Engineering considerations for the development of disk spring stacks for vibration isolation

Coned disk springs exhibit significant nonlinear properties including the quasi-zero stiffness regimes that are useful in isolating equipment at the lower frequency vibrations. However, the stroke of a single disk spring is too low for most applications, and thus springs must be stacked to increase the deflection. Development of such isolator stacks then becomes critical for practical uses. The goal of this article is to identify challenges and engineering considerations in developing such stacks within the practical constraints. For instance, how to appropriately contain the stack without affecting the low-frequency isolation performance. Three designs are analyzed: a retaining ring design, tube and shaft design, and zero Poison’s ratio sleeve design. Disk spring stack protypes with each containment method are built, and force-deflection curves are measured and compared with the standalone stacks. Under quasi-static compression testing, each containment method has minimal effect on the standalone stack force-deflection curve. However, significant advantages of certain methods are found including lateral stability, lateral strength, and degrees of freedom. Lastly, advantages, disadvantages, and appropriate applications for each containment method are summarized, and are demonstrated. Salient contribution of this work is the identification of engineering considerations that would lead to robust or versatile containment designs. This has been overlooked in the scientific literature as the stack containment methods are found to be important in the design of isolation devices.