LOCAL WAVENUMBER EXTRACTION IN AN HONEYCOMB SANDWICH STRUCTURE

Abstract

Understanding the guided wave (GW) propagation/travelling mechanism in honeycomb composite panels with multiple frequencies is intrinsically difficult because to the complicated nature of HSS composite systems. To examine the wave propagation behavior in honeycomb sandwich constructions and constant thickness metallic plates employing piezoelectric actuators/sensors, a numerical simulation is first performed in this thesis work. The author describes a method for analyzing propagating multimode signals. A two dimensional Fourier Transform (FT) of the time history of the waves received at a sequence of evenly spaced places along the propagation/travel path is used in this method. The technique was used to gauge the amplitudes/intensity and velocities of Lamb waves travelling in a plate, with the output of the transform given as a three-dimensional picture of the wave-number dispersion curves using an isometric projection. The results of numerical and literary research to determine the wave-number and displacement data of Lamb waves propagating in steel plates and HSS of constant thickness (10mm) are provided. The results match well with analytical predictions, demonstrating the utility of the two-dimensional Fourier Transform (FT) (2-D). Elastic wave responses on the basis of true geometry of the honey-comb core are determined with the use of finite elements analysis (FEA) based software ABAQUS, in contrast to most earlier work. The global guided wave (GW)s in the composite can be seen when the loading frequency is low, and the leaky guided wave (GW)s in the skin panel can be seen when the loading frequency is sufficiently high, according to the simulation. The homogenisation technique's suitability for a celled core is examined. Wave propagation is also shown to be influenced by cell geometry. Finally, previous research work is analysed to validate the numerical simulation results, and there is a lot of agreement. With the existence of a honeycomb core, several guided wave (GW) propagation properties such as wave-number fluctuation with thickness and position, group velocity dispersion, and mode tuning possibilities are examined. In addition, the methodology utilized to achieve the intended results has been extensively explored, with careful attention paid to references and examples.