Abstract
In this work, the influence of uniaxial and biaxial partial edge loads on buckling and vibration characteristics of stiffened laminated plates is examined by using finite element method. As the initial pre-buckling stress distributions within an element are highly non-uniform in nature for a given loading and edge conditions, the critical loads are evaluated by dynamic approach. Towards this, a nine-node heterosis plate element and a compatible three-node beam element are developed by employing the effect of shear deformation for both the plate and the stiffeners respectively. In the structural modeling, the plate and the stiffener elements are treated separately, and then the displacement compatibility is maintained between them by using a transformation matrix. Effect of different parameters such as loaded edge width, position of loads, boundary conditions, ply-orientations and stiffener factors are considered in this study. Buckling results show that the uniaxial loaded stiffened plate with around (+30º/-30º)2 layup can withstand higher load irrespective of boundary conditions and loading patterns, whereas the maximum load resisting layup for the bi-axially loaded stiffened plate is purely dependent on edge conditions and loading patterns.
Highlights
Composite laminates belong to a category of thin-walled structures that are commonly being used in many applications like aerospace, civil, marine, and mechanical engineering structures
The results from the present investigation of the vibration and stability characteristics of S-S-S-S and C-C-C-C edged angle-ply stiffened plate under a variety of partial edge compressions can be summarized as follows: 1. It is found that for any particular ply-orientation and loading condition, the vibration frequency decreases as the intensity of edge load increases and becomes zero at the corresponding critical loads
For a plate with a single stiffener subjected to unidirectional partial edge loading, the critical load is found to be maximum at around ( 30o)2 layup irrespective of boundary conditions
Summary
Composite laminates belong to a category of thin-walled structures that are commonly being used in many applications like aerospace, civil, marine, and mechanical engineering structures. Leissa and Ayoub (1988) investigated the vibration and stability of circular and rectangular plates under concentrated edge loads acting opsite to each other using Ritz method They utilized finite element and plane elasticity solutions for obtaining the initial pre-buckling stresses, and they were the first to analyze vibration characteristics under concentrated forces. The same element has been used in this study by considering the effect of in-plane displacements u, v in addition to transverse and rotational displacements From this brief overview of the past literature, it is observed that a large body of research work has been carried out on the buckling characteristics of plates under uniform edge compression. The present work deals with the problem of vibration and buckling of stiffened composite laminates under the action of in-plane partial edge loads Analytical solution to this class of problems under such loadings is extremely difficult. A detailed parametric study is carried out to investigate the effect of different ply-angles, boundary conditions, stiffener sizes, partial edge loads, and their positions on the vibration and stability behaviour of stiffened panels
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