Research and Test Apparatus

Milliard Ltd. have produced a machine for ‘fatiguing’ a metal test specimen by means of sound waves instead of the more conventional mechanical strains. Ultrasonic power is generated electronically and applied to a magneto‐striction transducer. The vibrations produced are increased in amplitude by a step‐up velocity transformer and applied to the specimen, a short rod of the metal under test. The specimen is designed to be resonant at the applied frequency, so that standing waves are produced. At the point of minimum movement the strain is at a maximum, and eventually the specimen breaks there. The strains can be as much as 30 tons/sq. in. and can be applied at a rate of up to 20,000 times per second.