ISSN: 2319-8753 International Journal of Innovative Research in Science, Engineering and Technology Vol. 2, Issue 7, July 2013 Copyright to IJIRSET www.ijirset.com 2903 ANALYSIS AND MITIGATION OF STRESS CONCENTRATION FACTOR OF A RECTANGULAR ISOTROPIC AND ORTHOTROPIC PLATE WITH CENTRAL CIRCULAR HOLE SUBJECTED TO IN-PLANE STATIC LOADING BY DESIGN OPTIMIZATION Shubhrata Nagpal 1 , Dr. S. Sanyal 2 , Dr. N.K.Jain 3 Associate Professor, Department of Mechanical Engineering, Bhilai Institute of Technology, Durg (C.G.), India 1 Professor and Head, Department of Mechanical Engineering, National Institute of Technology, Raipur (C.G.), India 2 Assistant Professor, Department of Mechanical Engineering, National Institute of Technology, Raipur (C.G.), India 3 Abstract: A number of analytical and numerical techniques are available for the two dimensional study of stress concentration around the hole(s) and notches in isotropic and orthotropic plates subjected to in-plane or transverse loading conditions. The influence of the structural dimension D/A (where D is hole diameter and A is plate width) ratio upon stress concentration factor for different cases is studied in the present work. Peculiarity in Stress concentration factor for different stresses like  x ,  y ,  xy ,  von and deflection for different materials is observed. Stress concentration factor for all stresses shows marked mitigation upon introduction of auxiliary holes. Finite element method has been adopted for analysis and the results have been presented in graphical forms with discussion. The finite element formulation and its analysis are carried out using ANSYS package. This research work can provide structure engineers a simple and efficient way to estimate the effect of SCF and its mitigation in plate structures made of isotropic and orthotropic materials. Key words: Finite Element Method, Stress Concentration Factor, Orthotropic Material, Mitigation of Stress Concentration Factor. NOMENCLATURE A Width of plate (m) D Diameter of hole (m) E x Modulus of elasticity for X direction G xy Modulus of rigidity for XY plane σ Uniformly distributed load (N) K t SCF, Stress concentration factor = σ max / σ nom L Length of rectangular plate, m L 1 Distance between centre of main hole and first set of auxiliary holes L 2 Distance between centre of main hole and second set of auxiliary holes R 1 Radius of first set of auxiliary holes, m R 2 Radius of second set of auxiliary holes, m t Thickness of plate (m) def i Deflection in i direction in plate with hole def ij Deflection in ij direction in plate with hole σ X Normal stress in X direction σ Y Normal stress in Y direction σ VON Von - misses stress τ XY Shear stress in XY plane Ҝ 1 Percentage reduction in SCF for stress in X direction with one set of auxiliary hole Ҝ 2 Percentage reduction in SCF for stress in X direction with two set of auxiliary hole I.INTRODUCTION A rectangular plate with a central hole have found widespread practical applications in various fields of engineering such as aerospace, marine, automobile and mechanical and is familiar to most engineers. High stress due to discontinuity or abrupt change in geometry is known as stress concentration and mostly found at the edges of discontinuity. A stress concentration is typically introduced in plates in the form of circular holes. Most of the strength analyses involving SCFs are based on the conditions of infinite-width/diameter plate because closed form stress distributions are available. For the design of plate with a hole, accurate knowledge of stresses and stress concentration factor (SCF) at the edge of hole under in plane loading are required. As a result, stress distribution is not uniform