An improved transformation for universal serendipity elements

Utku, M
This paper describes the formulation of shape functions and their derivatives for universal serendipity elements in finite element analysis, which allows for flexibility in locating edge nodes. Universal serendipity elements are defined as isoparametric elements having linear, quadratic and cubic node configurations at their edges in an arbitrary manner. Edge nodes positioned at the same relative distance from corner nodes in both master element and physical element provide improved accuracy over nodes positioned locally without regard for the global configuration. The nea formulation allows the user to change the order of elements in a very simple manner and also provides accurate solutions for nodal positions, which are not allowed using the standard elements. (C) 1999 Civil-Comp Ltd and Elsevier Science Ltd. All rights reserved.


A new modal superposition method for nonlinear vibration analysis of structures using hybrid mode shapes
Ferhatoglu, Erhan; Ciğeroğlu, Ender; Özgüven, Hasan Nevzat (Elsevier BV, 2018-07-01)
In this paper, a new modal superposition method based on a hybrid mode shape concept is developed for the determination of steady state vibration response of nonlinear structures. The method is developed specifically for systems having nonlinearities where the stiffness of the system may take different limiting values. Stiffness variation of these nonlinear systems enables one to define different linear systems corresponding to each value of the limiting equivalent stiffness. Moreover, the response of the n...
Monte Carlo analysis of ridged waveguides with transformation media
Ozgun, Ozlem; Kuzuoğlu, Mustafa (Wiley, 2013-07-01)
A computational model is presented for Monte Carlo simulation of waveguides with ridges, by combining the principles of transformation electromagnetics and the finite methods (such as finite element or finite difference methods). The principle idea is to place a transformation medium around the ridge structure, so that a single and easy-to-generate mesh can be used for each realization of the Monte Carlo simulation. Hence, this approach leads to less computational resources. The technique is validated by me...
An improved method for inference of piecewise linear systems by detecting jumps using derivative estimation
Selcuk, A. M.; Öktem, Hüseyin Avni (Elsevier BV, 2009-08-01)
Inference of dynamical systems using piecewise linear models is a promising active research area. Most of the investigations in this field have been stimulated by the research in functional genomics. In this article we study the inference problem in piecewise linear systems. We propose first identifying the state transitions by detecting the jumps of the derivative estimates, then finding the guard conditions of the state transitions (thresholds) from the values of the state variables at the state transitio...
A novel CEM technique for modeling electromagnetic scattering from metasurfaces
ÖZGÜN, ÖZLEM; Mittra, Raj; Kuzuoğlu, Mustafa (Wiley, 2020-03-01)
This paper presents a novel computational electromagnetics (CEM) technique, which hybridizes the periodic finite element method (FEM) with the method of moments (MoM), for efficient numerical modeling of electromagnetic scattering from metasurfaces consisting of truncated periodic or locally varying quasi-periodic array of structures. Based on the quasi-periodic nature of metasurfaces, the periodic FEM is employed to generate high-level macro basis functions (MBFs). Following that, a reduced MoM matrix is f...
A frequency domain nonparametric identification method for nonlinear structures: Describing surface method
Karaagacli, Taylan; Özgüven, Hasan Nevzat (Elsevier BV, 2020-10-01)
In this paper a new method called 'Describing Surface Method' (DSM) is developed for nonparametric identification of a localized nonlinearity in structural dynamics. The method makes use of the Nonlinearity Matrix concept developed in the past by using classical describing function theory, which assumes that nonlinearity depends mainly on the response amplitude and frequency dependence is negligible for almost all of the standard nonlinear elements. However, this may not always be the case for complex nonli...
Citation Formats
M. Utku, “An improved transformation for universal serendipity elements,” Budapest, HUNGARY, 1999, vol. 73, p. 199, Accessed: 00, 2020. [Online]. Available: