All‐Polarized Elastic Wave Attenuation and Harvesting via Chiral Mechanical Metamaterials

Materials with target load plateaus offer the potential for developing innovative vibration suppression and isolation systems for applications such as satellite platforms, submarines, and electric vehicles. However, implementing these materials can pose significant challenges. In this study, stair‐stepping mechanical metamaterials with programmable load plateaus are presented, which are created via a three‐level (unit, module, and 3D object) construction strategy. The strategy inspired by the inverse design concept achieves tunability in the number and properties of load plateaus within the force–displacement profiles of the metamaterials. This approach even yields appealing stair‐stepping response patterns, as validated by experiments and finite element simulations. Promisingly, programming the unit from its initial configuration to a “zero stiffness” configuration enables these metamaterials excellent vibration isolation performance. Furthermore, two reversible methods are proposed for switching among various unit configurations, namely shape memory programming and supporting payload. This innovative design strategy for programmable load plateaus opens up new possibilities for creating metamaterials with customized force–displacement responses. It also provides opportunities to incorporate multimodal vibration isolation capabilities into precision devices.

Stair‐Stepping Mechanical Metamaterials with Programmable Load Plateaus

Zeng,

Liu,

et al. 2024

Investigating Static and Dynamic Behaviors in 3D Chiral Mechanical Metamaterials by Disentangled Generative Models

Park,

Noh,

Shin

et al. 2024

Chiral mechanical metamaterials with engineered asymmetric structures have garnered significant interest owing to their potential for manipulating mechanical waves and unconventional mechanical properties. Although several design methodologies have made significant strides in the design and discovery of chiral mechanical metamaterials, 3D designs that incorporate multiple mechanical characteristics remain largely unexplored and the static and dynamic properties of these structures have not received sufficient attention. Here, an innovative approach is introduced for the inverse design of 3D chiral mechanical metamaterials with desired static and dynamic properties, leveraging streamlined shapes to enable a versatile design. By employing conditional generative adversarial networks (c‐GANs), the desired mechanical properties are targeted by focusing on both wave attenuation and stress distribution under compression and shear loading. 3D chiral mechanical metamaterials with additive manufacturing are fabricated to demonstrate the performance of the proposed c‐GAN. Experimental investigations show that the generated structures exhibited a wide range of wave attenuation properties, low stress concentrations, and a variety of stress‐strain curve profiles including nonlinear stiffness, demonstrating their effectiveness in achieving the desired mechanical characteristics. This research offers significant advancements in the on‐demand design capabilities of metamaterials and their applications.

An All‐Polarized Elastic Topological Metamaterial for Ultrasonic Energy Conveying and Harvesting

Chen,

Fan,

Zhu

et al. 2024

Microelastic topological metamaterials (METMs) are of great use in the robust conveying and harvesting of high‐frequency ultrasonic energies. However, current METMs only hold topological edge states of a single flexural mode, restricting their capacity to convey ultrasonic energies of other polarized elastic waves. Moreover, the potential of METMs for ultrasonic energy harvesting remains unexplored. To address these challenges, an all‐polarized elastic topological metamaterial (AETM) is developed, capable of simultaneous conveying and harvesting of ultrasonic energies from elastic waves of all polarizations. This AETM supports broadband topological edge states for both out‐of‐plane and in‐plane modes, enabling the robust conveying of ultrasonic energies from all‐polarized elastic waves. Subsequently, by integrating the AETM with a piezoelectric energy harvester, efficient harvesting of ultrasonic energies conveyed by the AETM is achieved. Notably, the developed AETM with structural simplicity can be easily integrated into micro‐electromechanical systems (MEMSs) for on‐chip ultrasonic wave communication and energy harvesting. This work advances the development of topological metamaterials that can concurrently convey and harvest ultrasonic energies from all‐polarized elastic waves, offering significant potential for various MEMS applications.