Q2. A basic flapper/nozzle device is shown in Fig Q3 (not drawn to scale). The pnuematic signal for the input bellows unit is proportional to the measured temperature within the range 0-120℃. The output signal range is to be 20–100 kN/m2.
The characteristic of the input bellows is 5 μm/℃, and the characteristic of the nozzle is 0.2 kN/m2 per μm of flapper movement.
The gain of the device = % change in output / % change in input
Calculate EACH of the following:
(a) the flapper movement at the nozzle for 100% input change;
(b) the resulting change in output;
(c) the gain of the device;
(d) the new setting of ‘y’, the distance from the pivot to the nozzle, to achieve a gain of 0.5;
(e) the output pressure at 75°C with a gain of 0.5 if the output pressure was 40 kN/m2 at a temperature of 30°C.
Q3. A short vertical hollow cylindrical column, 180 mm high and fixed at the base, is 80 mm outside diameter and 10 mm thick. It carries concentrated loads of 9 kN and 5 kN as shown in Fig Q6.
(a) The maximum compressive stress in the column;
(b) The maximum tensile stress in the column.
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