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25 results on '"Aldrin, J. C."'

1. Ultrasonic Phased Array Inspection for an Isogrid Structural Element with Cracks

Author

Roth, D. J, Tokars, R. P, Martin, R. E, Rauser, R. W, Aldrin, J. C, and Schumacher, E. J

Subjects
Quality Assurance And Reliability
Abstract

In this investigation, a T-shaped aluminum alloy isogrid stiffener element used in aerospace applications was inspected with ultrasonic phased array methods. The isogrid stiffener element had various crack configurations emanating from bolt holes. Computational simulation methods were used to mimic the experiments in order to help understand experimental results. The results of this study indicate that it is at least partly feasible to interrogate this type of geometry with the given flaw configurations using phased array ultrasonics. The simulation methods were critical in helping explain the experimental results and, with some limitation, can be used to predict inspection results.

Published
2010

2. Ultrasonic Phased Array Simulations of Welded Components at NASA

Author

Roth, D. J, Tokars, R. P, Martin, R. E, Rauser, R. W, and Aldrin, J. C

Subjects
Acoustics
Abstract

Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increasing role in the future for nondestructive evaluation in order to better understand the physics of the inspection process, to prove or disprove the feasibility for an inspection method or inspection scenario, for inspection optimization, for better understanding of experimental results, and for assessment of probability of detection. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles. Keywords: nondestructive evaluation, computational simulation, ultrasonics, weld, modeling, phased array

Published
2009

3. Ultrasonic Phased Array Inspection Simulations of Welded Components at NASA

Author

Roth, D. J, Tokars, R. P, Martin, R. E, Rauser, R. W, Aldrin, J. C, and Schumacher, E. J

Subjects
Quality Assurance And Reliability
Abstract

Comprehensive and accurate inspections of welded components have become of increasing importance as NASA develops new hardware such as Ares rocket segments for future exploration missions. Simulation and modeling will play an increased role in the future for nondestructive evaluation in order to better understand the physics of the inspection process and help explain the experimental results. It will also help to prove or disprove the feasibility for an inspection method or inspection scenario, help optimize inspections, and allow to a first approximation limits of detectability. This study presents simulation and experimental results for an ultrasonic phased array inspection of a critical welded structure important for NASA future exploration vehicles.

Published
2009

4. Case Study for New Feature Extraction Algorithms, Automated Data Classification, and Model-Assisted Probability of Detection Evaluation (Preprint)

Author

COMPUTATIONAL TOOLS INC GURNEE IL, Aldrin, J. C., Knopp, J. S., COMPUTATIONAL TOOLS INC GURNEE IL, Aldrin, J. C., and Knopp, J. S.

Abstract

This paper explores feature extraction algorithms for crack characterization in eddy current inspection of fastener sites. A novel feature extraction method fitting approximate models to data associated with geometric part features addressing adjacent fastener sites and panel edges are developed. Data classification methods in the circumferential direction around fastener sites are developed to better characterize fatigue cracks with improved noise invariance. Model-assisted probability of detection results are presented highlighting the benefit of automation in NDE., The original document contains color images. All DTIC reproductions will be in black and white. Submitted to be published in the Proceedings of the 33rd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE) Conference 2006.

Published
2006

5. Aging Aircraft NDE: Capabilities, Challenges, and Opportunities (Preprint)

Author

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE, Lindgren, E. A., Knopp, J. S., Aldrin, J. C., Steffes, G. J., Buynak, C. F., AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE, Lindgren, E. A., Knopp, J. S., Aldrin, J. C., Steffes, G. J., and Buynak, C. F.

Abstract

U.S. Air Force aircraft are managed by Damage Tolerance Assessment (DTA) and Nondestructive Evaluation (NDE) plays a critical role in insuring their flight safety. This paper provides an overview of current NDE capabilities for aircraft structures. The potential migration to Condition-Based Maintenance (CBM) will require NDE to evolve from detection of defects to characterization of their location and size. This represents multiple significant challenges as aircraft have many material and geometry factors that complicate this analysis. This paper provides a strategy to resolve these factors., The original document contains color images. All DTIC reproductions will be in black and white. Submitted for publication in the Proceedings of the 33rd Annual Review of Progress in Quantitative Nondestructive Evaluation (QNDE) Conference 2006.

Published
2006

6. Investigation of a Model-Assisted Approach to Probability of Detection Evaluation (Preprint)

Author

AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE, Knopp, J. S., Aldrin, J. C., Lindgren,, E., Annis, C., AIR FORCE RESEARCH LAB WRIGHT-PATTERSON AFB OH MATERIALS AND MANUFACTURING DIRECTORATE, Knopp, J. S., Aldrin, J. C., Lindgren,, E., and Annis, C.

Abstract

This paper presents a model-assisted probability of detection (MAPOD) study for inspection of a two-layer airframe structure. Eddy current measurements for varying crack length around fastener holes in a two-layer aluminum structure are studied using both experimental and model-generated data. New statistical algorithms are used to calculate the probability of detection. Good agreement was achieved between empirical and model-assisted approaches., Prepared in collaboration with Computational Tools, Inc., Gurnee, IL and Statistical Engineering, Palm Beach Gardens, FL. Presented at the Annual Review of Progress in Quantitative Nondestructive Evaluation (33rd), QNDE 2006, held in Portland, OR on 30 Jul-4 Aug 2006. The original document contains color images. All DTIC reproductions will be in black and white.

Published
2006

17. Efficient Solution of Electromagnetic Scattering Problems Using Spatial Decomposition Algorithms.

Author

Knopp, J. S., Sabbagh, H. A., Aldrin, J. C., Murphy, R. K., Sabbagh, E. H., Hoffmann, J., and Steffes, G. J.

Subjects
INTEGRAL equations, ELECTROMAGNETISM, SCATTERING (Physics), DECOMPOSITION method, ALGORITHMS, FINITE element method
Abstract

This paper introduces spatial decomposition algorithms to the volume integral method, which will enable the integral equation method to efficiently solve electromagnetic scattering problems where the scatterer extends across several layers or multiple scatterers exist in multiple layers. Model comparisons with the finite element methods are used validate the approach. Studies of typical aging aircraft eddy current inspection problems are conducted using the new formulation. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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18. Numerical Studies of Eddy Current NDE for Small Crack Detection around Fasteners in Multi-Layer Structures.

Author

Knopp, J. S. and Aldrin, J. C.

Subjects
*CRYSTALLOGRAPHY, *PHYSICAL sciences, *PHYSICS, *ULTRASONICS, *EUCLID'S elements, *SOLIDS
Abstract

A series of numerical studies using validated models are presented investigating the influence of probe design and geometric flaw parameters on the eddy current measurement response for the inspection of cracks around fastener holes in multi-layer structures. Multiple quantitative features of the eddy current data were evaluated. The goal of this study is to demonstrate the influence of these design parameters on the ability to resolve the flaw characteristics in the measurement data. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
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19. Numerical and Experimental Study of Eddy Current Crack Detection around Fasteners in Multi-Layer Structures.

Author

Knopp, J. S., Aldrin, J. C., KO, R. T., and Sabbagh, H.

Subjects
*EDDY currents (Electric), *HOLES, *NONDESTRUCTIVE testing, *AIRFRAMES, *ELECTRONIC probes, *TESTING
Abstract

Previous work on the detection of cracks around fastener holes in multi-layer structures using eddy current NDE has met with some success; however, challenges remain in detecting smaller corner cracks while minimizing false call rates. To address this issue, a 3D model was developed for this problem and successfully validated with experimental data. Using this model, a series of numerical studies were performed to identify potential features for defect classification. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2004
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20. Model and methodology for crack detection on a cylindrical hole containing an elastic insert.

Author

Aldrin, J. C. and Achenbach, J. D.

Subjects
*HOLES, *NONDESTRUCTIVE testing
Abstract

This paper investigates the possibility of crack detection for holes containing elastic inserts. A BEM model was formulated for the scattering response of an incident shear wave transducer signal by a cylindrical hole with a radial notch, an elastic insert, and a stiffness interface between the hole and the insert. Through simulated and experimental studies, certain interface conditions were identified for which significant interface waves can be generated and subsequently used for inspection purposes. [ABSTRACT FROM AUTHOR]

Published
2002

21. Refined detection of cracks in weep holes using spatial signal variation.

Author

Aldrin, J. C. and Achenbach, J. D.

Subjects
*AIRPLANE equipment, *SURFACE defects, *NONDESTRUCTIVE testing
Abstract

In earlier work, an automated protocol was considered to detect bottom cracks in weep holes. During experimentation, this protocol was found to produce some false calls and miss certain small cracks. In this paper, a technique is presented which examines the variation in the A-scan signals as the transducer is incrementally moved along the wing surface. The advantage of this B-scan classification technique is its ability to detect superimposed signals independently from the shape of the pulse. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2001

22. Detection of cracks in weep holes using neural networks.

Author

Aldrin, J. C., Cheng, A., Achenbach, J. D., Andrew, G. A., and Mullis, R. T.

Subjects
*CRACKING of concrete, *ARTIFICIAL neural networks, *ULTRASONIC transducers
Abstract

Weep holes are incorporated in the risers of wing structures in C-141 aircraft to allow fuel to be properly distributed during flight. Two types of fatigue cracks have been observed emanating from weep holes, top cracks that emanate upward and bottom cracks that propagate toward the wing surface. A new approach using creeping Rayleigh waves has been shown to be successful in detecting top cracks in weep holes. The focus of this paper is the development of a robust automated protocol for the detection of both top and bottom cracks in weep holes. A numerical technique was developed using the boundary element method (BEM) to calculate simulated waveforms for reflection and backscattering of ultrasound from weep holes with top or bottom cracks. The simulations were validated by comparison with experimental results. From parametric studies of this model, a robust protocol incorporating both the pulse echo and pitch catch creeping Rayleigh wave signals from top-cracks was defined. Protocols incorporating neural networks were developed for both top and bottom crack classification. A complete automated procedure for crack detection was successfully trained with both simulated and experimental data and was verified with experimental data for the expected variation in weep hole size and crack length. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2000

23. Ultrasonic Phased Array Testing for an Isogrid Structural Element with Cracks.

Author

Roth, D. J., Tokars, R. P., Martin, R. E., Rauser, R. W., Aldrin, J. C., and Schumacher, E. J.

Subjects
ALUMINUM alloys, AEROSPACE planes, STRENGTH of materials, NONDESTRUCTIVE testing, SIMULATION methods & models, ULTRASONICS, AERONAUTICAL systems engineering
Abstract

In this investigation, a T-shaped aluminum alloy isogrid stiffener element used in aerospace applications was tested with ultrasonic phased array techniques. The isogrid stiffener element had various crack configurations emanating from bolt holes. Computational simulation methods were used to mimic the experiments in order to help understand experimental results. The results of this study indicate that it is at least partly feasible to interrogate this type of geometry with the given discontinuity configurations using phased array ultrasonics. The simulation methods were critical in helping explain the experimental results and, with some limitation, can be used to predict testing results. [ABSTRACT FROM AUTHOR]

Published
2010

24. Ultrasonic Phased Array Testing Simulations of Welded Components at NASA.

Author

Roth, D. J., Tokars, R. P., Martin, R. E., Rauser, R. W., Aldrin, J. C., and Schumacher, E. J.

Subjects
ULTRASONIC testing, NONDESTRUCTIVE testing, WELDED joints, SPACE vehicles
Abstract

Comprehensive and accurate tests of welded components have become increasingly important as NASA develops new hardware, such as Ares rocket segments, for future exploration missions. Simulation and modeling will play an increased role in the future of nondestructive testing in order to better understand the physics of the testing process and help explain the experimental results. It will also help to prove or disprove the feasibility of a test technique or scenario, help optimize testing, and allow, to a first approximation, determination of limits of detectability. This study presents simulation and experimental results for ultrasonic phased array testing of a critical welded structure important for NASA future exploration vehicles. [ABSTRACT FROM AUTHOR]

Published
2009

25. Forward models for extending the mechanical damage evaluation capability of resonant ultrasound spectroscopy.

Author

Goodlet BR, Torbet CJ, Biedermann EJ, Jauriqui LM, Aldrin JC, and Pollock TM

Abstract

Finite element (FE) modeling has been coupled with resonant ultrasound spectroscopy (RUS) for nondestructive evaluation (NDE) of high temperature damage induced by mechanical loading. Forward FE models predict mode-specific changes in resonance frequencies (Δf R ), inform RUS measurements of mode-type, and identify diagnostic resonance modes sensitive to individual or multiple concurrent damage mechanisms. The magnitude of modeled Δf R correlate very well with the magnitude of measured Δf R from RUS, affording quantitative assessments of damage. This approach was employed to study creep damage in a polycrystalline Ni-based superalloy (Mar-M247) at 950°C. After iterative applications of creep strains up to 8.8%, RUS measurements recorded Δf R that correspond to the accumulation of plastic deformation and cracks in the gauge section of a cylindrical dog-bone specimen. Of the first 50 resonance modes that occur, ranging from 3 to 220kHz, modes classified as longitudinal bending were most sensitive to creep damage while transverse bending modes were found to be largely unaffected. Measure to model comparisons of Δf R show that the deformation experienced by the specimen during creep, specifically uniform elongation of the gauge section, is responsible for a majority of the measured Δf R until at least 6.1% creep strain. After 8.8% strain considerable surface cracking along the gauge section of the dog-bone was observed, for which FE models indicate low-frequency longitudinal bending modes are significantly affected. Key differences between historical implementations of RUS for NDE and the FE model-based framework developed herein are discussed, with attention to general implementation of a FE model-based framework for NDE of damage., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Published
2017
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