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Ronald A. Roberts
Iowa State University
103Publications
10H-index
421Citations
Publications 100
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#1Xiaosong Du (Iowa State University)H-Index: 3
#2Leifur Leifsson (Iowa State University)H-Index: 15
Last.Ronald A. Roberts (Iowa State University)H-Index: 10
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1 CitationsSource
#1Xiaosong Du (Iowa State University)H-Index: 3
#2Praveen Gurrala (Iowa State University)H-Index: 2
Last.Yonatan A. Tesfahunegn (RU: Reykjavík University)H-Index: 7
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Probability of detection (POD) is used for reliability analysis in nondestructive testing (NDT) area. Traditionally, it is determined by experimental tests, while it can be enhanced by physics-based simulation models, which is called model-assisted probability of detection (MAPOD). However, accurate physics-based models are usually expensive in time. In this paper, we implement a type of stochastic polynomial chaos expansions (PCE), as alternative of actual physics-based model for the MAPOD calc...
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#1Praveen GurralaH-Index: 2
#2Andrew DownsH-Index: 1
Last.Ronald A. RobertsH-Index: 10
view all 5 authors...
1 CitationsSource
#1Xiaosong DuH-Index: 3
#2Leifur LeifssonH-Index: 8
Last.Jiming SongH-Index: 7
view all 6 authors...
1 CitationsSource
#1Chien-Ping ChiouH-Index: 6
#2Frank J. MargetanH-Index: 16
Last.Ronald A. RobertsH-Index: 10
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#2Ronald A. RobertsH-Index: 10
Last.Robert J. GrandinH-Index: 3
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#1Praveen GurralaH-Index: 2
#2Kun ChenH-Index: 3
Last.Ronald A. RobertsH-Index: 10
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In this paper, we simulate some of the benchmark problems proposed by the World Federation of Nondestructive Evaluation Centers (WFNDEC) using a full wave simulation model based on accurate solutions to the boundary integral equations for ultrasonic scattering. Much of the previous work on modeling these problems relied on the Kirch-hoff approximation to find the scattered fields from defects. Here we instead use a numerical method, called the Nystrom method, for finding the scattered fields mor...
4 CitationsSource
#2Ronald A. RobertsH-Index: 10
Last.Leonard J. BondH-Index: 5
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Additive manufacturing provides a unique opportunity to embed defects of known size and shape to produce reference samples for inspection and quality control purposes. This paper reports defect detectability studies with cylindrical additively manufactured cobalt-chromium alloy specimens which contain defects of known sizes and distributions. The specimens were characterized using immersion, synthetic aperture focusing (SAFT), phased array, and nonlinear ultrasonic techniques. Results include de...
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#1Chien-Ping ChiouH-Index: 6
#2Frank J. MargetanH-Index: 16
Last.Daniel J. BarnardH-Index: 11
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Under the sponsorship of the National Science Foundation’s Industry/University Cooperative Research Center at Iowa State University, an effort was initiated in 2015 to repackage existing research-grade software into user friendly tools for the rapid estimation of signal-to-noise ratio (S/N) for ultrasonic inspections of metals. The software combines: (1) a Python-based graphical user interface for specifying an inspection scenario and displaying results; and (2) a Fortran-based engine for comput...
2 CitationsSource
#1Robert J. GrandinH-Index: 3
Last.Ronald A. RobertsH-Index: 10
view all 3 authors...
Due to the geometrical complexities of bolted, layered airframe structures, the application of Model Assisted Probability of Detection, or MAPOD, is an important tool for helping to assess the ultrasonic inspectability of those components. Of particular importance is the need to inspect for cracks on or near boltholes in those structures. This presentation describes the development and testing of analytical computer models of and their application to bolthole crack inspection. The modeling appro...
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