A conventional thin homogeneous elastic plate shows no net lateral strain when subjected to a pure bending load. Here, a two-dimensional (2D) metamaterial exhibiting an exotic bending-induced expansion behavior is designed based on the structure unit with a non-symmetric contact under tensile and compressive loads. Expansion behavior was demonstrated in the fabricated 2D metamaterial structures in four-point bending, tension, and compression tests and corresponding simulations. The bending-expansion ratio, defined as the lateral strain times the curvature radius divided by the length of the unit cell, is a non-dimensional parameter depending on the geometry of the structure.

中文翻译：

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具有弯曲诱导膨胀行为的二维机械超材料

传统的薄均匀弹性板在承受纯弯曲载荷时不显示净横向应变。在这里，基于在拉伸和压缩载荷下具有非对称接触的结构单元，设计了一种表现出奇异的弯曲诱导膨胀行为的二维 (2D) 超材料。在四点弯曲、拉伸和压缩测试以及相应的模拟中，在制造的 2D 超材料结构中证明了膨胀行为。弯曲膨胀比定义为横向应变乘以曲率半径除以晶胞长度，是一个无量纲参数，取决于结构的几何形状。