Introduction to Power Ultrasound
Ultrasonic waves are mechanical vibrations in solids or fluids. They are a type of mechanical wave that is different from electromagnetic waves. The vibration frequency generally exceeds the audible range of the human ear by 20000 Hz, hence the name ultrasonic waves. The upper frequency limit of ultrasound is generally limited by the signal processing capability of the generator - in some fields, frequencies in the gigahertz range (vibrating more than 1 billion cycles per second) have already been used.
Ultrasound has been widely used in various fields, but for convenience, we generally divide them into two categories: low-power and high-power ultrasound. The main applications of low-power ultrasound include medical imaging (such as scanning unborn fetuses) and non-destructive testing (such as routine crack detection of aircraft structures). Please note that in both cases, ultrasound will not have any significant impact on the scanned object. In contrast, the energy output of high-power ultrasound will be much greater. Our company (FUNSONIC) mainly produces this type of product, but first let's take a look at a set of numbers.
High power applications tend to use lower end frequencies (i.e. from 20kHz to approximately 200 kHz). This is because frequency limits the size of vibrating components. Generally speaking, the lower the frequency, the larger the size, and the higher the power that can be generated. On the contrary, higher frequencies (as well as square waves or step functions containing high-frequency harmonics) are often used for measurement applications, as shorter wavelengths can provide higher accuracy and mechanical stress is not a problem in low-power states.
In order to maximize its effectiveness, high-power ultrasound typically requires the use of as many amplitudes as possible during application. Specifically, the amplitude is continuously increased until certain objects (such as plastics, fabrics, particles) are damaged. The typical amplitude range is from about 5 to 50 micrometers (0.005 to 0.05 millimeters). No matter how you measure it, this may not sound like much, but think about it: an ultrasonic system operating at a frequency of 20 kHz (20000 times per second) and 50 microns moves at a cyclic acceleration of 80000 g (80000 times gravity). Is there anything else on Earth that can rival it?
A small question about amplitude: There is a convention in the ultrasound industry to express vibration amplitude using the term 'peak to peak'. A number that is twice the amplitude defined by physics (i.e. midpoint to peak). Assuming that most of the people reading these pages are not ultrasound experts, in reality, if it is a single peak value and requires peak to peak numbers, then x2 is sufficient.
