This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/ This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI 10.1109/ACCESS.2021.3134267, IEEE Access VOLUME XX, 2021 1 Date of publication xxxx 00, 0000, date of current version xxxx 00, 0000. Digital Object Identifier 10.1109/ACCESS.2017.Doi Number Magnetorheological Elastomer Based Flexible Metamaterials Coupler for Broadband Longitudinal Vibration Isolation: Modelling and Experimental Verification (October 2021) Abderlahman Ali 1 , Ayman M. H. Salem 2 , Asan G.A. Muthalif 3* , Rahizar Ramli 4 , and Sabariah J Julaihi 5 1,3 Department of Mechanical and Industrial Engineering, College of Engineering, Qatar University, Doha, Qatar 2,4,5 Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur, Malaysia Corresponding author: * Asan G.A. Muthalif (e-mail: drasan@qu.edu.qa). ABSTRACT Longitudinal vibrations due to different external excitations are omnipresent in almost every machine, eventually leading to unplanned downtime, and in some cases, catastrophic failures. The passive approach to isolate such vibration has some limitations. Magnetorheological elastomers (MREs) typically consist of micron-sized ferrous particles dispersed in an elastomeric matrix. Its rheological properties, such as the viscosity and dynamic modulus, can be altered when subjected to a magnetic field. Thus, magnetorheological elastomers have drawn significant attention from researchers due to their versatility in vibration control applications. In this study, an MRE-based metamaterial coupler is fabricated for broadband vibration attenuation. The vibration control performance of the proposed model is investigated in terms of its transmissibility factor. Sine sweep vibration testing is used to examine the transmissibility factor for single, double, and triple-layer MRE metamaterial couplers accompanied by different activation scenarios. The results reveal that the stiffness of the MRE layers increases with the strength of the applied magnetic field. Utilizing more than one layer of MRE increases the ability to isolate longitudinal vibration at different frequency bands. The maximum reduction curves achieved by single, double, and triple-layer MREs are approximately 84.5%, 97%, and 99.6%, respectively. The findings of this study demonstrate that the proposed MRE-based metamaterial couplers can attenuate vibrations at broadband frequencies. INDEX TERMS Metamaterials, Multi-layered magnetorheological elastomer, Vibration isolation, transmissibility factor. I. INTRODUCTION Mechanical systems in various engineering applications are prone to vibrations. Such vibrations are due to different external excitations and are omnipresent in almost every type of machinery. Vibrations are undesired as they can accelerate machine wear, consume excessive power, result in severe deformations, and ultimately lead to catastrophic failures and unplanned downtime. Therefore, vibration isolation techniques have become an essential part of the research field [1-2]. The main objective is the reduction of the interconnections between the source of vibration and the equipment. There are three main techniques to reduce the dynamic effect of vibrations: passive, active, and semi-active systems. Passive isolation systems use the natural properties of a spring and a damper to reduce vibrations and are efficient at mitigating high-frequency vibrations. However, they have limitations in low-frequency due to their natural resonance. Active isolation systems use integrated control systems to improve low-frequency performance. Semi-active isolation systems are intermediate between active and passive and combine the advantages of both methods [3-5]. Exploring the system transmissibility ratio is one way to quantify the vibration imparted to the system. The transmissibility of a system is defined as the ratio of the output to the input, and it is self-evident that the transmissibility must be less than one to reduce the system vibration effectively.