Session: 07-14-01 Measurement and Analysis Techniques in Nonlinear Dynamic Systems I

Paper Number: 67448

Start Time: Tuesday, 03:30 PM

67448 - Nonlinear Dynamics Investigation of Bending Deflection Of Stiffened Composite Laminated Plate Using Lyapunov Exponent Conception 

In this paper, the nonlinear dynamics behavior of bending deflection of stiffened composite laminated plate is investigated based on largest Lyapunov exponent parameter. Wolf algorithm is used to quantify largest Lyapunov exponent in the presence of aspect ratio and fiber volume fraction. When the value of largest Lyapunov exponent is negative which means that the motion of the stiffened plate is periodic while the value of largest Lyapunov exponent is positive which means that the motion stiffened plate could be either non-periodic and chaos. The application of this work can be found in vessels with varying suction pressure, longitudinal tubes in steam boilers, bodies of ships, and submarines space crafts. A power spectrum analysis has been added using the amplitude of Fast Fourier Transform (FFT) to detect the non-periodic motion of the stiffened composite laminated plate. The first peak in power spectrum tool refers to fundamental frequency (F). The amplitude of fundamental frequency and the other frequencies' peaks indicate to periodic motion of the stiffened composite laminated plate. When the frequencies' peaks have been started disappearing from (FFT) diagram, the motion of the stiffened plate converts to non-periodic motion and chaos. The algorithm of nonlinear dynamics tool is used to extract time delay and embedding dimensions. The algorithm of average mutual information (AMI) and global false nearest neighbors (GFNN) are used to determine the time delay and the embedding dimensions respectively. The first minimum intersection point downward from (AMI) curve represents the time delay. When the global false nearest curve of the neighbors attractor (GFNN) reaches zero along way with the embedding dimensions which gives the value of embedding dimensions. The analytic solution has been done using Higher Order Shear Deformation Theory (HOST). Numerical simulation is carried out using ANSYS software. The combined loading are the in-plane compression (uniaxial and biaxial) mechanical load and shear force. The experiment setup has been done using buckling test machine whereas the upper head is moved downwards by servo hydraulic cylinder. The value of critical buckling load is checked and verified at different thickness ratio, number of stiffeners, lamination angles, stiffener depth ratio based on different boundary conditions. All the values of largest Lyapunov exponent are positive which gives indication to non-periodic motion. The nonlinear dynamics behavior of stiffened composite laminated plate is decreased with the increasing of number of stiffeners in which the value of largest Lyapunov exponent has been decreased. The nonlinear dynamics behavior is increased with the increasing of aspect ratio and fiber volume fraction.

 

 

 

 
 

Presenting Author: Louay S. Yousuf San Diego State University

Authors:

Louay S. Yousuf San Diego State University