Non-destructive testing (NDT) is a testing methodology that analyzes a material’s measurement or looks for welding defects without causing any damage to the structure and composition of the original sample. Also called non-destructive examination (NDE), non-destructive inspection (NDI), or non-destructive evaluation (NDE), NDT offers several benefits. Here are the different types of non-destructive testing:
Acoustic Emission Testing
A category of passive non-destructive techniques, acoustic emission testing (AET), works using ultrasound. When there are disruptions in the ultrasound emission as a material is put under pressure, you know that the substance has cracks. You can detect these breaks in emissions by using sensors, which are spread out across the surface of the material sample. Sometimes, when a substance undergoes plasticization due to extreme stress, AET can detect that as well. Several industries also use AET to test the evenness and strength of bridges or to check areas for leaks and active corrosion.
Electromagnetic testing, or ET, utilizes an electric current or magnetic field which is transmitted through the conductive part of the material. Electromagnetic testing can be classified into three types: eddy current testing, alternating current field measurement, and remote field testing.
While eddy current testing makes use of an alternating current coil to introduce an electromagnetic field into the sample, alternating current field measurement and remote field testing deploy a probe to create a magnetic field.
Ground Penetrating Radar
Ground-penetrating radar is a geophysical NDT process that creates radar pulses to be sent through the structure of the material. When the waves are reflected or refracted because of an obstruction, you can detect the various electromagnetic properties of the embedded object.
Laser Testing Method
Laser testing is segmented into three types: holographic testing, laser profilometry, and laser shearography. Holographic testing utilizes a laser beam to detect breaks on the surface of a material. These breaks can be due to heat, pressure, or vibration-related stress. Laser profilometry implements a high-speed rotating laser light source to trace defects such as corrosion, erosion, pitting, and cracks.
Finally, laser shearography deploys a laser light to build an image and then take another image after the sample is put under stress. If there are any differences between the images, you know that the sample has some defects.