Constant-force pseudoelastic springs and applications thereof

摘要

Pseudoelastic elements are subjected to pre-strains and restrained in order to form springs which exhibit relatively constant force levels over a major fraction of maximum deflection capacity during loading and also during unloading. Pre-straining of pseudoelastic elements subjects them to strains which approach or reach the upper stress plateau of the pseudoelastic stress-strain curve. Loading of said pseudoelastic springs thus produces strains largely corresponding to the upper pseudoelastic stress plateau where strain variations cause relatively small changes in stress. Unloading of said pseudoelastic springs also produces strains largely corresponding to the lower stress plateau of the pseudoelastic stress-strain curve where stress is subject to relatively small changes with strain variations. Said psueodoelastic springs can be used in brush holders which can benefit from a relatively constant level of force as deflections occur due to brush wear.