Demonstration of topological boundary modes in elastic systems has attracted a great deal of attention over the past few years due to its unique protection characteristic. Recently, second-order topological insulators have been proposed in manipulating the topologically protected localized states emerging only at corners. Here, we numerically and experimentally study corner states in a two-dimensional phononic crystal, namely a continuous elastic plate with embedded bolts in a hexagonal pattern. We create interfacial corners by adjoining trivial and non-trivial topological configurations. Due to the rich interaction between the bolts and the continuous elastic plate, we find a variety of corner states of and devoid of topological origin. Strikingly, some of the corner states are not only highly-localized but also tunable. Taking advantage of this property, we experimentally demonstrate asymmetric corner localization in a Z-shaped domain wall. This finding could create interest in exploration of tunable corner states for the use of advanced control of wave localization.

由于其独特的保护特性，弹性系统中拓扑边界模式的证明在过去几年中引起了极大的关注。最近，已经提出了二阶拓扑绝缘体来操纵仅在角落出现的受拓扑保护的局域态。在这里，我们通过数值和实验研究二维声子晶体中的角状态，即具有六角形图案嵌入式螺栓的连续弹性板。我们通过连接平凡和非平凡的拓扑配置来创建界面角。由于螺栓和连续弹性板之间的丰富相互作用，我们发现了各种没有拓扑起源的角状态。引人注目的是，一些角落状态不仅高度局部化，而且是可调的。利用这一特性，我们通过实验证明了 Z 形畴壁中的非对称角定位。这一发现可能会引起人们对探索可调谐角状态以使用波定位的高级控制的兴趣。