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Journal Club Theme of November 2012: Harnessing Instabilities in Response to Stimuli
After a few JClubs focused on elastic instabilities of materials and structures, I would like to continue the exciting discussions on instabilities in a broader context - harnessing instabilities in response to stimuli. Besides mechanical forces and stresses, many stimuli such as temperature, PH, light, electric field, magnetic field and chemical potential can induce complex modes of instabilities in diverse materials and structures. Examples range broadly from Turing patterns for morphogenesis in biology to ferroelectric ceramics used in modern technology. Discovering, understanding, and exploiting these instabilities are of both fundamental and practical importance to science and technology. Here, instead of giving an extensive review of the field, I will introduce our recent works on instabilities of dielectrics in response to electric fields. Comments with examples of instabilities in response to other stimuli would be more than welcome and greatly appreciated.
Figure 1. Evolution (left to right) of a water drop in a dielectric polymer under a ramping electric field [Wang et al, Nature Communications, 3, 1157 (2012)].
It is well known that surfaces and defects of solids can become unstable under mechanical loads, i.e. wrinkling or creasing on surfaces and evolution or cavitation of defects in solids. If we replaced mechanical loads with another stimulus, say electric field, would the surface or defect undergo similar modes of instabilities? How to understand instabilities under coupled physical fields and large deformation? Are these instabilities detrimental or beneficial? I would like to use the following papers to initiate our discussion, and invite Imechanicians to share your thoughts about this field and post relevant works here.
• Qiming Wang, Lin Zhang, Xuanhe Zhao, Creasing to Cratering instability in polymers under ultrahigh electric fields Physical Review Letters, 106, 118301 (2011). Supporting Information Video 1.
• Qiming Wang, Zhigang Suo, Xuanhe Zhao, Bursting Drops in Solids Caused by High Voltages Nature Communications, 3, 1157 (2012). Supporting Information Video 1 Video 2 Video 3.