Elisabetta Manconi

Bio: Elisabetta Manconi is an academic researcher from University of Parma. The author has contributed to research in topics: Finite element method & Wave propagation. The author has an hindex of 7, co-authored 23 publications receiving 475 citations.

Wave motion and dispersion phenomena: Veering, locking and strong coupling effects

Abstract: The dispersion curves describe wave propagation in a structure, each branch representing a wave mode. As frequency varies the wavenumbers change and a number of dispersion phenomena may occur. This paper characterizes, analyzes, and quantifies these phenomena in general terms and illustrates them with examples. Two classes of phenomena occur. Weak coupling phenomena—veering and locking—arise when branches of the dispersion curves interact. These occur in the vicinity of the frequency at which, for undamped waveguides, the dispersion curves in the uncoupled waveguides would cross: if two dispersion curves (representing either propagating or evanescent waves) come close together as frequency increases then the curves either veer apart or lock together, forming a pair of attenuating oscillatory waves, which may later unlock into a pair of either propagating or evanescent waves. Which phenomenon occurs depends on the product of the gradients of the dispersion curves. The wave mode shapes which describe the deformation of the structure under the passage of a wave change rapidly around this critical frequency. These phenomena also occur in damped systems unless the levels of damping of the uncoupled waveguides are sufficiently different. Other phenomena can be attributed to strong coupling effects, where arbitrarily light stiffness or gyroscopic coupling changes the qualitative nature of the dispersion curves.

Numerical and experimental investigation of stop-bands in finite and infinite periodic one-dimensional structures

Abstract: Adding periodicity to structures leads to wavemode interaction, which generates pass- and stop-bands. The frequencies at which stop-bands occur are related to the periodic nature of the structure. ...

Modelling wave propagation in two-dimensional structures using a wave/finite element technique

Abstract: The purpose of this work is to present a general method for the numerical analysis of wave propagation in 2-dimensional structures by the use of a finite element method (FEM). The method involves typically just one finite element to which periodicity conditions are applied instead of modelling the whole structure, thus reducing drastically the cost of calculations. The mass and stiffness matrices are found using conventional FE software. The low order dynamic stiffness matrix so obtained is post-processed and the wavenumbers and the frequencies then follow from various resulting eigenproblems. The method is described and numerical examples given. These include isotropic and orthotropic plates, isotropic cylindrical shells and the more complex case of sandwich cylindrical shells for which analytical solutions are not available. The last two cases are studied by postprocessing an ANSYS FE model. The main advantage of the technique is its flexibility since standard FE routines can be used and therefore a wide range of structural configurations can be easily analysed. Moreover the propagation constants for plane harmonic waves can be easily predicted for different propagation directions along the structure. The method is seen to give accurate predictions at negligible computational cost