Paper Title
Chaotic Study of Dynamic Stability in Spindle Shaft Using Couple Stress Fluid as Lubricant

In this study the dynamic analysis of spindle motion in lathe machines which act as rotor bearing system is studied. Work piece is supported between two ends which act as two fluid film journal bearings lubricated with couple stress fluid. Theory of short bearing is used. The model consists of non-linear system of rotor equations of motion. A generalized Reynold’s equation is derived for the selected system of rotor bearing and non-dimensional parameter ‘l’ is used for couple stress fluid. Dynamic trajectory, Poincare maps, and Bifurcation diagrams are used to analyze the behaviour of the rotor center and bearing center by using Range-Kutta method. The periodic, quasi-periodic, sub-harmonic and chaotic motion are demonstrated in this study. Results show that the dynamic stability of system depends on rotor speed and degree of rotor unbalance and is enhanced by using the couple stress fluid as lubricant as compared to the Newtonian fluid. Index terms- Journal bearing, dynamic analysis, stability, couple stress fluid, Bifurcation