enginuity

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Designer, deployer, D-damper

A novel rotary damper, designed, patented and manufactured at the Engineering Department, was the outcome of an exercise to test design methods and tools at the Engineering Design Centre (EDC). Rotary dampers are typically used for deployment systems by the aerospace industry, e.g. for solar panels on satellites. ‘The solar panels on spacecraft can be as large as a tennis court,’ explains Stuart Burgess. ‘When solar panels open out in space, they are typically deployed by a spring and there has to be some type of damper in the system to stop excessive acceleration of the appendage and prevent it flying off into space.’

Conceptual design of rotary damper displayed using prelude.

Faced with the task of designing a new type of rotary damper capable of operating in a harsh environment, the design team of Dr Stuart Burgess and Jonathan Khang set to, using some commercial tools which are available to students in the department, and some methods and tools developed in the EDC.

A specification was developed using SpecBuilder, a software tool developed in the department. Having selected material hysteresis damping as the method for dissipating energy (a totally novel principle for rotary dampers), the design was then conceptualised using a commercially available solid modelling system, Prelude.

The prototype contains an outer ring of cantilever springs and an inner rotating carrier which guides eight rollers. During operation, centrifugal acceleration causes the rollers to be forced against the springs and, as they vibrate, energy is dissipated through material hysteresis. Advantages include insensitivity to single point failure and no demand for tight dimensional tolerances.

‘The Cambridge Materials Selector* also proved to be a key tool in the design process,’ explains Stuart Burgess, ‘as we had to come up with a material for the springs which had suitable hysteresis properties. High-density polyethylene (HDPE) emerged as the strong candidate’. The design has been entered for a Design Award in the competition run by the Worshipful Company of Turners.

* Featured in enginuity, issue no 2.

The prototype damper in action (diameter approximately 200mm).

Stop Press

Stuart Burgess and Jonathan Khang were both awarded Bronze Medals for their design in the competition mentioned above. As in most years, no Gold Medal was awarded in 1995 – so the rotary damper won second prize. The last Gold Medal was won in 1993 by Stuart Burgess for another novel design for spacecraft.