Eddy Current Testing

Depth of Penetration Versus Frequency Chart

With this interactive chart, the material is first selected or a material conductivity value is entered. This will produce the line that shows the relationship between the frequency and one standard depth of penetration for the chosen material or conductivity. The user can then click on the line at a position that corresponds to a particular frequency to determine the value for one standard depth of penetration at that frequency. Alternately, the user can click on the line at a position that corresponds to a specific depth of penetration to obtain the frequency that will produce this depth.

Depth of Penetration Calculator

This calculator allows the user to input the test frequency, material conductivity and magnetic permeability to calculate the the value of one standard depth of penetration in inches or milliliters. The phase lag is also shown graphically.

Impedance and Ohm's Law Calculator

In this applet, users can see how the current and voltage of a circuit is affected by impedance. The applet allows the user to vary inductance (L), resistance (R), voltage (V) and the current (I).

Maxwell-Wien Bridge Calculator

This Maxwell-Wien Bridge calculator often is used to measure unknown inductance in terms of calibrated resistance and capacitance.

Ohm's Law Calculator

In this calculator, users are able to determine the voltage, resistance, and current of a circuit according to Ohm's Law.

Phase Angle Calculator

This calculator can be used to determine the phase angle between the resistive component and the inductive and capacitance components of the impedance in an AC circuit.

Resonance Frequency Calculator

This calculator can be used to determine the resonant frequency of an eddy current probe.

Simple Probe Design Calculator

The following applet may be used to calculate the effect of the inner and outer diameters of a simple probe design on the probe's self inductance. Dimensional units are in millimeters.

Ultrasonic Testing

Acoustic Impedance Calculator

This applet allow the user to compare two materials and "see" how they reflect and transmit sound energy. The red arrow represents energy of the reflected sound, while the blue arrow represents energy of the transmitted sound. The reflected energy is square of the difference divided by the sum of the acoustic impedances of the two materials.

Beam Spread Calculator

This calculator allows the user to calculate the beam spread angle which represents a falling of of sound pressure (intensity) to the side of the acoustic axis of one half (-6 dB) as a function of transducer parameters radius and frequency and as a function of acoustic velocity in a medium.

Crack Tip Diffraction (Down for Repairs)

The height a of cracks can be determined by the tip diffraction method. The principle echo comes from the base of the crack and can easily be found and used to locate the position of the flaw. A second, much weaker echo comes from the tip of the crack and is displaced forward in time from the main echo by delta-t. Once the difference in time is know (dt), it can be plugged into the equation to arrive at the length of the crack.

Field Zone Calculator

For a piston source transducer of radius (a), frequency (f), and velocity (V) of a liquid or solid medium, the applet allows the calculation of the near/far field zone.

Reflection and Transmission Coefficients

Formulation for acoustic reflection and transmission coefficients (pressure) are shown in this calculator. Different materials may be selected or you may alter the material velocity or density to change the acoustic impedance of one or both materials. The red arrow represents reflected sound, while the blue arrow represents transmitted sound.

Snell's Law

Snell's Law is a basic equation that describes how sound is refracted and converted to different wave modes as it passes from one material to another. This calculator can be used to calculate refracted angles the critical angles for various material combinations.

Ultrasonic Measurement of Texture

The following applet may be used to calculate ODC's W400, W420, and W400 from Lamb wave velocities propagating at 0°, 45° and 90° with respect to the rolling direction. First choose the material. This assigns the correct elastic constants c_{11}, c_{12}, c_{44}, and density for the cubic material being investigated. Next enter the "measured" Lamb wave velocities.

Wavelength, Frequency and Velocity

This applet shows a longitudinal and transverse wave. The direction of wave propagation is from left-to-right and the movement of the lines indicate the direction of particle oscillation. The equation relating ultrasonic wavelength, frequency, and propagation velocity is included at the bottom of the applet in a reorganized form.