Yan Dong, Pezzulla Matteo, Cruveiller Lilian, Abbasi Arefeh, Reis Pedro M
Flexible Structures Laboratory, Institute of Mechanical Engineering, École Polytechnique Fédérale de Lausanne (EPFL), Vaud, Switzerland.
École Polytechnique, Palaiseau, France.
Nat Commun. 2021 May 14;12(1):2831. doi: 10.1038/s41467-021-22776-y.
Shell buckling is central in many biological structures and advanced functional materials, even if, traditionally, this elastic instability has been regarded as a catastrophic phenomenon to be avoided for engineering structures. Either way, predicting critical buckling conditions remains a long-standing challenge. The subcritical nature of shell buckling imparts extreme sensitivity to material and geometric imperfections. Consequently, measured critical loads are inevitably lower than classic theoretical predictions. Here, we present a robust mechanism to dynamically tune the buckling strength of shells, exploiting the coupling between mechanics and magnetism. Our experiments on pressurized spherical shells made of a hard-magnetic elastomer demonstrate the tunability of their buckling pressure via magnetic actuation. We develop a theoretical model for thin magnetic elastic shells, which rationalizes the underlying mechanism, in excellent agreement with experiments. A dimensionless magneto-elastic buckling number is recognized as the key governing parameter, combining the geometric, mechanical, and magnetic properties of the system.
壳屈曲在许多生物结构和先进功能材料中至关重要，即便传统上这种弹性不稳定性在工程结构中一直被视为一种需避免的灾难性现象。无论如何，预测临界屈曲条件仍是一个长期存在的挑战。壳屈曲的亚临界特性使其对材料和几何缺陷极度敏感。因此，实测的临界载荷不可避免地低于经典理论预测值。在此，我们提出一种稳健的机制，利用力学与磁学之间的耦合来动态调节壳的屈曲强度。我们对由硬磁弹性体制成的加压球壳进行的实验表明，通过磁驱动可调节其屈曲压力。我们为薄磁弹性壳建立了一个理论模型，该模型使潜在机制合理化，与实验结果高度吻合。一个无量纲的磁弹性屈曲数被认为是关键的控制参数，它综合了系统的几何、力学和磁学特性。
