Within the area of acoustic metamaterials, the field of tunable acoustic structures has gained a large amount of interest for their ability to adapt to a wide range of frequencies. In this work, we explore the intersection of tunable acoustic structures and additive manufacturing by 4D printing a metamaterial element whose acoustic response can be locally, actively tuned via resistive heating. Contrary to existing, thermally tunable structures, which rely on ambient heating for elastic modulation, the 3D printed structure presented here can be precisely controlled to selectively soften or stiffen only desired areas of the structure. We demonstrate this by tuning the acoustic response of membrane structures since many acoustic metamaterial phenomena utilize membrane geometries. Specifically, we present three geometries of tunable membranes, a structure which decreases frequency response upon heating, a structure which increases frequency response upon heating, and a structure which exhibits non-axisymmetric acoustic mode response from normal incident plane waves.

在声学超材料领域，可调声学结构领域因其适应各种频率的能力而引起了广泛的关注。在这项工作中，我们通过4D打印超材料元件来探索可调谐声学结构与增材制造的交叉点，超材料元件的声学响应可以通过电阻加热进行局部主动调整。与依靠环境加热进行弹性调制的现有热可调结构相反，此处显示的3D打印结构可以精确控制，以仅选择性地软化或硬化结构的所需区域。我们通过调整膜结构的声学响应来证明这一点，因为许多声学超材料现象都利用了膜的几何形状。具体来说，我们介绍了三种可调膜的几何形状，