In this paper, the possibility for acquiring dynamic characteristics of pressure sensors is described. A dynamic pressure generator is assembled with two opposing loudspeakers and a confinement ring in-between. The ring has several openings for connection of the evaluated and reference pressure sensors. Frequency, waveform and amplitude control of the generated pressure were achieved by applying an amplified function generator signal to the loudspeakers. Since general-type audio loudspeakers were used, the solution is cost-effective as well. The background of our theoretical model, determination of the mechanical parameters, pressure measurements and arising problems that we found are shown.

The paper presents the prototype of the membrane pressure gauge with optoelectronical conversion. The main parts of the system are polished metal membrane, plastic (PMMA) 2 m long optical fibres, and the box containing optoelectronic components (laser diode module, beam splitter, photodetectors and op. amps). Pressure changes causing membrane displacement modulate the laser beam conducted by incoming optical fibre. Modulated and reflected beam is conducted through the outgoing optical fibre to the optoelectronical assembly where it is converted into the voltage proportional to the pressure. Two different electronic circuits for the compensation of laser diode light beam intensity fluctuation are compared. The calibration characteristic recorded using mercury filled U-tube manometer in the range from 0 to 0.52 × 10⁵ Pa shows accuracy +/- 0.8 % FS.

An iterative method for the reconstruction of the oscillating-pressure measuring signal at the inlet of the small diameter cylindrical tube is presented. This method requires a good mathematical model of the flow phenomena in the tube. The theoretical model of the phenomena and its experimental correction are described. The limitations and the application range of this reconstruction method are discussed.

The paper reports some new results obtained in the theory of Electromagnetic induction flow measurement. These include the extending of the present theory to multiphase application, measurement of dielectric fluid and flow pattern reconstruction.

It is necessary to make constructional changes on the dies for manufacturing of tubular mechanical elements by forward and backward cold extrusion in order to maintain high dimensional precision. The radial elastic deformations are controlled by inserting single or double shrink fit within the die. This arrangement decreases and homogenizes tangential stresses in the die and shrink rings and improve die fatigue life. A conventional way of calculating stress and deformation for this kind problem is Lame Equations. In this study, the effect of dimensional changes of die and shrink rings on the radial deformations occur in the internal surface of the shrink ring, U_rr, is investigated. The diameters of die and shrink rings are investigated in order to maintain preselected diametral tolerances. Under preselected process and design conditions the following results were found; for +0.1 mm. tolerance single die, for the tolerance value of 0.05 - 0.1 mm. single shrink ring and for the tolerance values below 0.05 mm. double shrink rings were necesssary. The theoretical results showed that beyond the radial ratios r₂/r₁ = 4 for single shrink design and r₄/r₁ =7 for double shrink ring design the radial deformation curve, U_rr, becomes asymptotic and an increase in external diameter does not make any change. The results achieved by Lame Equations are compared with those of the Finite Element Method solved by Ansys Programme it is seen that the difference is generally up to 3 %. Also it is predicted that due to the external pressure introduced by shrink rings the radial deformations within the die towards the outer surface is zero. Hence, this results no crack on the outer surface of die and longer fatigue life.