The selection of actual frequencies for eddy current inspection is based on:

In eddy current testing, the selection of frequencies is influenced by multiple factors that all play a critical role in effectively detecting and characterizing flaws in conductive materials. Understanding these factors is essential for optimizing the inspection process.

The thickness of the material directly affects the skin depth, which is the distance that an electromagnetic wave penetrates into the material before it is significantly attenuated. Lower frequencies provide greater penetration depth, making them suitable for thicker materials. Conversely, higher frequencies are more effective for detecting flaws closer to the surface in thinner materials.

The desired depth of penetration is another important consideration. Depending on the specific application and the type of flaws one aims to detect, the frequency can be adjusted to achieve the necessary depth of inspection. For instance, if deeper subsurface flaws are of concern, lower frequencies would be utilized to ensure that the eddy currents penetrate adequately.

Finally, the required degree of sensitivity or resolution also plays a pivotal role in frequency selection. Higher frequencies generally enhance the ability to detect small defects with better resolution. However, if the primary goal is to locate larger defects or assess overall material integrity, a different frequency might be more appropriate.

The answer encompassing all these factors reflects the complexity and multifaceted nature of frequency selection in eddy current inspections,