Non-destructive testing (NDT) is a non-invasive technique used to detect defects and damages in materials to ensure material integrity and safety. In NDT inspection, strain testing (ST) is a widely

 used technique that provides accurate information about strain distribution and helps us to understand the performance and durability of materials. In this paper, we will discuss the principles, 

applications, and latest technological advances of strain testing in NDT.

Principle

Strain testing (ST) is a technique based on the principles of deformation and load strain. When a material is subjected to an external load, deformation and strain of the material occurs. 

Strain testing evaluates the performance and stability of a material by measuring the strain distribution on the surface or inside the material. The main principle of strain detection is to use strain 

sensors to monitor the deformation information of the material in real time. Strain sensors can be realized by resistive, capacitive, optical, etc., of which resistive strain sensors are the most 

commonly used one. It works by utilizing the resistance sheet on the strain sensor to cause changes in the resistance value when the material is subjected to strain, and accurate strain 

distribution information can be obtained by measuring these changes.

Applications

Environmental and infrastructure monitoring: Strain detection plays an important role in the monitoring of infrastructure such as bridges, buildings and transmission lines. By monitoring the 

strain distribution of structures in real time, damage and deformation can be detected in time so that repair measures can be taken to ensure their safety and reliability.

Aerospace engineering: strain detection is widely used in the aerospace field. Through strain monitoring of key components such as airplane wings, rocket engines and spacecraft, potential 

structural problems can be found and repaired in advance to ensure the flight safety of the aircraft.

Automotive industry: In the process of automobile manufacturing and testing, strain detection can help monitor the strength and stiffness of the body structure. By analyzing the strain 

distribution, the car structure can be optimized and designed to improve the safety and ride comfort of the car.

Latest technological advances

In recent years, with the continuous development of sensor technology, strain detection technology has also received a series of innovations. Here are some of the latest technological advances:

Flexible electronic skin sensors: This new type of sensor is highly flexible and stretchable, and can be affixed to any surface to achieve strain monitoring of complex structures.

Micro- and nanotechnology-based strain sensors: The application of micro- and nanotechnology in the field of strain sensors offers new possibilities for high-sensitivity, high-resolution strain 

detection.

Infrared thermography combined with strain detection: By combining infrared thermography and strain sensors, it is possible to realize contactless thermal strain monitoring and improve the 

accuracy and efficiency of strain detection.

Conclusion.

Strain testing is one of the important techniques in non-destructive testing, which provides accurate information about strain distribution and helps us to understand the performance and durability of materials. It has a wide range of applications in environmental and infrastructure monitoring, aerospace engineering, and the automotive industry. As the latest technology continues to advance, strain testing will play an important role in many more areas, providing us with more reliable and safer materials and structures.