RESEARCH ARTICLE Walha LASSAAD, Tounsi MOHAMED, Driss YASSINE, Chaari FAKHER, Fakhfakh TAHER, Haddar MOHAMED Nonlinear dynamic behaviour of a cam mechanism with oscillating roller follower in presence of profile error © Higher Education Press and Springer-Verlag Berlin Heidelberg 2013 Abstract In this paper we investigate the nonlinear dynamic behaviour of a cam mechanism with oscillating roller follower in presence of defects. The nonlinear developed lumped-mass model includes eight degrees of freedom with two nonlinear hertzian contacts. The first one is located between cam and first roller while the second is between second roller and the sliding rod. The nonlinear dynamic behaviour is described by second order differ- ential equations which are resolved by using the implicit Newmark algorithm combined with the Newton-Raphson iterative scheme. The influence of the cam profile error on the dynamic behaviour is also investigated. Keywords cam, nonlinear behaviour, oscillating roller follower, profile error 1 Introduction Cam followers are mechanisms which transfer power from a rotating driving system to a translating system. There are widely used and popular in many industrial applications. These mechanisms are characterized by few moving parts and can be built with very small size. Generally, the three main components of the can mechanism are: a cam, the driving element; a follower, the driven element and a fixed frame [1]. The application of cam-follower mechanism in internal combustion engines provides the simplest way of achiev- ing almost any desired follower motion. Sometimes, this system is used in almost every mechanical system to transmit a desired motion to another mechanical element by direct surface contact [2]. Most researchers used lumped parameters dynamic models to simulate the dynamic behaviour of cam mechanism and focused mainly on those using sliding followers [3–5]. Despite the importance of cam mechanism with oscillating roller follower (for example the control of opening and closing of valves in internal combustion engines), we are interested on its dynamic behaviour. In this paper a theoretical formulation to describe the nonlinear dynamic behaviour of a cam mechanism with oscillating roller follower is presented. A lumped para- meters model with eight degrees of freedom is developed. The nonlinear dynamic behaviour is described by a system of non linear second order differential equations. The dynamic responses are obtained through a coupling between the implicit Newmark algorithm with the iterative Newton-Raphson method to iterate the solution for each time step. 2 Dynamic modeling of the cam mechanism with oscillating roller follower Figure 1 shows the cam mechanism with oscillating roller follower studied in this paper. This mechanism consists of a cam (1) mounted on a camshaft, an oscillating follower (3) with 2 rollers (2) and (4) and a sliding rod (5) that translate vertically. A spring is inserted between the sliding rod (5) and the frame to maintain two contacts at points C 1 and C 2 . Cam (1) rotates at a constant angular velocity ω 1 . This rotation causes the oscillation of the follower (3) relatively to a fixed point O 3 and hence the translation of the sliding rod (5). We suppose that we have always two contact points C 1 and C 2 between the roller (2) and Cam (1) and between the roller (4) and the sliding rod (5) respectively. Figure 2 represents the nonlinear dynamic model of the Received October 17, 2012; accepted March 7, 2013 Walha LASSAAD (✉), Tounsi MOHAMED, Driss YASSINE, Chaari FAKHER, Fakhfakh TAHER, Haddar MOHAMED Research Unit of Mechanical Dynamic System (UDSM), Mechanical Engineering Department, National Engineers School of Sfax, University of Sfax, Tunisia E-mail: walhalassaad@yahoo.fr Front. Mech. Eng. 2013, 8(2): 127–136 DOI 10.1007/s11465-013-0254-x