Csir

Philip Wayne Loveday

Jeremy Rex Wallis

Frederik A Koch

David Ronald Jones

Robert Henry Sinclair

Jonathan Du Pre Le Roux

Michael Yuri Shatalov

Johannes Nicolaas Bothma

A system for monitoring the condition of elongate structural elements, for example, railway rails, and a method of designing and manufacturing the system is disclosed. The method includes identifying and selecting suitable modes of propagation and signal frequencies that can be expected to travel large distances through an elongate structural element; designing a transducer that will excite the selected mode at the selected frequency; numerically modelling the transducer as attached to the elongate structural element; validating the transducer design by analyzing a harmonic response of the selected mode of propagation to excitation by the transducer, and manufacturing one or more transducers for use in the system.

System for monitoring the condition of structural elements and a method of developing such a system

Transducer

A strain/electrical potential transducer ( ) includes a rigid base ( ), a rigid beam ( ) hinged to the base ( ) at ( ), an elongate stack ( ) of dielectric substance, e.g. piezoelectric material, generally parallel with the beam ( ) and hinged to the base at ( ), and a rigid link ( ) interconnecting ends of the beam and stack remote from the base ( ). The transducer can be operated as a displacement generator by applying potential difference to the stack ( ) via contacts ( ) to strain the stack ( ) and to cause amplified, transverse displacement as shown at ( ). Conversely, the transducer can be operated as a sensor. Displacement at ( ) causes strain in the stack ( ) which generates a potential difference at the contacts ( ). Composite transducers are disclosed. A manipulating device in the form of an arrangement of displacement generators and use thereof for microscanning are disclosed.

Strain/electrical potential transducer

A displacement generator ( ) has a housing ( ) defining a chamber ( ) containing an incompressible liquid ( ). A port ( ) of the housing ( ) is closed by a movable member ( ). Within the chamber ( ), opposing, convex, flexible walls ( ) form an internal modulating chamber ( ), which optionally contains a compressible gas. Opposed ends of the walls ( ) can be displaced toward and away from each other by a motion transducer, e.g. a stack of ceramic piezoelectric members ( ), respectively to pressurize and depressurize the chamber ( ) and thus to displace the member ( ) to and fro to form an output of the displacement generator.

Generating displacement and theroacoustic refrigerator

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Midrand, South Africa

Philip Wayne Loveday