Machine Learning-Driven Design Optimization of Buckling-Induced Quasi-Zero Stiffness Metastructures for Low-Frequency Vibration Isolation

Metastructures, artificial arrangements of micro/macrostructures, possess unique properties and are of significant interest in aerospace, stealth technology, and various other applications. Recent studies have focused on quasi-zero stiffness metastructures, providing an outstanding vibration isolation capability. However, existing methods are constrained to low preloads and lack the consideration of structural analysis, despite their intended use in practical structures. This study introduces metastructures with quasi-zero stiffness characteristics under high preloads by inducing local buckling. An optimization framework combining deep reinforcement learning and finite-element analysis is employed to derive an optimal model that considers both structural safety and quasi-zero stiffness characteristics. To validate the optimization results, quasi-zero stiffness metastructures are fabricated via 3D printing, and compression and vibration experiments are conducted. The fabricated metastructures exhibit quasi-zero stiffness characteristics under a high target preload along with outstanding vibration reduction performance, even in the low-frequency range.

Quasi-Zero Stiffness Vibration Sensing and Energy Harvesting Integration Based on Buckled Piezoelectric Euler Beam

This paper presents a novel quasi-zero stiffness vibration sensing and energy harvesting integration system for absolute displacement measurements based on a buckled piezoelectric Euler beam (BPEB) with quasi-zero stiffness (QZS) characteristics. On one hand, BPEB provides negative stiffness to the system, thus creating a vibration-free point within the system and transforming the absolute displacement measurement problem into a relative motion sensing problem. On the other hand, during the measurement process, the BPEB collects the vibration energy from the system, which can provide electrical energy for low-power relative motion sensing devices and remarkably suppress the frequency range of the jump phenomenon, thereby further expanding the frequency domain measurement range of the sensing system. The research results have shown that this system can measure the absolute motion signal of the tested object in low-frequency vibration with small excitation. By adjusting parameters such as the force-electric coupling coefficient and damping ratio, the measurement accuracy of the sensing system can be improved. Furthermore, the system can convert the mechanical energy of vibrations into electrical energy to power the surrounding low-power sensors or provide partial power. This could potentially achieve self-powering integrated quasi-zero stiffness vibration sensing, offering another approach and possibility for the automation development in wireless sensing systems and the Internet of Things field.

A Highly Sensitive Triboelectric Quasi-Zero Stiffness Vibration Sensor with Ultrawide Frequency Response

Sensors based on triboelectric nanogenerators (TENGs) have gained worldwide interest owing to their advantages of low cost and self-powering. However, the detection of most triboelectric vibration sensors (TVS) is restricted to low frequency, whereas high-frequency vibration signals are successfully measured in recent studies; their sensitivity still requires improvement. Hence, a highly sensitive vibration sensor based on TENG (HSVS-TENG) with ultrawide frequency response is presented. This study is the first to introduce a quasi-zero stiffness structure into the TENG to minimize the driving force by optimizing the magnetic induction intensity and the weight of the moving part. The results show that the HSVS-TENG can measure vibrations with frequencies ranging from 2.5 to 4000 Hz, with a sensitivity ranging from 0.32 to 134.9 V g^-1 . Moreover, the sensor exhibits a good linear response versus the applied acceleration, and the linearity ranges from 0.08 to 2.81 V g^-1 . The self-powered sensor can monitor the running state and fault type of the key components with a recognition accuracy of 98.9% by leveraging machine-learning algorithms. The results reach a new height for the ultrawide frequency response and high sensitivity of the TVS and provide an idea for a follow-up high-resolution TVS.

Research on a nonlinear quasi-zero stiffness vibration isolator with a vibration absorber

A negative stiffness mechanism consisting of a spring and cylinder is proposed, and a grounded dynamic vibration absorber is designed based on a quasi-zero stiffness vibration isolator to constitute the vibration isolator with a vibration absorber system. The range of parameters for attaining zero stiffness is derived from static analysis. The dynamic analysis of the vibration isolator with a vibration absorber system is carried out by a multiscale method, and the amplitude-frequency response equation of the system is obtained. The influence of different system parameters on the amplitude-frequency response is analyzed. The amplitude-frequency response of the quasi-zero stiffness vibration isolator is compared with that of the vibration isolator with a vibration absorber, and the linear and nonlinear analytical solutions of the vibration isolator with a vibration absorber system are also compared. The results show that the designed vibration isolator with a vibration absorber is an ideal choice for low-frequency vibration isolation, with no large resonance peak throughout the system and significantly improved reliability of the system.