Download or read book Multifrequency Eddy Current Detection of Cracks at Fastener Holes with the Fastener Installed written by H. Monty O'Connor and published by . This book was released on 1983 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multifrequency Eddy Current Inspection for Cracks Under Fasteners written by J. H. Flora and published by . This book was released on 1976 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: The experimental evaluation was conducted on two typical wing splice joint configurations used in the C5-A aircraft consisting of two aluminum layers each 3/16 to 1/4 inches thick. Notches simulating cracks were machined in a radial direction extending from the fastener hole and the faying surface between sheets. A digital eddy-current system designed around a PDP-11/40 minicomputer was utilized for the experimental evaluations. The digital system was programmed to generate the signal wave-forms that excite the test coil and perform the function of phase-sensitive detection of response signals that are received from the test coil. Special test coils were designed to induce eddy currents in the aluminum alloy that lies beneath the head of the fasteners. A series of measurements were taken on the wing-splice samples at various frequencies, excitation levels, and phase settings. These data were analyzed using the Automatic Interaction Detector, AID, computer code to indicate initial capabilities of crack detection, and to compare the various operating parameters such as excitation frequency and test coil design.
Download or read book Eddy Current Crack Detection Around Fastener Holes in Multilayer Structures written by Jeremy Scott Knopp and published by . This book was released on 2005 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multifrequency Eddy Current Inspection for Cracks Under Fasteners written by G. H. Wilson and published by . This book was released on 1979 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report describes the second phase of a two-phase program. Phase I, reported in TR-76-209, was directed toward the evaluation and demonstration of multiple frequency eddy-current (MFEC) using wing-splice samples and laboratory instrumentation to detect cracks under titanium and steel fasteners. This Phase II report covers the development evaluation of a prototype MFEC system for field use. The system was built around commercially available micro-computer modules coupled with in-house designed eddy current electronics, an eddy current probe, and a multifunction operator control panel. The system was 'trained' using two C-5A wing panel sections having sawcuts to simulate cracks. Tenth-inch sawcuts at the top of the second layer could be repeatedly detected using a decision algorithm based on a combination of four frequencies. The prototype system was evaluated during July, 1978, as part of the C-5A Structural Evaluation and Inspection Program (SEIP). Of approximately 400 fasteners inspected with the system, one suspect was found and later confirmed with another NDE method. In continued development of the MFEC technique, methods must be investigated which will be tolerant of variations in geometry found around rib stiffeners and single fastener rows. (Author).
Download or read book Improved Low Frequency Eddy Current Inspection for Cracks Under Installed Fasteners written by D. T. Mih and published by . This book was released on 1980 with total page 90 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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).
Download or read book Eddy Current for Detecting Second Layer Cracks Under Installed Fasteners written by William R. Sheppard and published by . This book was released on 1994 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: The detection of second layer Cracks Under Fasteners (CUF) persists as an Air Force Logistics need. This work seeks to extend technology developed for detecting cracks in aluminum alloy substructure below graphite-epoxy skins, to structures with an aluminum first layer. Improvements to the design of the Northrop Low Frequency Eddy Current Array (LFECA) system are identified to improve sensitivity to CUFs in aluminum-over-aluminum structures. The probe core shape, dimensions, and coil configurations were optimized for detection with installed fasteners and metallic skin. A multiparameter analysis algorithm is applied to enable flaw discrimination from centering variations, edge responses and other sources of noise. The study also quantifies the capabilities and limitations of the LFECA system. Eddy current, Low frequency eddy current, Cracks, CUFs, Nondestructive Evaluation (NDE).
Download or read book Detecting Cracks Under Ferrous Fasteners Using the Nortec 30 Eddyscan Fastener Hole Inspection Instrument written by Nolan, R. W and published by North York, Ont. : Defence and Civil Institute of Environmental Medicine. This book was released on 1997 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Nortec-30 Eddyscan Fastener Hole Inspection Instrument was used to detect known fatigue cracks under the heads of alloy steel fasteners installed in 0.258 in. diameter countersunk fastener holes drilled through 0.330 in. pieces of 7075-T651 aluminum alloy plate. It was found that magnetic fields caused by prior magnetization in a majority of ferrous fasteners resulted in large numbers of false indications. When nonferrous or non magnetized ferrous fasteners were used, the Nortec-30 was able to reliably detect relatively small flaws in the holes underneath the beads of these fasteners. Since the rotating coil eddy current technique is dependent upon the magnetic condition of the fastener, the Nortec-30 is not recommended for use with ferrous fastening systems.
Download or read book Aerospace Manufacturing Technology written by and published by Allied Publishers. This book was released on 1997 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Model Assisted Probability of Detection Validation of Eddy Current Inspection for Cracks in Lap Splice Fastener Holes written by and published by . This book was released on 2008 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eddy Current for Detecting Second Layer Cracks Under Installed Fasteners written by and published by . This book was released on 1994 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: Southwest Research Institute developed an eddy current (EC) laboratory breadboard inspection system to detect second-layer cracks around installed fasteners in two-layer airframe structures with the probe positioned on the first layer (outside surface). Probe design considered both cup- and segment-core configurations as exciter coils and various orientations and positions of sensor coils. Highest sensitivity was obtained with a segment-core exciter covering an 85-degree segment with the sensor oriented normal to the specimen surface and placed near the core outer leg. EC data were presented in two-dimensional color images. The goal of detecting a 2.5-mm second-layer flaw through a first-layer thickness of 6.4 mm was achieved in eight of nine specimen configurations which contained simulated cracks. The specimens included structure geometries containing second-layer edges, first-layer edges, adjacent fasteners, different fastener sizes, different flaw orientations around the hole, and fasteners of different materials (titanium and steel). In fatigue crack specimens supplied by WL/MLLP, where adjacent fasteners were spaced more closely and caused interfering signals, flaw detection was more difficult; however, a 2.5-mm flaw was detected through a 4.5-mm first layer by comparing the signal patterns from adjacent holes. Aircraft, Fastener hole, Two-layer structure, Wing, Eddy current, Nondestructive inspection.
Download or read book The Development and Evaluation of an Automated Eddy Current Fastener Hole Scanner written by W. H. THOMPSON and published by . This book was released on 1974 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: UNDER AUTHORITY OF THE AIR FORCE, TWO PROTOTYPE AUTOMATIC EDDY CURRENT SCANNERS WERE DEVELOPED. THE COMPLETED UNITS WERE CAPABLE OF INSPECTING HOLES AS LARGE AS 1 INCH IN DIAMETER AND 4 INCHES DEEP AND AS SMALL AS 5/32 INCH IN DIAMETER WITH A DEPTH OF .050 INCH. INSPECTION OF FATIGUE DAMAGED STRUCTURAL MEMBERS HAS SHOWN THAT CRACKS WITH A SURFACE LENGTH AS SMALL AS .0085 INCH CAN BE DETECTED AND THAT CRACKS WITH A SURFACE LENGTH OF .050 INCH CAN BE DETECTED 90 PERCENT OF THE TIME WITH A 95 PERCENT CONFIDENCE LEVEL. WHERE LAYERS OF MATERIALS ARE PARALLEL, THE CRACK SIZE FOR THE SAME DEGREE OF RELIABILITY WOULD DECREASE.
Download or read book British Journal of Non destructive Testing written by and published by . This book was released on 1976 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Review of Progress in Quantitative Nondestructive Evaluation written by Donald O. Thompson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 2093 pages. Available in PDF, EPUB and Kindle. Book excerpt: These Proceedings, consisting of Parts A and B, contain the edited versions of most of the papers presented at the annual Review of Progress in Quantitative Nondestructive Evaluation held at University of San Diego, San Diego, CA, on July 27 to August 1, 1997. The Review was organized by the Center for NDE at Iowa State University, in cooperation with the Ames Laboratory of the USDOE, the American Society of Nondestructive Testing, the National Institute of Standards and Technology, the Federal Aviation Administration, and the National Science Foundation IndustrylUniversity Cooperative Research Centers. This year's Review of Progress in QNDE was attended by approximately 370 participants from the US and many foreign countries who presented a total of approximately 350 papers. As usual, the meeting was divided into 36 sessions with four sessions running concurrently. The Review covered all phases of NDE research and development from fundamental investigations to engineering applications and inspection systems, and methods of inspection science from acoustics to x-rays. The Review continues to experience some fluctuations in size, mostly under pressure from a decrease in funding for NDE research at the US Federal level, but increased participation from foreign laboratories has more than made up the difference. The Review is ideally sized to permit a full-scale overview of the latest developments in a collegial atmosphere that most participants favor. The opening plenary session this year concentrated on advances in imaging technologies and methodologies that have been made in recent years. Dr. K.
Download or read book Metals Abstracts written by and published by . This book was released on 1983-07 with total page 1250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1979 with total page 1186 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Eddy Current Detection of Pitting Corrosion Around Fastener Holes written by J. H. Heida and published by . This book was released on 1994 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Giant Magnetoresistance Based Eddy Current Probes for Nondestructive Testing written by Teodor Dogaru and published by . This book was released on 2002 with total page 434 pages. Available in PDF, EPUB and Kindle. Book excerpt: ABSTRACT: Detection of deeply buried cracks and of small cracks initiating at edges of metallic parts and structures are among the challenges encountered by the nondestructive testing industry. Solid-state magnetic sensors based on Giant Magneto-Resistance (GMR) and Spin-Dependent Tunneling (SDT) effects have been integrated in eddy current probes that are capable of addressing these difficult problems. Because of their superior sensitivity, small dimensions and low cost, these sensors have been proved effective for detection of deeply buried cracks (up to 25 mm below the surface) using eddy current methods. A problem of great interest in airplane industry that has been successfully addressed in this work is the detection of deep corner cracks around fastener holes in multi-layered aluminum structures. Significant advances in high-resolution metallic profile imaging and corrosion monitoring using the new generation of eddy current probes are reported in this work. Spatial resolution in the range of 100 micrometers has been obtained by using these probes.
