Sensitivity of co-prime arrays to shape perturbation

2013 ◽  
Author(s):  
Andrew Pyzdek ◽  
R. Lee Culver
Keyword(s):  
Shape Perturbation

Optimal design of aerospace structures using recent meta-heuristic algorithms

2021 ◽  
Vol 63 (11) ◽  
pp. 1025-1031
Author(s):  
Faik Fatih Korkmaz ◽  
Mert Subran ◽  
Ali Rıza Yıldız
Keyword(s):  
Heuristic Algorithms ◽  
Optimal Solution ◽  
Von Mises Stress ◽  
Grey Wolf Optimizer ◽  
Local Optima ◽  
Design And Optimization ◽  
Shape Perturbation ◽  
Novel Algorithms ◽  
Von Mises ◽  
Conventional Optimization

Abstract Most conventional optimization approaches are deterministic and based on the derivative information of a problem’s function. On the other hand, nature-inspired and evolution-based algorithms have a stochastic method for finding the optimal solution. They have become a more popular design and optimization tool, with a continually growing development of novel algorithms and new applications. Flexibility, easy implementation, and the capability to avoid local optima are significant advantages of these algorithms. In this study, shapes, and shape perturbation limits of a bracket part, which is used in aviation, have been set using the hypermorph tool. The objective function of the optimization problem is minimizing the volume, and the constraint is maximum von Mises stress on the structure. The grey wolf optimizer (GWO) and the moth-flame Optimizer (MFO) have been selected as nature-inspired evolution-based optimizers.

Instability caused by the coupling between non-resonant shape oscillation modes of a charged conducting drop

1997 ◽  
Vol 333 ◽  
pp. 1-21 ◽  
Author(s):  
Z. C. FENG
Keyword(s):  
Liquid Drop ◽  
Multiple Scale ◽  
High Mode ◽  
Mode Number ◽  
Nonlinear Coupling ◽  
Modal Interaction ◽  
Amplitude Equations ◽  
Oscillation Modes ◽  
Shape Oscillation ◽  
Shape Perturbation

By examining the modal interaction between two non-resonant shape oscillation modes of a charged liquid drop, we have identified a new route to instability via nonlinear coupling. We present numerical simulation results to show that when shape perturbation of a high-mode number Legendre mode is applied to the drop, the prolate–oblate mode of the drop may grow unbounded. Using multiple-scale analysis, we derive amplitude equations for the high-mode-number shape mode and the prolate–oblate mode to show the nonlinear coupling between the two modes.

Interfacial Dynamics of Water-in-Oil Dropliets: a Temperature-Jump Investigation

1992 ◽  
Vol 290 ◽  
Author(s):  
Paschalis Alexandridis ◽  
Josef F. Holzwarth ◽  
T. Alan Hatton
Keyword(s):  
Initial Temperature ◽  
Temperature Jump ◽  
Salt Content ◽  
Time Interval ◽  
Bending Rigidity ◽  
Bending Modulus ◽  
System Equilibrium ◽  
Shape Perturbation ◽  
Laser Temperature Jump ◽  
Spherical Interface

AbstractThe dynamic response of water-in-oil AOT microemulsion droplets to perturbations caused by rapid energy transfer has been interpreted in terms of the surfactant interface bending rigidity. The Iodine Laser Temperature Jump technique was used to rapidly (1 μs) increase the microemulsion temperature and thus disturb the system equilibrium. The dynamic relaxation to the new equilibrium position was monitored by measuring the turbidity of the microemulsion over a I ms time interval immediately after the temperature jump. The rate and direction of the turbidity change depended on the initial temperature, size and salt content of the water droplets. We observed characteristic times of 2 to 10 μs and attributed them to the relaxation of the surfactant interface. A bending modulus of 0.4 kT was derived for the AOT interface, using a model for the shape perturbation of a spherical interface.

Prediction of Turbomachinery Aeroelastic Behavior From a Set of Representative Modes

2011 ◽  
Author(s):  
Mari´a A. Mayorca ◽  
Damian M. Vogt ◽  
Hans Ma˚rtensson ◽  
Torsten H. Fransson
Keyword(s):  
Wide Frequency Range ◽  
Least Square ◽  
Mode Shapes ◽  
Frequency Range ◽  
Reduced Order ◽  
Transonic Compressor ◽  
Unsteady Aerodynamic ◽  
Shape Perturbation ◽  
Selection Of

A method is proposed for the determination of the aeroelastic behavior of a system responding to mode-shapes different to the tuned in-vacuo ones, due to mistuning, mode family interaction or any other source of mode-shape perturbation. The method is based on the generation of a data base of unsteady aerodynamic forces arising from the motion of arbitrary modes and uses Least Square approximations for the prediction of any responding mode. The use of a reduced order technique allows for mistuning analyses and is also applied for the selection of a limited number of arbitrary modes. The application on a transonic compressor blade shows that the method captures well the aeroelastic properties in a wide frequency range. A discussion of the influence of the mode-shapes and frequency on the final stability response is also provided.

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