William Winfree - Academia.edu (original) (raw)
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Papers by William Winfree
Frontiers in Mechanical Engineering, Apr 9, 2021
Simple methods for reducing the pulsed thermographic responses of flaws have tended to be based o... more Simple methods for reducing the pulsed thermographic responses of flaws have tended to be based on either the spatial or temporal response. This independent assessment limits the accuracy of characterization. A variational approach is presented for reducing the thermographic data to produce an estimated size for a flaw that incorporates both the temporal and spatial response to improve the characterization. The size and depth are determined from both the temporal and spatial thermal response of the exterior surface above a flaw and constraints on the length of the contour surrounding the delamination. Examples of the application of the technique to simulation and experimental data acquired are presented to investigate the limitations of the technique.
American Society of Composites - 30th Technical Conference, Sep 28, 2015
A study of nondestructive evaluation of aircraft bonded joints using the contact scanning techniq... more A study of nondestructive evaluation of aircraft bonded joints using the contact scanning technique is presented. Reflected signals acquired through the contacting transducer characterize the test region as being bonded or disbonded. Ultrasonic signals are attenuated more rapidly in the bonded regions when compared to disbonded regions. A peak amplitude based method and an artificial neural network are used to classify the signals. Results obtained using an artificial neural network exhibited significant insensitivity to signal variation when compared to the peak amplitude. Very good agreement is observed between results obtained using the present technique and those obtained using immersion scanning.
Passive thermography has been shown to be an effective method for in situ and real time nondestru... more Passive thermography has been shown to be an effective method for in situ and real time nondestructive evaluation (NDE) to measure damage growth in a composite structure during cyclic loading. The heat generation by subsurface flaws results in a measurable thermal profile at the surface. To better understand these sources, the quadrupole method is used to simulate the resultant temperature profile for a subsurface heat source. The simulations are compared to finite difference and finite element simulations of the same sources and experimental data acquired during cyclic loading of a composite specimen.
Frontiers in Mechanical Engineering, Apr 9, 2021
Simple methods for reducing the pulsed thermographic responses of flaws have tended to be based o... more Simple methods for reducing the pulsed thermographic responses of flaws have tended to be based on either the spatial or temporal response. This independent assessment limits the accuracy of characterization. A variational approach is presented for reducing the thermographic data to produce an estimated size for a flaw that incorporates both the temporal and spatial response to improve the characterization. The size and depth are determined from both the temporal and spatial thermal response of the exterior surface above a flaw and constraints on the length of the contour surrounding the delamination. Examples of the application of the technique to simulation and experimental data acquired are presented to investigate the limitations of the technique.
American Society of Composites - 30th Technical Conference, Sep 28, 2015
A study of nondestructive evaluation of aircraft bonded joints using the contact scanning techniq... more A study of nondestructive evaluation of aircraft bonded joints using the contact scanning technique is presented. Reflected signals acquired through the contacting transducer characterize the test region as being bonded or disbonded. Ultrasonic signals are attenuated more rapidly in the bonded regions when compared to disbonded regions. A peak amplitude based method and an artificial neural network are used to classify the signals. Results obtained using an artificial neural network exhibited significant insensitivity to signal variation when compared to the peak amplitude. Very good agreement is observed between results obtained using the present technique and those obtained using immersion scanning.
Passive thermography has been shown to be an effective method for in situ and real time nondestru... more Passive thermography has been shown to be an effective method for in situ and real time nondestructive evaluation (NDE) to measure damage growth in a composite structure during cyclic loading. The heat generation by subsurface flaws results in a measurable thermal profile at the surface. To better understand these sources, the quadrupole method is used to simulate the resultant temperature profile for a subsurface heat source. The simulations are compared to finite difference and finite element simulations of the same sources and experimental data acquired during cyclic loading of a composite specimen.