High enough to hear the sound - what is the use of ultrasound?
The sound with frequencies above 20,000 Hz is commonly known as ultrasound. As the frequency increases, the wavelength becomes shorter. In most solid materials, sound waves travel at speeds ranging from 1,000 to 10,000 meters per second. Ultrasound can reach frequencies up to 10⸠to 10¹² Hz, which falls within the microwave range of the electromagnetic spectrum. By leveraging the propagation characteristics of ultrasound in solids and the effects of cavitation and radiation pressure from high-power ultrasound, a variety of useful applications have emerged, such as ultrasonic cutting, grinding, and drilling.
**1. Non-Destructive Testing**
In industrial settings, parts like metal components may develop internal cracks or voids due to material flaws or manufacturing processes. These defects can weaken the structure or cause leaks, posing serious risks. To detect these without damaging the part, non-destructive testing methods are used, including X-ray, electromagnetic, and ultrasonic techniques. Among these, ultrasonic testing is one of the most common. It works by sending pulses into the material; if there are defects, the signals reflect back. By analyzing the time it takes for the signal to return, the depth and location of the defect can be determined. This method, known as reflection detection, is widely used in quality control. Another technique, transmission flaw detection, involves sending a signal through the material and measuring its intensity on the other side. For bonded structures, acoustic impedance measurements help identify weak joints. In large infrastructure projects like highways and railways, ultrasonic sensors are often embedded to monitor structural integrity over time.
**2. Ultrasonic Hardness Testing**
This method involves pressing an ultrasonically vibrating transducer against the surface of a material. The indentation caused by this contact affects the transducer’s resonance frequency. The harder the material, the less the frequency changes, allowing hardness to be measured based on the frequency shift.
**3. Thickness Measurement**
By applying ultrasound to a material, the thickness can be determined using resonance or pulse echo methods. When a material resonates at a specific frequency, knowing the speed of sound in that material allows accurate thickness calculations. This method is widely used in industries where precision is crucial.
**4. Liquid Level Measurement**
Ultrasonic sensors are used to measure the level of liquids in tanks. They work by emitting a sound pulse and measuring the time it takes to return after reflecting off the liquid surface. Lower-frequency ultrasound is typically used to reduce absorption in air or liquid.
**5. Ultrasonic Thermometer**
For high-temperature environments like steam turbines or combustion chambers, traditional thermometers are impractical. An ultrasonic thermometer measures temperature by calculating the speed of sound in the medium, as sound velocity is directly related to temperature.
**6. Flow Rate Measurement**
In pipelines, ultrasonic flow meters use either time difference or Doppler effect principles to measure fluid flow. Two transducers send and receive sound waves, and the difference in arrival times helps determine the flow rate.
**7. Ultrasonic Viscometer**
Viscosity measurement using ultrasound involves analyzing how a transducer vibrates in a liquid. The resistance caused by the liquid's viscosity alters the transducer’s electrical properties, allowing viscosity to be calculated.
**8. Phacoemulsification**
High-powered ultrasound can mix immiscible liquids like oil and water, creating stable emulsions. This technique is used in food, pharmaceutical, and fuel industries to improve mixing efficiency and reduce pollution.
**9. Ultrasonic Cleaning**
Complex mechanical parts with small holes or narrow channels can be cleaned effectively using ultrasound. The cavitation caused by ultrasonic waves removes dirt and debris from surfaces, making cleaning more efficient.
**10. Ultrasonic Pulverization**
Instead of traditional grinding, ultrasonic waves can break down materials into finer particles. This process produces more uniform and smaller particles than conventional methods.
**11. Ultrasound Tin**
To solder aluminum, which has a strong oxide layer, ultrasonic vibrations can remove the oxide film, allowing tin to adhere properly. This technique is especially useful in high-tech manufacturing.
**12. Ultrasonic Humidifier**
These devices use high-frequency sound waves to break water into fine mist, increasing humidity without raising room temperature. The tiny droplets remain suspended in the air for longer periods.
**13. Ultrasonic Welding**
This technique is used to join metals or plastics without heat. It is particularly useful for delicate components and is widely applied in electronics and aerospace industries.
**14. Ultrasonic Motor**
Unlike traditional motors, ultrasonic motors convert electrical energy into mechanical vibrations, offering advantages like high torque, precise control, and compact design. They are increasingly used in robotics and precision instruments.
Shanghai Janetec Electric Co., Ltd. , https://www.janetecelectric.com