Abstract: A torsional vibration damper of the type having a hub which carries an outer inertia ring coupled thereto by an elastomer. Supplemental damping is added to the system via the use of dry friction. A broad frequency range of effectiveness is provided by designed non-linearity of the device made possible by the dry friction. A greater broadening of the frequency range of effectiveness is made possible by utilizing a plurality of inertia masses carried by the hub, all mounted on the same elastomer. Elastomeric compression is utilized to spring-load the friction surfaces, providing a series-parallel, elastomer viscous-dry friction damping medium. In multiple mass application the concept of mass interaction is utilized to further determine the dynamic performance of the damper.

Abstract: An apparatus and method for determining the response and performance of a torsional vibration damper. Normally aligned optical patterns are placed on an axial face of the hub and on an axial face of the inertia member. Light is projected on and reflected from both the pattern on the hub and the pattern on the inertia member. Displacement of the hub and inertia member and the phase relationship between the displacements is sensed during rotation by reflected light passed to two photocells. The performance of the damper, including its dynamic response, is computed by comparing the outputs of the two photocells and may be read by meters.