There is an art to effective spring design. It can be very difficult to achieve the desired stiffness behaviour, especially when the available space is restricted and the deflection geometry hard to control.
For certain applications, it may be possible to consider using the repulsive force between magnets as an alternative to conventional springs. One such application area might be in providing people with energy return mechanisms for walking: spring heels, in other words. Various systems exist already but these tend to be complex, expensive and vulnerable to damage.
Today’s invention is to create a number of simple, articulated hinges (of the type used to support domestic doors). Each of these would be equipped with two plates of neodymium magnetic material. It’s possible to show that for heel-sized slabs of such magnet, the repulsive force between plates with opposite polarity would peak at about 500N. The 1-degree of freedom hinge would allow the springback behaviour to be controlled.
Although the impact force of landing on a single heel can be as much as six times body weight (say 6000 N) with a couple of hinges per foot a noticeable extra springiness would be experienced during normal walkng -resulting in less fatigue for eg soldiers, police officers, shop staff and post office workers.
The springiness could be disabled temporarily, if necessary, by flapping the hinges into the fully-open position with magnetic poles at maximal distance from each other.