Topological metamaterials are a class of engineered materials that exhibit unique mechanical and electromagnetic properties. These materials are designed to have a specific topology, meaning they have a carefully crafted internal structure that gives them the desired properties. One of the key features of topological metamaterial is their ability to manipulate the flow of waves, such as sound waves, electromagnetic waves, and even mechanical waves. This is because the different topological properties of the band gaps that can selectively reflect, transmit, or absorb certain frequencies of waves. In engineering, topological metamaterials have a wide range of potential applications. For example, they can be used to create acoustic cloaks that make objects invisible to sound waves, or to build devices that can selectively filter or amplify certain frequencies of electromagnetic radiation. They can also be used to create lightweight and durable structures for aerospace or automotive applications, or to design sensors that are highly sensitive to mechanical or electromagnetic stimuli. Indeed, the importance of topological metamaterials in engineering lies in their ability to provide unique solutions to some of the most pressing challenges facing modern technology. By manipulating the properties of waves in new and innovative ways, these materials have the potential to revolutionize fields ranging from telecommunications and transportation to healthcare and environmental monitoring.
Topological metamaterials can be combined with structural elements, such as plates, beams, piles and so on. In civil engineering in particular, topological metamaterial plates have the potential to provide innovative solutions to a variety of challenges, such as reducing vibration, enhancing energy absorption, and improving structural resilience. For instance, topological metamaterial plates can be used to design earthquake-resistant structures by controlling the propagation of seismic waves. These plates can be integrated into building foundations, walls, and roofs to reduce the impact of seismic activity and minimize structural damage. Moreover, topological metamaterial plates can be used in soundproofing to create sound barriers that reduce noise pollution from highways, airports, and other sources. These plates can be designed to reflect and absorb specific frequencies of sound, and can be integrated into walls, windows, and ceilings to create quieter indoor spaces. Furthermore, they can be used to design shock absorbers and other energy-dissipating devices that can protect structures from impact and vibration. These plates can be integrated into bridges, buildings, and other structures to enhance their resilience and reduce the risk of damage from extreme events. These materials can have unique properties in construction that allow them to withstand extreme conditions, such as high winds, extreme temperatures, and seismic activity due to their lightweight design and durability.
Topological insulators are a class of materials that have unique electronic properties due to their topological nature. Topological metamaterial and topological insulators are both types of materials that exhibit topological properties. While topological insulators are naturally occurring materials, topological metamaterial are artificial materials designed to exhibit similar properties. In civil engineering, topological insulator-based sensors could be used to monitor structural health and integrity by detecting changes in strain, temperature, or vibration. Moreover, they could be used to harvest energy from sources such as building heating and cooling systems or geothermal energy sources. Topological insulators could potentially be used as a new type of insulation material in building construction. Their high electrical resistivity and thermal conductivity could make them a useful material for insulation applications where high temperatures or electrical fields are present.
In a new study published in the peer-reviewed journal Engineering Structures, Professor Zhifei Shi and PhD candidate Anchen Ni from Beijing Jiaotong University introduced the new concept of topological insulators into plates, enabling the creation of topologically protected interface states of flexural waves. By incorporating this concept into plates, topologically protected interface states of flexural waves can be created, allowing for wave guiding and attenuation simultaneously. They conducted detailed analyses of the unit cell, numerical simulations, and experimental validations to gain insights into the wave guiding and attenuation performance of topological metamaterial plates. Their study demonstrated that the new method can create topologically protected interface states of flexural waves, enabling efficient wave manipulation and potentially overcoming the limitations of bandgap-based metamaterial plates.
To investigate the performance of topological metamaterial plates, Professor Zhifei Shi and Anchen Ni conducted comprehensive simulations in the frequency domain. Low-reflecting boundary conditions marked with blue lines around the model were used to eliminate reflections. An out-of-plane harmonic point source was applied at the left side, while the receiver was placed at the right side. The authors defined transmittance as T=20*lg(A1/A0)(10), where A0 and A1 represent the root mean square of acceleration response at the exciting and receiving points, respectively. They also fabricated and tested two scaled experimental models to prove the wave guiding and attenuation performance of topological metamaterial plates, gaining valuable insights into how this technology can be used for ambient vibration mitigation in civil engineering structures.
In summary, the use of topological metamaterials for wave guiding and damping in civil engineering plates is a promising technology. Incorporating topological insulators into plates can create topologically protected interface states for flexural waves, thus enabling efficient wave manipulation and potentially overcoming the limitations of bandgap-based metamaterial plates. This technology can be used for low-frequency vibration mitigation, energy harvesting, signal detection, and more. In a statement to Advances in Engineering, lead author, Professor Zhifei Shi explained “topological metamaterials are a fascinating class of materials with unique wave manipulation properties that arise from their topological nature. They have the potential to revolutionize many areas of technology and are an exciting area of research for materials scientists, physicists, and engineers.”
Anchen Ni, Zhifei Shi*. Topological metamaterial plates: Numerical investigation, experimental validation and applications. Engineering Structures, Volume 275, Part A, 15 January 2023, 115288