ABSTRACT

There are many applications where it is necessary to provide a passive area in the center of a diaphragm in the form of a boss or rigid center. For example, if the diaphragm is to be used as a pressure-summing device to generate a force, the rigid center is necessary for coupling the data conversion element—usually a rod or linkage pin. To be effective the thickness of the rigid center should be at least 6 times the thickness of the diaphragm. The maximum radial bending stresses for a flat diaphragm with rigid center occur at the outer and inner perimeters and diminish to the inflection circle where a directional reversal of stress takes place. The maximum radial stress for a force-loaded diaphragm with rigid center occurs at the inner perimeter. The smaller deflection of the diaphragm yields much better linearity than the diaphragm without rigid center.