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Robert J. Grandin
Iowa State University
Finite element methodUltrasonic testingMaterials scienceComputer scienceStatistical power
21Publications
3H-index
21Citations
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Publications 21
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#1Onur Rauf Bingol (Iowa State University)H-Index: 2
#2Bryan Schiefelbein (Iowa State University)H-Index: 2
Last. Adarsh Krishnamurthy (Iowa State University)H-Index: 13
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Abstract Laminated fiber-reinforced polymer (FRP) composites are widely used in aerospace and automotive industries due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. Non-destructive evaluation (NDE) of composites using ultrasonic testing (UT) can identify the presence of defects. However, manually incorporating the damage in a CAD mod...
2 CitationsSource
#1Stephen D. HollandH-Index: 15
Last. Robert J. GrandinH-Index: 3
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Finite element models of composite structures are generally shell-based and modeled at the laminate level. More detailed layer-by-layer lamina-level models are sometimes needed for representing joints or for modeling defect growth processes. We describe a method and toolkit for automating the creation and insertion of layerby- layer finite element sub-models of composite laminate. We focus in particular on representing damage captured from nondestructive evaluation (NDE) measurements. The method...
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#1Robert J. GrandinH-Index: 3
#2Gavin YoungH-Index: 2
Last. Adarsh KrishnamurthyH-Index: 13
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Interactive x-ray simulations of complex computer-aided design (CAD) models can provide valuable insights for better interpretation of the defect signatures such as porosity from x-ray CT images. Generating the depth map along a particular direction for the given CAD geometry is the most compute-intensive step in x-ray simulations. We have developed a GPU-accelerated method for real-time generation of depth maps of complex CAD geometries. We preprocess complex components designed using commercia...
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#1Rafael RadkowskiH-Index: 11
#2Stephen D. HollandH-Index: 15
Last. Robert J. GrandinH-Index: 3
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#1Xiaosong DuH-Index: 3
#2Leifur LeifssonH-Index: 18
Last. Jiming SongH-Index: 4
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1 CitationsSource
#2Ronald A. RobertsH-Index: 9
Last. Robert J. GrandinH-Index: 3
view all 3 authors...
Source
#1Stephen D. HollandH-Index: 15
Last. Robert J. GrandinH-Index: 3
view all 4 authors...
Composite laminate structures are usually modeled as a shell in finite element analysis tools for strength and stiffness determination. However, modeling for fatigue or degradation analysis often needs to be performed with layer-by-layer solid models, but building these models for nontrivial geometries can be extremely difficult, especially when trying to represent realistic defects. This paper discusses how the process of generating layer-by-layer solid finite element models, including insertio...
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#1Robert J. GrandinH-Index: 3
Last. Ronald A. RobertsH-Index: 9
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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...
Source
#1Onur Rauf BingolH-Index: 2
#2Bryan SchiefelbeinH-Index: 2
Last. Adarsh KrishnamurthyH-Index: 13
view all 5 authors...
Fiber-reinforced composites are widely used in aerospace industry due to their combined properties of high strength and low weight. However, owing to their complex structure, it is difficult to assess the impact of manufacturing defects and service damage on their residual life. While, ultrasonic testing (UT) is the preferred NDE method to identify the presence of defects in composites, there are no reasonable ways to model the damage and evaluate the structural integrity of composites. We have ...
1 CitationsSource
#2Ronald A. RobertsH-Index: 9
Last. Robert J. GrandinH-Index: 3
view all 3 authors...
This paper reports on a computational study of ultrasound propagation in heterogeneous metal microstructures. Random spatial fluctuations in elastic properties over a range of length scales relative to ultrasound wavelength can give rise to scatter-induced attenuation, backscatter noise, and phase front aberration. It is of interest to quantify the dependence of these phenomena on the microstructure parameters, for the purpose of quantifying deleterious consequences on flaw detectability, and fo...
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