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 Inspection Reliability of a Nortec 30 Eddyscan System written by and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The First Joint DoD FAA NASA Conference on Aging Aircraft written by and published by . This book was released on 1998 with total page 1000 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detection Reliability for Small Cracks Beneath Rivet Heads Using Eddy current Nondestructive Inspection Techniques written by Floyd W. Spencer and published by . This book was released on 1998 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced inspection technology that is emerging from the laboratory is generally far superior to the less capable systems around which aircraft inspections are designed. In light of the very conservative nature of these inspection designs, it is apparent that today's advanced technology is being employed at only a fraction of its full potential. In order to assess the full potential of advanced eddy-current inspection technology on representative aircraft applications, the FAA's Airworthiness Assurance Nondestructive Inspection Validation Center (AANC) was tasked to assess the full capability of several advanced systems. The task involved inspections of several rivet skin splices-representative of actual aircraft structure-containing cracks ranging from 0.040-, 0.060-, and 0.080-inch standards, and thresholds were set to the lowest reasonable level for the particular system. The results demonstrated that some of the systems were able to reliably detect cracks as small as 0.040 inch with false call rates remained less than 1%.
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 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 Insight written by and published by . This book was released on 1994 with total page 1116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book FAA NASA International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance written by International Symposium on Advanced Structural Integrity Methods for Airframe Durability and Damage Tolerance and published by . This book was released on 1994 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fibrous Composites in Structural Design written by Edward M. Lenoe and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Fourth Conference on Fibrous Composites in Structural Design was a successor to the First-to-Third Conferences on Fibrous Composites in Flight Vehicle Design sponsored by the Air Force (First and Second Conferences, September 1973 and May 1974) and by NASA (Third Conference, November 1975) which were aimed at focusing national attention on flight vehicle applications of a new class of fiber reinforced materials, the advanced com posites, which afforded weight savings and other advantages which had not been previously available. The Fourth Conference, held at San Diego, California, 14-17 November 1978, was the fi rst of these conferences to be jointly sponsored by the Army, Navy and Ai r Force together with NASA, as well as being the first to give attention to non-aerospace applications of fiber reinforced composites. While the design technology for aerospace applications has reached a state of relative maturity, other areas of application such as mi litary bridging, flywheel energy storage systems, ship and surface vessel components and ground vehicle components are in an early stage of development, and it was an important objective to pinpoint where careful attention to structural design was needed in such applications to achfeve maximum structural performance payoff together with a high level of reliability and attractive economics.
Download or read book Small Fatigue Cracks written by K.S. Ravichandran and published by Elsevier. This book was released on 1999-09-30 with total page 511 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the fully peer-reviewed papers presented at the Third Engineering Foundation Conference on Small Fatigue Cracks, held under the chairmanship of K.S. Ravichandran and Y. Murakami during December 6-11, 1998, at the Turtle Bay Hilton, Oahu, Hawaii. This book presents a state-of-the-art description of the mechanics, mechanisms and applications of small fatigue cracks by most of the world's leading experts in this field. Topics ranging from the mechanisms of crack initiation, small crack behavior in metallic, intermetallic, ceramic and composite materials, experimental measurement, mechanistic and theoretical models, to the role of small cracks in fretting fatigue and the application of small crack results to the aging aircraft and high-cycle fatigue problems, are covered.
Download or read book Advanced Life Analysis Methods written by K. Kathiresan and published by . This book was released on 1984 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume covers the results of experimental evaluation of crack growth analysis methods for attachment lugs which were reported in Vol. II of the final report. These experiments were conducted to assess the damage tolerance of aircraft attachment lugs. The experimental test program included baseline material characterization, crack initiation, residual strength and crack propagation tests. Several loading and geometric complexities were considered in the test program. The types of loading complexities included were constant-amplitude, block spectrum and flight-by-flight spectrum, symmetric and off-axis loadings. Peak stress levels in the lug which were below and above the yield strength of the materials were also included in the test program. The types of geometric complexities considered were straight, tapered, dogbone, clevis and real aircraft lug configurations. Additional geometric complexities considered include lugs with lower thickness and lugs with interference-fit bushings. The experimental results were correlated with the analytical predictions made using methods described in Vol. II of the final report and are presented in this volume. Excellent correlation results were obtained for most of the test cases. In some cases, the developed analytical methods needed some improvements or some new solutions had to be generated. Such efforts were conducted and the refined correlation results are also included in the present volume.
Download or read book The Behaviour of Short Fatigue Cracks written by Keith John Miller and published by . This book was released on 1986 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
