Multiple parameter eddy current nondestructive testing device using plural transformation rotators to resolve each parameter

Abstract

Abstract AN EDDY CURRENT DEVICE FOR MEASURING MULTIPLE PARAMETER VARIABLES OF A SAMPLE COMPRISES A TEST COIL AND SIGNAL GENERATOR MEANS FOR APPLYING A MULTIDIMENSIONAL EXCITATION SIGNAL TO THE COIL AND MAGNETICALLY COUPLING THE COIL TO THE SAMPLE. A SIGNAL EXPANDER EXPANDS THE OUTPUT SIGNAL FROM THE TEST COIL INTO N DESCRIPTORS REPRESENTATIVE OF THE OUTPUT SIGNAL. N-1 LIKE TRANSFORMATION ROTATORS ARE PROVIDED, EACH ROTATOR INCLUDING A PAIR OF INPUTS AND TWO GANGED SINE-COSINE POTENTIOMETERS ROTATIONALLY DISPLACED NINETY DEGREES WITH RESPECT TO EACH OTHER AND CONNECTED VIA OPERATIONAL AMPLIFIERS AND A SUMMING AMPLIFIER TO PROVIDE FROM THE TRANSFORMATION ROTATOR A FIRST OUTPUT E1=X COS 0-Y SIN 0 AND A SECOND OUTPUT E2=X SIN 0+Y COS 0 WHERE X=AN INPUT SIGNAL APPLIOED TO ONE OF THE ROTATOR INPUTS, Y=AN SIGNAL APPLIED TO THE OTHER OF THE ROTATOR INPUTS, AND 0=THE VARIABLE ROTATIONAL ANGLE OF THE GANGED POTENTIOMETER. EACH INPUT OF ONE OF THE TRANSFORMATION ROTATORS IS CONNECTED TO AN ASSOCIATED ONE OF THE SIGNAL DESCRIPTORS, THE REMAINDER OF THE SIGNAL DESCRIPTORS EACH BEING CONNECTED TO AN ASSOCIATED ONE INPUT OF THE REMAINDER OF THE TRANSFORMATION ROTATORS. THE OTHER INPUT OF EACH OF THE REMAINDER OF THE TRANSFORMATION ROTATORS IS CONNECTED TO AN OUTPUT OF A PRECEDING ASSOCIATED TRANSFORMATION ROTATOR. AN OSCILLOSCOPE DISPLAYS IN THE FIRST AND SECOND OUTPUTS E1 AND E2 OF THE LAST TRANSFORMATION ROTATOR TO PROVIDE A DISPLAY OF ONE PARAMETER VARIABLE OF THE TEST SAMPLE.

Inventors

• 👤 Clarence R Wandling
• 👤 Hugo L Libby

Bibliographic Details