A New Technique of Deformation Measurements Based on Microwave Resonant Cavities.

Difficulties with conventional extensometers have led to the development of a new experimental technique to study the behaviour of pre-stressed concrete at cryogenic temperatures. A specially designed coaxial cavity is used as a transducer which relates linearly relative changes in gauge length to relative changes in resonant frequency. An accompanying instrument that automatically measures and displays the resonant frequency of the cavity with sufficient accuracy has also been constructed. This technique has potential applications in more conventional, room temperature civil engineering measurements.