EFFECTS OF VARIABLE NON-CENTRAL LOCATIONS OF BONDED DOUBLE DOUBLER JOINT SYSTEM ON FREE FLEXURAL VIBRATIONS OF ORTHOTROPIC COMPOSITE MINDLIN PLATE OR PANEL ADHERENTS

摘要

This study investigates the "Effects of Variable Non-Central Locations of Bonded Double Doubler Joint System on Free Flexural Vibrations of Orthotropic Composite Mindlin Plate or Panel Adherents". The problem is theoretically analyzed and is numerically solved in terms of the natural frequencies and the corresponding mode shapes of the entire "System". The "Bonded Double Doubler Joint System" and the "Plate of Panel Adherents" are considered as dissimilar "Orthotropic Mindlin Plates". In all plate elements, the transverse shear deformations and the transverse and rotary moments of inertia are included in the analysis. The relatively very thin adhesive layers in the "Bounded Joint Region" are assumed to be linearly elastic continua with transverse normal and shear deformations. The "damping effects" in the adhesive layers and in all plate elements of the "System" are neglected. The sets of the "Dynamic Mindlin Equations" of both upper and lower "Doubler Plates" and the "Plate or Panel Adherents" and the adhesive layer equations are combined together with the orthotropic stress resultant-displacement expressions resulting in a set of "Governing System of PDE's" . in a "special form". By making use of the "Classical Levy's Solutions", in aforementioned "Governing PDE's" and following some algebraic manipulations and combinations, the "Governing System of the First Order Ordinary Differential Equations" are obtained in compact "state vector" forms. Thus, the "Initial and Boundary Value Problem" at the beginning is finally converted into a "Multi-Point Boundary Value Problem" of Mechanics (and Physics). These analytical results developed facilitate the present method of solution that is the "Modified Transfer Matrix Method (MTMM) (with Interpolation Polynomials)". The final set of the "Governing System of ODE's" is numerically integrated by means of the "MTMM with Interpolation Polynomials". In this way, the natural frequencies and the mode shapes of the "Bonded System", depending on the variable non-central location of the "Bonded Double Doubler Joint System" are computed for several sets of the far left and the far right "Boundary Conditions" of the "Orthotropic Plate or Panel Adherents". It was observed that, based on the numerical results, the mode shapes and their natural frequencies are very much affected by the variable position (or location) of the "Bonded Double Doubler Joint" in the "System". It was also found that as the "Bonded Double Doubler Joint" moves from the central position in the "System" towards the increasingly non-central position, the natural frequencies (in comparison with those of the central position) changes, respectively. The highly-stiff "Bonded Double Doubler Joint Region" becomes "almost stationary" in all modes in "Hard" Adhesive cases.