Finite element analysis of pressure distortion coefficient and piston fall rate in a simple pressure balance

A finite element method (FEM) developed by the University of Cassino and the Istituto di Metrologia "G. Colonnetti" (IMGC, Turin) to optimize the design and use of simple pressure balances was applied while the most important operating and design parameters of the piston-cylinder units were varied. In particular, the influence of size, geometrical uncertainties and superficial roughness on the pressure distortion coefficient and on the piston fall rate was considered. Finally an analysis was carried out using the real clearance profile of the IMGC-100-NNtc unit based on dimensional measurements made at the IMGC. The comparison between the experimental values obtained at the IMGC and the numerical values, of both the pressure distortion coefficient and the piston fall rate, show excellent agreement.