Engineers at the Korea Research Institute of Standards and Science (KRISS) have developed a new ultrasonic sensing technology that can detect structural defects in dangerous environments where traditional inspection methods often fail.
The innovation could help improve safety in industries such as nuclear power, aerospace, and large chemical plants.
The research, published in the journal Mechanical Systems and Signal Processing, introduces a new way to perform non-destructive testing (NDT).
NDT is a widely used inspection method that allows engineers to check the internal condition of structures without damaging them.
Ultrasonic waves are commonly used in these inspections because they can travel through solid materials and reveal cracks, corrosion, or other hidden problems.
However, conventional ultrasonic sensors must usually be attached directly to the surface of the structure being tested.
This requirement creates major challenges in extreme environments.
For example, pipelines in nuclear power plants can reach extremely high temperatures, while chemical storage facilities may contain toxic or corrosive substances.
In these situations, sensors can quickly become damaged, and installing them can be dangerous or even impossible.
Another challenge with existing systems is that many sensors rely on multiple sensing elements arranged around a structure to inspect it from all directions. These segmented sensors often produce wave interference, which can distort the signals and reduce inspection accuracy.
To solve these problems, the KRISS research team developed a new sensor system that uses a waveguide as an intermediate connection between the sensor and the structure being inspected.
A waveguide is a device that can carry waves, such as sound waves, from one location to another.
In the new design, ultrasonic waves travel through the waveguide before reaching the inspection target. This means the sensor itself can be placed safely away from hazardous environments while still sending and receiving ultrasonic signals.
The key innovation of the system lies in the type of vibration generated within the waveguide. The researchers created torsional vibrations—similar to the twisting motion of wringing out a towel—inside a cylindrical waveguide.
These vibrations spread evenly in all directions when they reach the surface being inspected. As a result, the system can scan a full 360-degree area and detect defects from any direction.
The waveguide design is also highly flexible. It can be made from different materials and shaped to match curved surfaces such as pipes or tanks. This adaptability allows the sensor to operate reliably in a wide range of industrial conditions.
Tests of the system showed impressive performance. The sensor achieved about 95 percent uniformity in signal direction, meaning it could inspect structures evenly in all directions.
The strength of the ultrasonic signal was also more than 13 times greater than that produced by conventional segmented sensors. This improvement allows faster scanning of large structures while still providing high-resolution detection of defects.
The researchers believe the technology could greatly improve monitoring of critical infrastructure in extreme environments. It may allow engineers to inspect areas that were previously difficult or impossible to access.
In addition to improving safety, the new system could also reduce costs. Instead of using multiple expensive sensors, engineers could use a single sensor connected to a relatively low-cost waveguide to inspect large areas.
The team also found that the sensor works well in liquid environments, meaning it could be used to inspect large underwater structures.
By helping engineers detect hidden damage earlier and more reliably, the new ultrasonic technology could play an important role in preventing industrial accidents and protecting critical infrastructure.
