Composite disc springs

The feasibility of replacing steel with composite materials in disc springs (or Belleville washers) is investigated. The objective was to reproduce the identical load/deflection characteristics and the maximum load capacity of the steel disc spring while achieving significant mass savings. Design equations for steel disc springs were modified for a quasi-isotropic composite lay-tip. Several prototype disc springs were manufactured and tested, and compared with the performance of equivalent steel springs. The results show that accurate reproducibility of the steel spring's load-deflection characteristics can be achieved by using composites, with a corresponding mass savings of almost 80%. Other composite disc springs of different geometries were tested so that preliminary observations of the effects of geometric features on load-deflection responses could be made. The failure mode (on overloading the composite spring) consisted of radial fracture arising from the hoop stress as predicted by theory. The results of this study indicate that composites can satisfactorily replace steel in disc springs with significant mass savings. (c) 2007 Elsevier Ltd. All rights reserved.