in Granular Media Using Transparent Soils

    (Received 11 September 2014; accepted 29 October 2014)

    Published Online: 2015

    CODEN: GTJODJ

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    Abstract

    This paper describes a new method for quantitative analysis of dynamic penetration into granular media. The method is based on refractive index matching used to produce transparent synthetic soils. First, a procedure referred to as the embedded plane technique is introduced, to overcome limitations with laser illumination in high-speed photography. The technique consists of seeding an embedded plane with opaque particles sandwiched within the transparent soil to visualize in-plane granular kinematics. Details of sample preparation are presented, and other issues related to rapid penetration into index-matched media are discussed. High-speed image acquisition is introduced for transparent soils, and relevant target illumination techniques are described. Finally, improved digital image correlation methods are introduced and used to derive displacement fields. Shear and volumetric strains are then calculated. Analyses performed on acquired images are used to illustrate the applicability of these novel index-matching methods to the study of low-velocity penetration into granular media. The data illustrates that, for impact velocities considered in this study, the majority of lateral displacements during penetration are contained to approximately four projectile diameters from the penetration axis. Vertical displacements extend several penetrator diameters ahead of the penetrator. Moreover, penetration is accompanied by significant vertical afterflow. Finally, a region of dense sand forms ahead of the penetrator with a conical shape, which travels with the penetrator during penetration.


    Author Information:

    Omidvar, Mehdi
    Polytechnic School of Engineering, New York Univ., New York, NY

    Doreau Malioche, Jeanne
    Ecole Nationale des Travaux Publics de l’Etat, Vaulx-en-Velin,

    Visiting Scholar, New York Univ., New York, NY

    Chen, Zhibo
    Polytechnic School of Engineering, New York Univ., New York, NY

    Iskander, Magued
    Polytechnic School of Engineering, New York Univ., New York, NY

    Bless, Stephan
    Polytechnic School of Engineering, New York Univ., New York, NY


    Stock #: GTJ20140206

    ISSN:0149-6115

    DOI: 10.1520/GTJ20140206

    Author
    Title Visualizing Kinematics of Dynamic Penetration in Granular Media Using Transparent Soils
    Symposium ,
    Committee D18