Journal of Applied Sciences Research, 6(7): 905-908, 2010 © 2010, INSInet Publication Computerized Mathematical Model for Studying Geometric Shape and Stresses Applied on the Pistons’ Rings of ICE. Muntaser Momani, Sayel M. Fayyad, Suleiman Abu-Ein, Waleed Momani, and Hisham Mujafet Department of Mechanical Engineering, Faculty of Engineering Technology, Al Balqa Applied University Amman – Jordan PO Box 15008, Abstract: This work presents a computerized model for studying the geometric shape and calculating pressure (stress) applied on the piston’s ring on a given internal combustion engine. In addition the outer radius of the piston ring in the Free State will be calculated using polar coordinate system; also the maximum bending stresses created in the cross-section of the ring will be calculated. It is found that both the outer radius and the pressure distribution (maximum bending stress) have a pear shape geometry and the pressure has a maximum values as the radius becomes minimum as a function of the rotational angle ¸. Key words: internal combustion engine, ring, stress distribution, piston, Free State radius. INTRODUCTION The geometry of the pistons ring depends mostly on the pressure distribution applied on the internal surface of the cylinder, i. e. on the form of pressure distribution of the piston ring. It is known that piston rings have a pressure distribution of (pear shape) in polar coordinates, and this shape is the best distribution form since it can resist diametrical vibrations and strains. Little researches discussed this issue. H. Ahmad et al. [2] , pressures exerted by 15 in diameter rings closed to a circular shape by 36 point loads were measured with strain gauges. Departures from the theoretical open shape and from a circle when closed by tangential end forces, which simulated uniform pressure, did not predict the variations in local pressure. Double integration of pressures around the rings led to the open shape defects of the same order of magnitude as the measured values. Variations in local pressure exerted by actual piston rings can only be determined by direct, multipoint measurement[2]. S. M. Altukhov, [3] . The pressure forcing a piston ring against the cylinder wall is made up of the gas pressure and the pressure due to the elastic forces in the ring was discussed [3]. D. Walker et al. [1] described a simplified multianvil system for high pressure and high temperature experiments based on the well-established octahedron-within-cubes geometry in use in many other laboratories. Departures in designer from previous devices using this geometry include use of a loose supporting ring that accommodates appreciable elastic strain under loading from within by an unanchored cylindrical cluster of removable tool steel wedges, choice of height to diameter of the cylindrical cluster of wedges so that the negative cube geometry of the interior cavity that they surround does not have its angular relationships distorted under appreciable strain, casting of composite gasket materials directly upon low porosity octahedral pressure media[1]. Krisada et al. [5] , the compression ignition engine fueled by natural gas or Diesel Dual Fuel engine was a promising engine for the future with a higher oil price. Unfortunately, the DDF engine knock easily: this leads to damage of a piston. So, the understanding of the piston motion in the knock situation is crucial for the safe DDF engine operation. This is the first implementation of piston dynamic study focusing on the motion of the piston of DDF engine under knock situation. The simulation model was developed recently by this research group. Two sets of cylinder pressure data: original diesel mode and DDF mode under knock situation were used as input for the model. The results showed that the model can contribute the understanding of tribological phenomena of the piston lubrication. A higher peak cylinder pressure slightly increases the piston lateral motion, tilt angle, side force, and impact force. Hence, the forces from piston dynamic are not the main factor of the piston damage under the knock situation [5]. The mean (average) pressure of the pistons ring on the internal surface of the cylinder can be given as[4]: Corresponding Author: Muntaser Momani, Department of Mechanical Engineering, Faculty of Engineering Technology, Al Balqa Applied University Amman – Jordan PO Box 15008, E-mail: drsuleiman@hotmail.com 905