18 research outputs found
Inclusion of Geometrically Nonlinear Aeroelastic Effects into Gradient-Based Aircraft Optimization
While aircraft have largely featured flexible wings for decades, more
recently, aircraft structures have rapidly become more flexible. The pursuit of
longer ranges and higher efficiency through higher aspect ratio wings, as well
as the introduction of modern, light-weight materials has yielded moderately and
very flexible aircraft configurations. Past accidents, such as the loss of the
Helios High Altitude Long Endurance (HALE) aircraft have highlighted the
limitations of linear analysis methods and demonstrated the peril of neglecting
nonlinear effects when designing such aircraft. In particular, accounting for
geometrical nonlinearities in flutter analyses become necessary in aircraft
optimization, including transport aircraft, or future aircraft may require
costly modifications late in the design process to fulfill certification
requirements. As a result, there is a need to account for geometrical
nonlinearities earlier in the design process and integrate these analyses
directly into the multi-disciplinary design optimization (MDO) problems.
This thesis investigates geometrically nonlinear flutter problems and how these
should be integrated into aircraft MDO problems. First, flutter problems with
and without geometrical nonlinearities are discussed and a unifying
interpretation is presented. Furthermore, methods for interpreting nonlinear
flutter problems are proposed and differences between linear and nonlinear
flutter problem interpretation are discussed. Next, a flutter constraint
formulation which accounts for geometrically nonlinear effects using beam-based
analyses is presented. The resulting constraint uses a
Kreisselmeiser-Steinhauser aggregation function to yield a scalar constraint
from flight envelope flutter damping values. While the constraint enforces
feasibility over the entire flight envelope, how the flight envelope is sampled
largely determines the flutter constraint’s accuracy. To this end, a constrained
Maximin approach, which is applicable for non-hypercube spaces, is used to
sample the flight envelope and obtain a low-discrepancy sample set. The flutter
constraint is then implemented using a beam-based geometrically nonlinear
aeroelastic simulation code, UM/NAST.
As gradient-based optimization methods are used in MDO due to the large number
of design variables in aircraft design problems, the flutter constraint requires
the recovery of flutter damping sensitivities. These are obtained by applying
algorithmic differentiation (AD) to the UM/NAST code base. This enables the
recovery of gradients for any solution type (static, modal, dynamic, and
flutter/stability) with respect to any local design variable available within
UM/NAST. The performance of the gradient prediction is studied and a
hybrid primal-AD scheme is developed to obtain the coupled nonlinear aeroelastic
sensitivities. After verifying the accuracy and performance of the gradient
evaluation, the flutter constraint was implemented in a sample optimization
problem.
Finally, a roadmap for including the beam-based flutter constraint within an
aircraft design problem is presented using analyses of varying fidelity. To this
end, analyses of appropriate fidelity are used depending on the output of
interest. While a shell-based FEM model can recover stress distributions, and is
therefore well-suited for strength constraints, they are ill-suited for
geometrically nonlinear flutter constraints due to their computational cost.
Analyses are presented for a high aspect ratio transport aircraft configuration
to illustrate the proposed approach and highlight the necessity for the
inclusion of a geometrically nonlinear flutter constraint.PHDAerospace EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/163259/1/clupp_1.pd
THE CONCISE GUIDE TO PHARMACOLOGY 2019/20 : G protein- coupled receptors
The Concise Guide to PHARMACOLOGY 2019/20 is the fourth in this series of biennial publications. The Concise Guide provides concise overviews of the key properties of nearly 1800 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide represents approximately 400 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.14748. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2019, and supersedes data presented in the 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the International Union of Basic and Clinical Pharmacology Committee on Receptor Nomenclature and Drug Classification (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.Peer reviewe
THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: G protein-coupled receptors
The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15538. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate
THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: G protein-coupled receptors.
The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15538. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate
Aeroelastic Tailoring for Maximizing Sailplane Average Cross-Country Speed
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140514/1/6.2015-2242.pd
Modeling and Simulation of Flexible Jet Transport Aircraft with High-Aspect-Ratio Wings
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140603/1/6.2016-2046.pd