Location

Brunswick, ME

Start Date

1-1-1992 12:00 AM

Description

In general, eddy current techniques are suitable for finding surface-breaking flaws in conductors. Subsurface cracks are very difficult to detect due to the skin depth effect. Acoustic techniques are effective at detecting subsurface voids, but cracks immediately beneath the surface are difficult to discriminate from the surface signal. Superconducting QUantum Interference Device (SQUID) magnetometers, very sensitive instruments for measuring DC and low frequency fields, have been used for detection of flaws in conducting objects [1,2,3]. By injecting DC and low frequency AC currents into a brass bar, we have detected a subsurface flaw using a SQUID magnetometer, and shown these data to be consistent with our theoretical calculation.

Book Title

Review of Progress in Quantitative Nondestructive Evaluation

Volume

11A

Chapter

Chapter 4: Sensors and Standards

Section

Eddy Current Arrays and Sensors

Pages

1153-1159

DOI

10.1007/978-1-4615-3344-3_149

Language

en

File Format

application/pdf

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Jan 1st, 12:00 AM

Detection of a Deep Flaw Inside a Conductor Using a Squid Magnetometer

Brunswick, ME

In general, eddy current techniques are suitable for finding surface-breaking flaws in conductors. Subsurface cracks are very difficult to detect due to the skin depth effect. Acoustic techniques are effective at detecting subsurface voids, but cracks immediately beneath the surface are difficult to discriminate from the surface signal. Superconducting QUantum Interference Device (SQUID) magnetometers, very sensitive instruments for measuring DC and low frequency fields, have been used for detection of flaws in conducting objects [1,2,3]. By injecting DC and low frequency AC currents into a brass bar, we have detected a subsurface flaw using a SQUID magnetometer, and shown these data to be consistent with our theoretical calculation.