Smart materials are kinds of designed materials whose properties are controllable with the application of external stimuli such as the magnetic field, electric field, stress, and heat. Smart materials whose rheological properties are controlled by externally applied magnetic field are known as magneto-rheological materials. Magneto-rheological materials actively used for engineering applications include fluids, foams, grease, elastomers, and plastomers. In the last two decades, magneto-rheological materials have gained great attention of researchers significantly because of their salient controllable properties and potential applications to various fields such as automotive industry, civil environment, and military sector. This article offers a recent progressive review on the magneto-rheological materials technology, especially focusing on numerous application devices and systems utilizing magneto-rheological materials. Conceivable limitations, challenges, and comparable advantages of applying these magneto-rheological materials in various sectors are analyzed critically, which provides a clear pathway to the researchers in selecting and utilizing these materials. The review starts with an introduction to the elementary description of magneto-rheological materials and their significant contribution in various fields. Following this, different types of the magneto-rheological materials, modeling of the magneto-rheological materials, magneto-rheological material–based devices, and their applications have been extensively reviewed to promote practical use of magneto-rheological materials in a wide spectrum of the application from the automobile to medical device.

This paper presents vibration control of a semi-active seat suspension with a magneto-rheological (MR) fluid damper, which is applicable to commercial vehicles such as large size of trucks. A cylindrical MR seat damper is designed on the basis of the Bingham model of the MR fluid. After manufacturing the seat damper, field-dependent damping force characteristics are experimentally evaluated. A semi-active seat suspension system installed with the seat damper is then constructed and its governing equation of motion is derived. A skyhook controller to reduce vibration level at the driver’s seat is formulated and realized in a closed-loop control fashion. The control responses, such as acceleration transmissibility, are investigated in both frequency and time domains. In addition, a full-vehicle model featuring the proposed semi-active seat suspension is established and its vibration control performances are evaluated via the hardware-in-the-loop simulation (HILS).