Chatham, IL, United States
Chatham, IL, United States

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Aldrin J.C.,Computational Tools Inc. | Coughlin C.,TRI Austin | Forsyth D.S.,TRI Austin | Welter J.T.,Air Force Research Lab
AIP Conference Proceedings | Year: 2014

Progress is presented on the development and implementation of automated data analysis (ADA) software to address the burden in interpreting ultrasonic inspection data for large composite structures. The automated data analysis algorithm is presented in detail, which follows standard procedures for analyzing signals for time-of-flight indications and backwall amplitude dropout. ADA processing results are presented for test specimens that include inserted materials and discontinuities produced under poor manufacturing conditions. © 2014 AIP Publishing LLC.

Aldrin J.C.,Computational Tools Inc. | Knopp J.S.,Air Force Research Lab | Blodgett M.P.,Air Force Research Lab
Studies in Applied Electromagnetics and Mechanics | Year: 2010

To improve the ability of eddy current nondestructive evaluation to characterize fatigue cracks in multilayer structures, a model-based image processing approach is presented that fits models based on first-principles to image data. Model refinements are presented that address edge responses, error associated with adjacent holes and poor hole centering due to cracks. Using this approach, improvements are demonstrated in the visual presentation of image data for crack detection and the potential for characterization. © 2010 The authors and IOS Press. All rights reserved.

Aldrin J.C.,Computational Tools Inc. | Annis C.,Statistical Engineering | Sabbagh H.A.,Victor Technologies, LLC | Knopp J.S.,Air Force Research Lab | Lindgren E.A.,Air Force Research Lab
AIP Conference Proceedings | Year: 2014

A comprehensive approach to NDE characterization error evaluation is presented that follows the framework of the 'ahat-versus-a' model evaluation process for probability of detection (POD) assessment. Before characterization error model building is performed, an intermediate step must evaluate the presence and frequency of several possible classes of poor characterization results. A case study is introduced based on the estimation the length, depth and width of surface breaking cracks using bolt hole eddy current (BHEC) NDE. This study highlights the importance of engineering and statistical expertise in the model-building process to ensure all key effects and possible interactions are addressed. © 2014 AIP Publishing LLC.

Aldrin J.C.,Computational Tools Inc. | Medina E.A.,SAIC | Lindgren E.A.,Air Force Research Lab | Buynak C.F.,Air Force Research Lab | Knopp J.S.,Air Force Research Lab
AIP Conference Proceedings | Year: 2012

This paper presents the results of a demonstration featuring the application of a validation protocol to a vibration-based structural damage sensing system. The results of the full validation study highlight the general protocol feasibility, emphasize the importance of evaluating key application characteristics prior to the POD study, and demonstrate an approach to quantify varying sensor durability on the POD performance. Challenges remain to properly address long time-scale effects with accelerated testing and large testing requirements due to the independence of the inspection of each flaw location. © 2012 American Institute of Physics.

Knopp J.S.,Air Force Research Lab | Grandhi R.,Wright State University | Aldrin J.C.,Computational Tools Inc. | Park I.,Wright State University
Journal of Nondestructive Evaluation | Year: 2013

Recent work on reliably detecting and characterizing cracks in multi-layer airframe structures has used modeling and simulation to extract features from raw eddy current data, and to assist in the evaluation of probability of detection (POD). This paper focuses on the statistical analysis of the data from these studies. Hit/miss, linear, and physics-inspired methods are employed to evaluate POD. The Box-Cox transformation is used as a remedy for violations of the constant variance assumption. In addition, a bootstrapping method is introduced for confidence bound calculation on a 2nd order linear model. The objective of this work is to provide on insight how different models and assumptions impact POD evaluation. © 2012 Springer Science+Business Media, LLC.

Aldrin J.C.,Computational Tools Inc. | Blodgett M.P.,Air Force Research Lab | Lindgren E.A.,Air Force Research Lab | Steffes G.J.,Air Force Research Lab | Knopp J.S.,Air Force Research Lab
Journal of the Acoustical Society of America | Year: 2011

Prior work has proposed the use of ultrasonic angle-beam shear wave techniques to detect cracks of varying angular location around fastener sites by generating and detecting creeping waves. To better understand the nature of the scattering problem and quantify the role of creeping waves in fastener site inspections, a 3D analytical model was developed for the propagation and scattering of an obliquely incident plane shear wave from a cylindrical cavity with arbitrary shear wave polarization. The generation and decay of the spiral creeping waves was found to be dependent on both the angle of incidence and polarization of the plane shear wave. A difference between the angle of displacement in 3D and the direction of propagation for the spiral creeping wave was observed and attributed to differences in the curvature of the cavity surface for the tangential and vertical (z) directions. Using the model, practical insight was presented on measuring the displacement response in the far-field from the hole. Both analytical and experimental results highlighted the value of the diffracted and leaky spiral creeping wave signals for nondestructive evaluation of a crack located on the cavity. Last, array and signal processing methods are discussed to improve the resolution of the weaker creeping wave signals in the presence of noise. © 2011 Acoustical Society of America.

Mooers R.D.,University of Dayton | Knopp J.S.,U.S. Air force | Aldrin J.C.,Computational Tools Inc. | Sathish S.,University of Dayton
AIP Conference Proceedings | Year: 2014

Eddy current measurements are sensitive to variation in the dimensions of probe. This paper presents the results of a parametric study conducted via simulation to determine the effects of varying dimensions on the split D differential eddy current probe response. Details about the study design, the numerical model and major results are presented. The results provide practical guidance on the sensitivity of certain probe dimensions on eddy current probe response. © 2014 AIP Publishing LLC.

Mooers R.D.,University of Dayton | Knopp J.S.,U.S. Air force | Aldrin J.C.,Computational Tools Inc. | Sathish S.,University of Dayton
AIP Conference Proceedings | Year: 2014

Benchmark and validation studies are presented that quantify the accuracy of computational models. An important factor in these studies is the ability to compare simulated impedance results with experimental data. In a majority of differential benchmark studies the data acquisition is handled by a commercial eddy current instrument which allow for only a relative comparison of the data. In this study a novel data acquisition system allows for the collection of impedance data for differential probes. Details about the data collection, experimental procedure, model construction, and data comparison will be presented. © 2014 AIP Publishing LLC.

Forsyth D.S.,TRI Austin | Aldrin J.C.,Computational Tools Inc. | Welter J.T.,U.S. Air force
International SAMPE Technical Conference | Year: 2013

Automated inspection systems are routinely deployed in manufacturing processes. Total inspection coverage is often required for flight safety-critical components. A long history of nondestructive testing (NDT) of metal components has given the industry confidence in these inspection systems. There is less corresponding history and confidence for fiber-reinforced polymer composites in primary structures, and the inspection burden is more significant. There are potentially multiple defect criteria, and the criteria will vary from part to part. The result is that highly trained, experienced, and relatively expensive NDT personnel are needed to review the enormous amounts of data collected by automated inspection systems. In this presentation, we describe an ongoing effort to automate the interpretation of ultrasonic inspection of composite structures. We consider defect types and acceptance criteria, design of Automated Defect Analysis (ADA) algorithms, validation, and the estimation of the return on investment obtained by implementing an on-line ADA software into the ultrasonic inspection system. Copyright 2013 by Aurora Flight Sciences.

Annis C.,Statistical Engineering | Aldrin J.C.,Computational Tools Inc. | Sabbagh H.A.,Victor Technologies, LLC
Materials Evaluation | Year: 2015

The statistical techniques in MIL-HDBK-1823A work for the large majority of situations, but not all situations. When the model (any mathematical model, not just a probability of detection [POD] model) does not have the same characteristics as the data, then it is the wrong model. Two, not uncommon, examples are a POD minimum value that never approaches zero, perhaps due to background noise, or a maximum POD that does not approach one, possibly a result of an occluded inspection site, while the MIL-HDBK-1823A requires asymptotes at both zero and one. The authors discuss a statistical procedure for adding an asymptote to the standard POD model, estimating its most likely value, and computing confidence bounds on that estimate. © 2015, American Society for Nondestructive Testing. All rights reserved.

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