METHODS OF ANALYZING THE VIBRO-ACOUSTIC BEHAVIOR OF MECHANICAL SYSTEMS IN LOW-FREQUENCY ULTRASONIC RANGE

摘要

The vibration of low-frequency ultrasound is widely used in manufacturing industry, e.g. by drawing of metallic materials with a superposition of ultrasonic vibration. To avoid a possible damage of human health and dissipation of energy, it is necessary to optimize the structure of mechanical systems in order to restrict the vibration in the effective zone and to minimize the acoustic emission. To study the vibro-acoustic behavior of mechanical systems, it is necessary to possess the technique to excite mechanical structures and measure the vibration of their surface and their acoustic emission in the low-frequency ultrasonic range. The frequency for conventional modal analysis is limited to about 5 kHz. Methods are investigated to optimize the vibro-acoustic behavior of mechanical systems in the low-frequency ultrasonic range. A special developed shaker is used to excite mechanical structures over a wide frequency range up to 30 kHz and the vibration of the surface is measured by a laser-vibrometer. The method of sound intensity is applied to locate the source of the acoustic emission up to the 1/3-octave-band of 20 kHz. These methods have been verified by studying the vibro-accoustic behavior of the components of a tube drawing machine with superposition of ultrasonic vibration.