Zhang Yingchao, Huang Weicheng, Liu Mingchao, Yu Jing, Gao Huajian
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore.
Applied Mechanics Laboratory, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
Sci Adv. 2025 May 16;11(20):eadw1259. doi: 10.1126/sciadv.adw1259. Epub 2025 May 14.
Symmetric snap-through buckling, although both theoretically achievable and practically advantageous, has remained rare in bistable systems, with most studies favoring asymmetric snapping due to its lower energy barrier. Previous observations of symmetric snapping have been limited to high loading rates. In this work, we present a universal strategy to achieve symmetric snapping under quasi-static conditions by designing magnetization (M)-interface patterns that effectively suppress asymmetric modes. A simplified theoretical model demonstrates that this behavior results from the interplay between pitchfork and saddle-node bifurcations, with predictions validated through simulations and experiments using hard magnetic elastomers. Resisting forces generated by multiple M-interfaces counteract asymmetric snapping, enabling distinct symmetric configurations. Extending this approach to higher-order symmetric snapping, we uncover a quasi-linear scaling law between critical fields and snapping order. These findings establish a robust framework for designing snapping systems with enhanced control and predictability, as demonstrated by a mechanical-magnetic snapping switch, paving the way for advanced applications in precision engineering and magnetic-mechanical actuation.
对称快速翻转屈曲，尽管在理论上是可行的且在实际应用中具有优势，但在双稳态系统中仍然很少见，大多数研究倾向于非对称翻转，因为其能量势垒较低。先前对对称翻转的观察仅限于高加载速率。在这项工作中，我们提出了一种通用策略，通过设计有效抑制非对称模式的磁化强度（M）-界面图案，在准静态条件下实现对称翻转。一个简化的理论模型表明，这种行为是由叉形分岔和鞍结分岔之间的相互作用引起的，通过使用硬磁弹性体的模拟和实验验证了预测结果。多个M-界面产生的阻力抵消了非对称翻转，从而实现了不同的对称构型。将这种方法扩展到高阶对称翻转，我们发现了临界场与翻转阶数之间的准线性比例定律。这些发现为设计具有增强控制和可预测性的翻转系统建立了一个稳健的框架，如一个机械-磁翻转开关所示，为精密工程和磁机械驱动中的先进应用铺平了道路。
