When the ultrasonic medium is not a uniform layered medium (such as biological tissue, human body, etc.), the acoustic impedance of each layer of the medium will reflect the propagating sound wave and form a standing wave. The antinodes and nodes of the standing wave cause pressure and tension. And acceleration changes. Since the masses of particles of different media (such as biomolecules) are different, the vibration speeds caused by pressure changes are different. The pressure changes caused by the relative movement of the media particles are another cause of ultrasonic mechanical effects. The mechanical effect of ultrasonic should be processed (punching, cutting

Cutting, compacting, surface strengthening, welding, cleaning, polishing and removing undesirable films and dirt, etc.), it is also used to accelerate dispersion, homogenization, emulsification, crushing, sterilization and other processes.

Mechanical stirring

Ultrasonic high-frequency vibration and radiation pressure can form effective agitation and flow in gas and liquid. The strong jet and local micro-rush flow generated by the vibration of the cavitation bubble on the solid surface can significantly reduce the surface tension and friction of the liquid, and destroy the surface layer of the solid-liquid interface, thus reaching the level that ordinary low-frequency mechanical agitation cannot reach. effect. This effect is the physical basis for the application of drugs to penetrate people, beauty products to guide people's skin, ultrasonic degassing, and food and cosmetics blending and thinning.

Mutual diffusion

The pressure and high temperature effects of ultrasonic vibration and cavitation are used to promote molecular interpenetration between two liquids, two solids, or between liquid-solid and liquid-gas interfaces, forming new material properties. Ultrasonic welding of metals or plastics, phacoemulsification, cleaning, and atomization can be classified as such effects.

Homogenization

The local shock wave generated after the cavitation bubble is closed can crush the particles in the liquid to make it thin; make the crystal uniform; disperse large and uneven emulsion droplets into tiny uniform drugs (such as medical contrast agents, cancer treatment agents, etc.) ; It may even include the effects of dissolving thrombus.

Cohesion

Ultrasonic vibration can cause the suspended particles in the gas and liquid media to move at different speeds, increasing the chance of collision; or using standing waves to make them tend to the antinodes, so that the condensation process occurs. The flue dust collection and artificial rainfall fall into this category.

Mechanical cutting

Due to the high acceleration of ultrasonic vibration and the acoustic corrosion effect of cavitation, hard and brittle materials (jewels, ceramics, glass, magnetic steel, etc.) can be precisely processed with special shapes.

Crushing effect

The use of high-intensity ultrasound pulses can crush kidney stones and gallstones in the human body without damaging the soft tissues.