Experimental study on the effect of different shape of orifices of damper piston hole on vibration reduction

Abstract

Dampers play a critical role in vibration-absorbing systems. Achieving optimal ride comfort and stability under varying load and road conditions remains a significant engineering challenge. Conventional dampers typically employ circular straight holes in the piston head and rely on the clearance between the piston head and the cylinder wall, resulting in a constant damping coefficient that may not be suitable for all operating scenarios within the 1–5 Hz frequency range. The present study aims to enhance ride comfort by enabling variation of the damping coefficient without additional energy input. This is accomplished by replacing the standard circular orifice on the piston head with various combinations of convergent, divergent, convergent–divergent, single, and double-tapered oval-shaped orifices, each with different outlet diameters and taper lengths. A single-degree-of-freedom (SDOF) spring–mass–damper system was utilized, incorporating an electrodynamic shaker, accelerometer sensors, a data acquisition system, and LabVIEW software for experimental analysis. Twelve piston heads with different orifice shapes were fabricated using 3D printing to match the diameter and thickness of the piston head used in a two-wheeler rear mono-shock damper. The amplitudes of acceleration and displacement of the base and top plates were analysed to evaluate system performance. Experimental results demonstrate that the double-taper circular-orifice piston-head damper achieved up to a 60% reduction in acceleration and displacement amplitudes at the peak frequency, with substantial reductions at higher frequencies compared to other orifice designs.