Journal of Experimental & Applied Mechanics Volume 3, Issue 1, April 2012, Pages 1-16 ______________________________________________________________________________________ ISSN: 2230–9845© STM Journals 2012. All Rights Reserved Page 1 A New Numerical Method for the Analysis of Stress Concentration in Tension Specimen Muhannad Mustafa 1,2 *, Nusrat J. Chhanda 1 , M. A. Salam Akanda 1 1 Department of Mechanical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka, Bangladesh 2 Present Address: Department of Mechanical Engineering, Auburn University, AL 36849, USA *Author for correspondence E-mail: mzm0020@auburn.edu 1. INTRODUCTION Advanced injection molding becomes one of the popular methods for mass production of particle reinforced plastic composites due to low production cost. ASTM D 638 [1] is a standard test method for tensile test of plastics and also particle reinforced plastic which has been widely used in many commercial and research industries. From tensile strength evaluation test, it is observed that fracture always initiates at a location where gage section ends and curved transition region begins. This type of failure always causes problem to evaluate actual tensile strength of material as failure due to stress concentration may underestimate the tensile properties. It has been noticed in previous research works [2–4] that presence of high percentage Nd-Fe-B particles causes brittleness of plastic material. Although ductile material like pure Nylon-11 can overcome the problem of forming crack at the location of initial stress concentration because of large plastic deformation. Due to recent demand of strong plastics, production of particle reinforced plastics increases rapidly, whereas these types of plastic materials are often highly brittle. This becomes a major issue of concern for many researchers, as failure due to stress concentration is obvious ABSTRACT Analyzing the stress concentration in the critical region of a mixed boundary value elastic problem has always been an important area of interest in applied mechanics. In most of the cases, the problems were circumvented using a numerical solution. A numerical approach has been used to solve elastic problems of arbitrary shaped bodies subjected to mixed boundary conditions. The formulation of displacement potential function is used in finite difference method to determine the stress concentration factors in the critical point of fillet region of tension specimen. In this paper, ASTM D 638 type І, II, III, IV and specimens of other proposed dimensions are analyzed. A relationship between stress concentration factor and width-fillet ratio (w/r) has been established. It is also observed that width ratio (W/w) has no effect on stress concentration factor for higher fillet radius. But for lower fillet radius, width ratio has significant effect on stress concentration factor. It is suggested that single arc tension specimen (ASTM D 638 type I, II, and III) can be used instead of double arc specimen (ASTM D 638 type IV) since complicated geometry of double arc tension specimen cannot help to reduce stress concentration in the specimen during tensile test. The results obtained have been presented graphically and are in good agreement with the available results in the literature. Keywords: Finite difference technique, Displacement potential function, Stress concentration factor