What phenomenon could lead to a non-linear response in an eddy current testing system?

In eddy current testing, non-linear responses can arise from various factors that affect the interaction between the electromagnetic fields and the conductive materials being inspected.

Temperature variance can impact the conductivity of the material, which in turn alters the eddy currents generated. As the temperature changes, the resistivity of the material can fluctuate, resulting in a non-linear relationship between the applied electromagnetic field and the response measured by the system.

Magnetic field disturbance is another factor that can lead to non-linear responses. Any external magnetic fields present during testing can interact with the eddy currents, causing distortion in the measurements. This interference can complicate the interpretation of data since the true response of the material may not accurately reflect its condition due to these external influences.

Impedance mismatch occurs when the impedance of the coil does not align with the impedance of the material being tested. This mismatch can lead to reflections and signal distortions that disrupt the expected linear relationship between the induced eddy currents and the applied electromagnetic field, resulting in a non-linear system response.

Each of these phenomena contributes to a non-linear behavior in an eddy current testing system, making the response of the testing apparatus complex and sometimes difficult to interpret. Acknowledging that all of these factors can influence the results