In the present work, two di erent compositions of Magnetorheological (MR) uid samples with 24 and 30% volume fractions of Carbonyl Iron (CI) particles are prepared. The MR uid samples contain CI particles as a dispersive medium, silicone oil as a carrier uid, and white lithium grease as an anti-settling agent. The e ects of oscillating driving frequency, strain amplitude, magnetic eld, and the percentage of CI particle on the rheological properties of the MR uid samples are presented. The properties of MR uid samples are utilized to design and model the carbon/epoxy composite sandwich beams using the ANSYS Composite Pre-post (ACP) module. The modal, harmonic, and transient analyses are performed on all the modeled sandwich beams to study the in uence of MR uid core thickness, face layer thickness, CI particles volume percentage, and magnetic eld on the vibrational response of the sandwich beams. The present study shows signi cant results in the vibrational response of the composite sandwich beam, which will be more useful for structural applications.