Design an‎d Optimization of Acoustic Black Hole Beams Integrated with Mechanical Metamaterials for Vibro-Acoustic Energy Harvesting from Railway Noise

6/2/2026 12:00:00 AM

Abstract: With the expansion of wireless sensors an‎d structural health monitoring systems in industrial environments, providing a sustainable power supply for low-power devices has become a significant challenge. In this context, acoustic sources in railway industries, such as train passage noise an‎d wheel–rail contact noise, offer considerable potential for energy harvesting. In this study, the performance of piezoelectric energy harvesters under acoustic excitation was investigated with the aim of enhancing output power. To this end, the effects of the acoustic black hole (ABH) region an‎d geometric amplifiers including auxetic, honeycomb, an‎d conventional configurations were examined in five different structural arrangements. First, a polynomial regression surrogate function was extracted an‎d validated using simulation data to describe the system behavior. Subsequently, the coefficients of this function were optimized using machine learning techniques to improve the model accuracy. After verifying the accuracy of the surrogate model, geometric optimization was performed using a genetic algorithm with the objective of maximizing the output power. In addition, a parametric study was conducted to validate the optimal values an‎d identify the sensitivity of design parameters in each configuration. Mechanical an‎d electrical analyses were then carried out, an‎d the numerical results were validated through experimental tests. The results demonstrated that the acoustic black hole increased the output power from 31.024 to 72.221 μW an‎d enhanced the strain energy density from 1.17 to 2.52 J/m³. By incorporating conventional, honeycomb, an‎d auxetic amplifiers, the output power further increased to 85.817, 93.013, an‎d 135.47 μW, respectively. The parametric study revealed that the optimal values were consistent with the response trends of the system. Moreover, in the beam containing the acoustic black hole, the truncation length parameter exhibited the highest sensitivity, whereas in the structures equipped with auxetic an‎d honeycomb amplifiers, the amplifier thickness was identified as the most influential design parameter. The best performance was achieved by the structure combining the acoustic black hole with the auxetic amplifier, which yielded approximately a 337% increase in output power compared with the conventional beam. Experimental results also confirmed the validity of the numerical model, with discrepancies between numerical an‎d experimental results ranging from 8% to 11% for output power an‎d from 11% to 14% for resonance frequency. Overall, the integration of the acoustic black hole an‎d auxetic amplifier provides an effective approach for concentrating energy induced by acoustic excitation, improving electromechanical coupling, an‎d enhancing the performance of acoustic piezoelectric energy harvesters.

برداشت‌ انرژي , سياه‌چاله صوتي , آگزتيك , بهنيه‌‌سازي

energy harvesting , acoustic black hole , auxetic , optimization

MohammadHossein Ahmadi

Dr. Younesian