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handbook of modern sensors

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10.4 Bellows, Membranes, and Thin Plates 343<br />

(A)<br />

(B)<br />

Fig. 10.2. (A) Steel bellows for a pressure transducer (fabricated by Servometer Corp., Cedar<br />

Grove, NJ); (B) metal corrugated diaphragm for conversion <strong>of</strong> pressure into linear deflection.<br />

(A)<br />

(B)<br />

Fig. 10.3. Thin plate (A) and membrane (B) under pressure p.<br />

spherically, like a soap bubble. At low-pressure p differences, the center deflection<br />

z m and the stress σ m are quasilinear functions <strong>of</strong> pressure 2 :<br />

z max = r2 p<br />

4S , (10.5)<br />

σ max ≈ S g , (10.6)<br />

where r is the membrane radius and g is the thickness. Stress is generally uniform<br />

over the membrane area.<br />

2 Stress is measured in newtons per square meter.

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