Jayashankarbabu B.S Int. Journal of Engineering Research and Applications www.ijera.com ISSN : 2248-9622, Vol. 4, Issue 8( Version 2), August 2014, pp.01-08 www.ijera.com 1 | Page Analysis of Isotropic Perforated Stiffened Plate Using FEM Shruthi H.G*, Jayashankarbabu B.S** *(Department of Civil Engineering, P.E.S College of Engineering, Mandya, Karnataka, India) ** (Department of Civil Engineering, P.E.S College of Engineering, Mandya, Karnataka, India) ABSTRACT In this paper, studied the structural instability caused by circular and square perforated plate having all round simply supported and clamped plate boundary conditions subjected to inplane uniaxial compression loading and also the strengthening effect of the stiffeners when they are reinforced to the unperforated and perforated plate in longitudinal and transverse directions. The area ratios, aspect ratios and types of stiffeners are the parameters considered. A general purpose finite element analysis software ANSYS is used to carry out the study. Results show that the presence of a central circular and square perforations causes reduction in buckling strength of plate and stiffeners can be used to compensate this reduction before it can be used to its best advantage. It is also observed that the plate strengthening effect of longitudinal stiffener is more than that of transverse stiffener for both unperforated and perforated plate. An economical design is possible by introducing stiffeners of optimum size. Keywords – Buckling load factor, Cutout, Finite element method, Inplane loads, Stiffeners. I. INTRODUCTION Plates are used in civil, mechanical and aerospace industries. Generally, in plates cutouts are provided to decrease the self-weight, to provide access from across the plate. However, though the cutouts are provided to achieve certain structural advantages, it is worth to mention here that they may inadvertently affect the stability of the plate component in the form of buckling. The presence of cutouts results in a redistribution of the membrane stresses with change in mechanical behaviors of the plates. When the cutout is inevitable for the plates under high working stress, the reduced buckling strength of the perforated plate may be insufficient to meet the requirements of normal serviceability limits and structural safety. Hence the study of stability behavior is of paramount importance. The stability of the plate always can be increased by increasing its thickness, but such a design will not be economical in respect to the weight of material used. An economical solution is obtained by keeping the thickness of the plate as small as possible and increasing the stability by introducing reinforcing stiffeners. Hence plates do need some additional flexural stiffness in the form of stiffeners. The stability of plates under various compressive loadings and boundary conditions has been the subject and studied by Timoshenko.S.P and Gere .J.M. [1] and many others. Stability of plates using the finite element method carried out by Kanwar K, Kapur and Billy j. Hartz [2]. The paper compared the buckling loads obtained by the stability co-efficient matrix approach and the available exact solutions. M R Purohit [3] investigated the structural instability caused by a plain circular perforation for simply supported square plates under edge compression and also for those plates reinforced by two symmetric stiffeners in longitudinal and transverse manner based on the principle of minimum potential energy. A.K.L.Srivastava et.al [4] have used the finite element method to study the Elastic stability of square stiffened plates with cutout under biaxial loading by assuming that the forces to act in the plane of the undeformed middle surface of the plate and the characteristic equations for the natural frequencies, buckling loads and their corresponding mode shapes were obtained from the equation of motion. The ultimate strength behaviour of longitudinally stiffened plates with openings under axial compression was studied by M. Mahendran et.al [5] using second-order elastic and rigid-plastic analyses and laboratory experiments. Effects of the size of opening, the initial geometrical imperfections and the plate slenderness ratio on the strength of perforated stiffened plates were also studied. Lars Brubak et.al [6] investigated the applicability of various strength criteria that may be incorporated into semi-analytical methods for ultimate strength prediction of arbitrarily stiffened plates in local and global bending. The present study is to exhibit the importance of providing stiffeners in enhancing the stability limits of structural plate like components under inplane uniaxial compression loading having simply supported and clamped plate boundary conditions with different aspect ratios and area ratios. To carry out the study, ANSYS software has been used with 8SHELL93 element [7]. The material of the plate is assumed to be homogeneous, isotropic and elastic with young’s modulus E=210924 N/mm 2 and Poisson’s ratio μ= 0.3. The model plate considered, RESEARCH ARTICLE OPEN ACCESS