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TL;DR: In this paper, a second-order approximation of the displacement gradients is proposed to directly measure both the first-and secondorder displacement gradient resulting from nonlinear deformation, which can be used to obtain more accurate strain measurements in large deformation situations.
Abstract: This paper outlines the procedure for refining the digital image correlation (DIC) method by implementing a second-order approximation of the displacement gradients. The second-order approximation allows the DIC method to directly measure both the first- and second-order displacement gradients resulting from nonlinear deformation. Thirteen unknown parameters, consisting of the components of displacement, the first- and second-order displacement gradients and the gray-scale value offset, are determined through optimization of a correlation coefficient. The previous DIC method assumes that the local deformation in a subset of pixels is represented by a first-order Taylor series approximation for the displacement gradient terms, so actual deformations consisting of higher order displacement gradients tend to distort the infinitesimal strain measurements. By refining the method to measure both the first- and second-order displacement gradients, more accurate strain measurements can be achieved in large-deformation situations where second-order deformations are also present. In most cases, the new refinements allow the DIC method to maintain an accuracy of ±0.0002 for the first-order displacement gradients and to reach ±0.0002 per pixel for the second-order displacement gradients.
370 citations
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TL;DR: In this article, a phenomenological constitutive model for shape memory alloys is presented, which is based on a scalar and a tensorial internal variable, with the property of completely decoupling the pure reorientation mechanism from the pure transformation mechanism.
233 citations
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TL;DR: Considering the risk-benefit relation, it would appear to be clear that hyperventilation should only be considered in patients with raised ICP, in a tailored way and under specific monitoring.
201 citations
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07 Jan 2013TL;DR: Results from the 5, AIAA CFD Drag Prediction Workshop are presented, focused on force/moment predictions for the NASA Common research wing-body configuration, including a grid refinement study and an optional buffet study.
Abstract: Results from the Fifth AIAA CFD Drag Prediction Workshop (DPW-V) are presented. As with past workshops, numerical calculations are performed using industry-relevant geometry, methodology, and test cases. This workshop focused on force/moment predictions for the NASA Common Research Model wing-body configuration, including a grid refinement study and an optional buffet study. The grid refinement study used a common grid sequence derived from a multiblock topology structured grid. Six levels of refinement were created resulting in grids ranging from 0.64x10(exp 6) to 138x10(exp 6) hexahedra - a much larger range than is typically seen. The grids were then transformed into structured overset and hexahedral, prismatic, tetrahedral, and hybrid unstructured formats all using the same basic cloud of points. This unique collection of grids was designed to isolate the effects of grid type and solution algorithm by using identical point distributions. This study showed reduced scatter and standard deviation from previous workshops. The second test case studied buffet onset at M=0.85 using the Medium grid (5.1x106 nodes) from the above described sequence. The prescribed alpha sweep used finely spaced intervals through the zone where wing separation was expected to begin. Some solutions exhibited a large side of body separation bubble that was not observed in the wind tunnel results. An optional third case used three sets of geometry, grids, and conditions from the Turbulence Model Resource website prepared by the Turbulence Model Benchmarking Working Group. These simple cases were intended to help identify potential differences in turbulence model implementation. Although a few outliers and issues affecting consistency were identified, the majority of participants produced consistent results.
122 citations
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TL;DR: It is shown that mixed collocation schemes are locking-free independently of the choice of the polynomial degrees for the unknown fields, and an important property is also analytically proven.
120 citations
Authors
Showing all 250 results
Name | H-index | Papers | Citations |
---|---|---|---|
Franco Brezzi | 68 | 197 | 29296 |
Ferdinando Auricchio | 63 | 502 | 14813 |
Luca Ansaloni | 61 | 418 | 12096 |
Jean-Michel Senard | 48 | 247 | 7452 |
Alessandro Reali | 44 | 207 | 9298 |
Gianmarco Manzini | 34 | 150 | 4237 |
Carlo Lovadina | 32 | 90 | 3099 |
Tarun Goswami | 28 | 89 | 2802 |
Hélène Hanaire | 27 | 98 | 2256 |
Vitor Engrácia Valenti | 26 | 358 | 3026 |
Heraldo Lorena Guida | 15 | 55 | 563 |
Haider N. Arafat | 12 | 31 | 670 |
Roberta Gonçalves da Silva | 11 | 62 | 616 |
David W. Levy | 10 | 16 | 880 |
Ana Cláudia Figueiredo Frizzo | 10 | 59 | 311 |