Improved Low Frequency Eddy Current Inspection for Cracks Under Installed Fasteners.
Abstract
The purpose of this program was to establish the feasibility of using low frequency eddy current (LFEC) techniques to inspect the second layer of a built up aluminum structure for hole cracking, with the titanium fasteners installed. This program pursued two parallel approaches for low frequency eddy current inspection. One approach was with centered field excitation in the fastener hole. The second approach was with off-center field excitation in the fastener hole. The program consisted of two tasks. The first task was to optimize the probes for both approaches, and involved analysis, design, optimization of probes, and testing of various unique driver/sensor combinations. The second task was to develop inspection techniques with the optimized probes on notched specimens containing flush-head titanium fasteners with appropriate signal processing and display. It has been shown that it is feasible and practical to use LFEC multisegment or circular array probe to detect 0.1 inch radial depth notch underneath 0.25 inch thick aluminum alloy skin, with titanium fasteners in place. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1980
- Accession Number
- ADA098543
Entities
People
- D. T. Mih