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.