Prof. Dr. Mohamed El-Anwar (Master)

Thesis Title

Construction, Performance Evaluation and Proposals For Upgrading NIS Torque Standard Machine

 

Awarding University and Year

Mechanical Design and Manufacturing-Faculty of Engineering –Cairo University-March 2000

 

Abstract

This thesis deals with the design aspects of the first torque standard calibration machine to be constructed at the National Institute for Standards (NIS). Machine specifications were prescribed to cover the range from 2 Nm to 2 kNm with accuracy of 1×10-4 and relative uncertainty of measurements less than 3×10-4. The first part of the thesis presents the various design ideas of torque calibration machines and justifies the selection of its components from commercially available modules. The selected components for the 2 kNm torque standard machine were then constructed and assembled at NIS. NIS machine performance evaluation results were compared with the corresponding results carried out on the primary standard machines at PTB-Germany and good agreement was obtained. Further, the uncertainty of measurements was found to be located within the expected limit. The second part of the thesis investigates some of the ideas proposed to improve the NIS torque standard machine and upgrade its level. The two main ideas investigated deals with minimizing machine lever weight and with the detection of parasitic forces. Addition of a lever mass system to the NIS machine can improve its accuracy to 1×10-5 and lowers the relative uncertainty of measurement to 5×10-5.  Lever mass system design was proposed and evaluated by means of the finite element method (FEM). Parametric design was employed to minimize the lever weight and a weight reduction of 23% was achieved. A new multi-component force/toque transducer proposed in the literature to detect parasitic axial/shear forces and bending moments arising from shifting of axes and angular misalignment was investigated. The design of the new transducer was made by means of FEM, thus transducer geometry and expected loads were proposed for the NIS torque standard machine.