The stability and post-bifurcation of a non-linear magnetoelastic film/substrate block is experimentally exploited to obtain active control of surface roughness. The non-intuitive interplay between magnetic field and elastic deformation owes to material and geometry selection, namely a ferromagnetic particle composite film bonded on a compliant passive foundation. Cooperation of the two otherwise independent loading mechanisms-mechanical pre-compression and magnetic field-allows one to bring the structure near a marginally stable state and then destabilize it with either magnetic or mechanical fields. We demonstrate for the first time that the critical magnetic field is a decreasing function of pre-compression and vice versa. The experimental results are then probed successfully with full-field finite element simulations at large strains and magnetic fields. The magnetoelastic coupling allows for reversible on/off control of surface wrinkling under adjustable critical magnetic and mechanical fields, thus this study constitutes a first step towards realistic active haptic and morphing devices.

中文翻译：

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通过略微稳定的磁流变弹性体控制两场表面图案

非线性磁弹性膜/基底块的稳定性和分叉后被实验性地用来获得对表面粗糙度的主动控制。磁场和弹性变形之间的非直观相互作用归因于材料和几何形状的选择，即粘结在柔顺无源基础上的铁磁颗粒复合膜。两种原本独立的加载机制（机械预压缩和磁场）的配合使结构可以达到边缘稳定状态，然后在磁场或机械场作用下使结构不稳定。我们首次证明临界磁场是预压缩的递减函数，反之亦然。然后，在大应变和磁场下，通过全场有限元模拟成功地探究了实验结果。磁弹性耦合允许在可调节的临界磁场和机械磁场下对表面起皱进行可逆的开/关控制，因此，本研究构成了向现实的有源触觉和变形设备迈出的第一步。