John C. Aldrin
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View article: Comparative Assessment of Two Numerical Methods for Eddy Current Nondestructive Evaluation: Insights from Benchmark Studies
Comparative Assessment of Two Numerical Methods for Eddy Current Nondestructive Evaluation: Insights from Benchmark Studies Open
View article: Azimuthally Scanned Angled-Beam Pulse-Echo Ultrasound for Characterization of Impact Damage in Composites
Azimuthally Scanned Angled-Beam Pulse-Echo Ultrasound for Characterization of Impact Damage in Composites Open
Characterization of barely visible impact damage (BVID) in polymer matrix composites (PMCs) is necessary to use slow crack growth damage tolerance models and evaluate remaining life of PMC components. Azimuthally scanned angled-beam pulse-…
View article: Demonstration of using signal feature extraction and deep learning neural networks with ultrasonic data for detecting challenging discontinuities in composite panels
Demonstration of using signal feature extraction and deep learning neural networks with ultrasonic data for detecting challenging discontinuities in composite panels Open
For the ultrasonic inspection of large composite structures, certain inspection scenarios can be difficult to interpret due to the superposition of reflected signals from the panel surface and the discontinuities in the material. In recent…
View article: Distinguishing cracks and non-metallic inclusions using eddy current nondestructive evaluation and model-based inversion
Distinguishing cracks and non-metallic inclusions using eddy current nondestructive evaluation and model-based inversion Open
Recent work has demonstrated the capability of applying inverse methods to automated eddy current (EC) data of surface breaking cracks and notches of various sizes, orientations and aspect ratios. However, not all eddy current indications …
View article: Ultrasound forward model validation of normal incidence longitudinal wave and angle beam shear wave inspection of a quasi-isotropic composite layup with embedded damage
Ultrasound forward model validation of normal incidence longitudinal wave and angle beam shear wave inspection of a quasi-isotropic composite layup with embedded damage Open
Nondestructive characterization is a critical input to lifecycle management of composite structures. Characterization may be achieved through model-based inversion of an ultrasound inspection; however, this approach requires a validated fo…
View article: Process compensated resonance testing (PCRT) inversion for material characterization and digital twin calibration
Process compensated resonance testing (PCRT) inversion for material characterization and digital twin calibration Open
The Digital Twin paradigm is based on the idea that a component's serviceable life and performance can be better predicted and monitored by creating a faithful virtual counterpart of a real component, which in turn leads to improvements in…
View article: Oblique angle pulse echo ultrasound for delamination characterization
Oblique angle pulse echo ultrasound for delamination characterization Open
Characterization of delamination fields in 3D for impact-damaged composites is necessary to achieve the USAF objective of damage tolerance for polymer matrix composites. Oblique angle pulse echo ultrasound inspection has been hypothesized …
View article: Investigations of pitch-catch angled-beam ultrasonic NDE for characterization of hidden regions of impact damage in composites
Investigations of pitch-catch angled-beam ultrasonic NDE for characterization of hidden regions of impact damage in composites Open
This study explores the use of angled-beam ultrasonic NDE for the potential characterization of hidden regions of impact damage in composites. While simulations of an angled-beam pulse-echo inspections have shown the potential to detect bo…
View article: The need and approach for characterization - U.S. air force perspectives on materials state awareness
The need and approach for characterization - U.S. air force perspectives on materials state awareness Open
This paper expands on the objective and motivation for NDE-based characterization and includes a discussion of the current approach using model-assisted inversion being pursued within the Air Force Research Laboratory (AFRL). This includes…
View article: Signal decomposition for surrogate modeling of a constrained ultrasonic design space
Signal decomposition for surrogate modeling of a constrained ultrasonic design space Open
The U.S. Air Force seeks to improve the methods and measures by which the lifecycle of composite structures are managed. Nondestructive evaluation of damage – particularly internal damage resulting from impact – represents a significant in…
View article: Part-to-itself model inversion in process compensated resonance testing
Part-to-itself model inversion in process compensated resonance testing Open
Process Compensated Resonance Testing (PCRT) is a non-destructive evaluation (NDE) method involving the collection and analysis of a part's resonance spectrum to characterize its material or damage state. Prior work used the finite element…
View article: B-scan technique for localization and characterization of fatigue cracks around fastener holes in multi-layered structures
B-scan technique for localization and characterization of fatigue cracks around fastener holes in multi-layered structures Open
The work presented here aims to develop and transition angled-beam shear-wave inspection techniques for crack localization at fastener sites in multi-layer aircraft structures. This requires moving beyond detection to achieve reliable crac…
View article: Ultrasonic assessment of additive manufactured Ti-6Al-4V
Ultrasonic assessment of additive manufactured Ti-6Al-4V Open
Additive Manufacturing (AM) processes offer the potential for manufacturing cost savings and rapid insertion into service through production of near net shape components for complicated structures. Use of these parts in high reliability ap…
View article: Gaussian process regression of chirplet decomposed ultrasonic B-scans of a simulated design case
Gaussian process regression of chirplet decomposed ultrasonic B-scans of a simulated design case Open
The US Air Force seeks to implement damage tolerant lifecycle management of composite structures. Nondestructive characterization of damage is a key input to this framework. One approach to characterization is model-based inversion of the …
View article: Optimization of an angle-beam ultrasonic approach for characterization of impact damage in composites
Optimization of an angle-beam ultrasonic approach for characterization of impact damage in composites Open
Advances in NDE method development are greatly improved through model-guided experimentation. In the case of ultrasonic inspections, models which provide insight into complex mode conversion processes and sound propagation paths are essent…
View article: Uncertainty quantification of resonant ultrasound spectroscopy for material property and single crystal orientation estimation on a complex part
Uncertainty quantification of resonant ultrasound spectroscopy for material property and single crystal orientation estimation on a complex part Open
A case study is presented evaluating uncertainty in Resonance Ultrasound Spectroscopy (RUS) inversion for a single crystal (SX) Ni-based superalloy Mar-M247 cylindrical dog-bone specimens. A number of surrogate models were developed with F…
View article: Model-driven optimization of oblique angle ultrasonic inspection parameters for delamination characterization
Model-driven optimization of oblique angle ultrasonic inspection parameters for delamination characterization Open
Characterization of delamination fields in 3D for impact damaged composites is necessary to achieve the USAF objective of damage tolerance for polymer matrix composites [1, 2]. In order to characterize the hidden region of delamination fie…
View article: Eddy current analysis of cracks grown from surface defects and non-metallic particles
Eddy current analysis of cracks grown from surface defects and non-metallic particles Open
Eddy current methods are sensitive to any discrete change in conductivity. Traditionally this has been used to determine the presence of a crack. However, other features that are not cracks such as non-metallic inclusions, carbide stringer…
View article: Fundamentals of angled-beam ultrasonic NDE for potential characterization of hidden regions of impact damage in composites
Fundamentals of angled-beam ultrasonic NDE for potential characterization of hidden regions of impact damage in composites Open
In this study, the use of angled-beam ultrasonic NDE was explored for the potential characterization of the hidden regions of impact damage in composites. Simulated studies using CIVA FIDEL 2D were used to explore this inspection problem. …
View article: Detection and quantification of creep strain using process compensated resonance testing (PCRT) sorting modules trained with modeled resonance spectra
Detection and quantification of creep strain using process compensated resonance testing (PCRT) sorting modules trained with modeled resonance spectra Open
Process Compensated Resonant Testing (PCRT) is a full-body nondestructive testing (NDT) method that measures the resonance frequencies of a part and correlates them to the part's material and/or damage state. PCRT testing is used in the au…
View article: Continued developments in the modeling of complex dimensions and orientation variation in split D differential eddy current probes
Continued developments in the modeling of complex dimensions and orientation variation in split D differential eddy current probes Open
In this paper, model benchmarking for differential eddy current probes is presented, addressing increasing probe complexity including asymmetry, positional, and orientation variations. In prior work, results were presented showing that cur…
View article: Volumetric characterization of delamination fields via angle longitudinal wave ultrasound
Volumetric characterization of delamination fields via angle longitudinal wave ultrasound Open
The volumetric characterization of delaminations necessarily precedes rigorous composite damage progression modeling. Yet, inspection of composite structures for subsurface damage remains largely focused on detection, resulting in a capabi…
View article: Process compensated resonance testing modeling for damage evolution and uncertainty quantification
Process compensated resonance testing modeling for damage evolution and uncertainty quantification Open
Process Compensated Resonance Testing (PCRT) is a nondestructive evaluation (NDE) method based on the fundamentals of Resonant Ultrasound Spectroscopy (RUS). PCRT is used for material characterization, defect detection, process control and…
View article: Localization and characterization of fatigue cracks around fastener holes using spherically focused ultrasonic probes
Localization and characterization of fatigue cracks around fastener holes using spherically focused ultrasonic probes Open
Results are presented from laboratory experiments and simulations that demonstrate the ability to localize fatigue cracks around fastener holes using spherically focused ultrasonic probes for shear-wave inspections. For the experiments, fa…
View article: Model-based probe state estimation and crack inverse methods addressing eddy current probe variability
Model-based probe state estimation and crack inverse methods addressing eddy current probe variability Open
A model-based calibration process is introduced that estimates the state of the eddy current probe. First, a carefully designed surrogate model was built using VIC-3D® simulations covering the critical range of probe rotation angles, tilt …
View article: Model benchmarking and reference signals for angled-beam shear wave ultrasonic nondestructive evaluation (NDE) inspections
Model benchmarking and reference signals for angled-beam shear wave ultrasonic nondestructive evaluation (NDE) inspections Open
For model benchmark studies, the accuracy of the model is typically evaluated based on the change in response relative to a selected reference signal. The use of a side drilled hole (SDH) in a plate was investigated as a reference signal f…
View article: Bayesian flaw characterization from eddy current measurements with grain noise
Bayesian flaw characterization from eddy current measurements with grain noise Open
The Bayesian approach to inference from measurement data has the potential to provide highly reliable characterizations of flaw geometry by quantifying the confidence in the estimate results. The accuracy of these confidence estimates depe…
View article: Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution
Flaw characterization using inversion of eddy current response and the effect of filters and scan resolution Open
The objective of this work is to expand eddy current inversion methods to enable estimation of flaw dimensions and orientations for data collected using a variety of scan resolutions and filter configurations. Prior work [1, 2] has demonst…
View article: Uncertainty quantification in modeling and measuring components with resonant ultrasound spectroscopy
Uncertainty quantification in modeling and measuring components with resonant ultrasound spectroscopy Open
Resonant Ultrasound Spectroscopy (RUS) is a nondestructive evaluation (NDE) method which can be used for material characterization, defect detection, process control and life monitoring for critical components in gas turbine engines, aircr…
View article: Effects of angular variation on split D differential eddy current probe response
Effects of angular variation on split D differential eddy current probe response Open
The complexity of the models used in validation studies over the last few years has increased. Complexity has been included in the probe operation, the core/coil shape, the inclusion of ferrite cores, and the inclusion of dimension and ori…