Controlling the position of desiccation cracks using memory effect of paste


Akio Nakahara (Nihon University)


In the case of desiccation cracks of colloidal suspensions, we had demonstrated we can control the formation of crack patterns by showing that dense suspensions (pastes) exhibit memory effects, which means that the paste layer remembers the direction of the horizontal vibration and the flow it has experienced just before the drying process starts, so that the memory determines the *direction* of the future crack propagation. The plasticity of the paste is necessary for the memory effects [1]. However, it was difficult to control the *position* of crack formation in this way. Here we report that combining this method with Faraday waves enables us to control positioning of the cracks. The Faraday waves induced by vertical vibration localize the regions of strong horizontal vibration, so that we can imprint not only the directions but also the positions of the future cracks in the paste [2].
[1] A. Nakahara and Y. Matsuo, J. Phys. Soc. Japan 74 (2005) 1362; Phys. Rev. E 74 (2006) 045102.
[2] H. Nakayama, Y. Matsuo, Ooshida T. and A. Nakahara, Eur. Phys. J. E 36 (2013) 1.

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