Calculation of 3D electromagnetic problems by combining the MFIE and the modal expansion technique

1990 ◽  
Author(s):  
N.Y. Zhu ◽  
F.M. Landstorfer
Keyword(s):  
Modal Expansion ◽  
Electromagnetic Problems ◽  
Expansion Technique

scholarly journals Partial Energy Transfer Model of Lamb Waves Scattering in Materially Isotropic Waveguides

2021 ◽  
Vol 11 (10) ◽  
pp. 4508
Author(s):  
Pavel Šofer ◽  
Michal Šofer ◽  
Marek Raček ◽  
Dawid Cekus ◽  
Paweł Kwiatoń
Keyword(s):  
Energy Transfer ◽  
Lamb Waves ◽  
Hybrid Approach ◽  
Wave Mode ◽  
Transfer Model ◽  
Material Interface ◽  
Modal Expansion ◽  
Scattering Coefficients ◽  
Expansion Technique ◽  
Partial Energy

The scattering phenomena of the fundamental antisymmetric Lamb wave mode with a horizontal notch enabling the partial energy transfer (PET) option is addressed in this paper. The PET functionality for a given waveguide is realized using the material interface. The energy scattering coefficients are identified using two methods, namely, a hybrid approach, which utilizes the finite element method (FEM) and the general orthogonality relation, and the semi-analytical approach, which combines the modal expansion technique with the orthogonal property of Lamb waves. Using the stress and displacement continuity conditions on the present (sub)waveguide interfaces, one can explicitly derive the global scattering matrix, which allows detailed analysis of the scattering process across the considered interfaces. Both methods are then adopted on a simple representation of a surface breaking crack in the form of a vertical notch, of which a certain section enables not only the reflection of the incident energy, but also its nonzero transfer. The presented results show very good conformity between both utilized approaches, thus leading to further development of an alternative technique.

scholarly journals Efficient Model Order Reduction of Structural Dynamic Systems with Local Nonlinearities under Periodic Motion

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
M. Mohammadali ◽  
H. Ahmadian
Keyword(s):  
Harmonic Balance Method ◽  
Order Reduction ◽  
Nonlinear Effects ◽  
Discrete Systems ◽  
Algebraic Equations ◽  
Structural Dynamic ◽  
Model Order ◽  
Modal Expansion ◽  
Expansion Technique ◽  
Nonlinear Algebraic Equations

In many nonlinear structural systems, compared with the local regions with induced nonlinear effects, the main portions of the structures are linear. An exact condensation technique based on the harmonic balance method (HBM) in conjunction with the modal expansion technique is employed to convert the motion equations of such a system to a set of nonlinear algebraic equations that are considerably small and adequately accurate to determine periodic responses. To demonstrate the capability of the suggested method, few case studies consisting of discrete systems with weak and essential nonlinearities are studied, and the results are compared to other methodologies results.

Mode Shape Expansion Techniques for Model Error Localization and Damage Detection

1995 ◽  
Author(s):  
Marie B. Levine-West ◽  
Mark H. Milman
Keyword(s):  
Mode Shape ◽  
Optimization Problems ◽  
Inequality Constraints ◽  
Model Error ◽  
Analytical Models ◽  
Mode Shapes ◽  
Orthogonal Projections ◽  
Modal Expansion ◽  
Expansion Technique ◽  
Quadratic Inequality Constraints

Abstract Several methods for mode shape expansion are investigated. The most popular methods use the dynamic equations of motions to obtain direct solutions, or use orthogonal projections. Both approaches can also be formulated as constrained optimization problems. To account for uncertainties in the measurements and in the prediction, a new expansion technique based on least squares minimization with quadratic inequality constraints (LSQI) is proposed. Each modal expansion technique is evaluated with experimental data obtained on the Micro-Precision Interferometer testbed, using both the pre-test and updated analytical models. The robustness of these methods is verified with respect to measurement noise and model error. It is shown that the proposed LSQI method has the best performance and can reliably predict mode shapes, and can be used to locate damage elements, even in very adverse situations. A new LSQI algorithm is also proposed which significantly decreases the solution time.

Full-Field Strain Monitoring of a Wind Turbine Using Very Limited Set of Displacements Measured With Three-Dimensional Point Tracking

2015 ◽  
Author(s):  
Javad Baqersad ◽  
Peyman Poozesh ◽  
Christopher Niezrecki ◽  
Peter Avitabile
Keyword(s):  
Wind Turbine ◽  
Three Dimensional ◽  
Element Model ◽  
Turbine Rotor ◽  
Field Strain ◽  
Full Field ◽  
Modal Expansion ◽  
Point Tracking ◽  
Expansion Technique ◽  
Measured Displacement

In the current work, the optical three-dimensional point-tracking (3DPT) measurement approach is used in conjunction with a recently developed modal expansion technique. These two approaches (empirical and analytical) complement each other and enable the prediction of the full-field dynamic response on the surface of the structure as well as within the interior points. The practical merit of the approach was verified using a non-spinning and spinning wind turbine rotor. The three-bladed wind turbine rotator was subjected to different loading scenarios and the displacement of optical targets located on the blades was measured using 3DPT. The measured displacement was expanded and applied to the finite element model of the turbine to extract full-field strain on the turbine. The sensitivity of the proposed approach to the number of optical targets was studied in this paper. It is shown the approach can accurately predict the strain even with very few set of measurement points.

A Quasi-Analytic Modal Expansion Technique for Modeling Light Emission From Nanorod LEDs

2014 ◽  
Vol 50 (9) ◽  
pp. 1-8 ◽  
Author(s):  
Simon E. J. O'Kane ◽  
J. Sarma ◽  
Duncan W. E. Allsopp
Keyword(s):  
Light Emission ◽  
Modal Expansion ◽  
Expansion Technique

Transient Response of Beams, Plates, and Shells to Impulsive Loads

2007 ◽  
Author(s):  
Serge Abrate
Keyword(s):  
Natural Frequencies ◽  
Vibration Mode ◽  
Analysis Method ◽  
The Finite Element Method ◽  
Fundamental Vibration ◽  
Short Pulses ◽  
Modal Expansion ◽  
Expansion Technique ◽  
Impulsive Loads ◽  
Plates And Shells

Beams, plates and shells are used in many applications where there can be subjected to short duration loads due to impacts or pressure blasts. Here the response of such distributed systems is examined using the modal expansion technique for pulse shapes typically observed during impacts and explosions. The objective is to gain an understanding of the behavior of these structures. For beams and plates the natural frequencies are generally well separated and, typically, a small number of modes participate in the response. Pulses can be classified as being either short, long, or intermediate in comparison with the period of the fundamental vibration mode. Very different behaviors are observed for the three types of pulses. For short pulses, the response depends on impulse applied not on the shape of the pulse and it can be accurately predicted by the response to an equivalent impulse. For long pulses, the maximum response depends on the magnitude of the load applied. For shells, the effect of curvature can be significant and result in several modes with close frequencies. In that case the response is more complicated since many modes participate in the response. In this work, the criteria are developed for predicting the response of each mode to a various pulses and determine how many modes participate in the response. The results obtained are applicable with any other analysis method including the finite element method.

scholarly journals Analysis of Circular Microstrip Patch Antenna Using Spherical Modal Expansion Technique

2011 ◽  
Vol 16 (5) ◽  
pp. 28-34
Author(s):  
Rukmini T S ◽  
Shilpa J ◽  
Ravishankar S ◽  
K S Shushrutha ◽  
S.K. Thakur
Keyword(s):  
Patch Antenna ◽  
Microstrip Patch Antenna ◽  
Modal Expansion ◽  
Microstrip Patch ◽  
Expansion Technique
Sign in / Sign up

Export Citation Format

Share Document