COUETTE DOMINANCE USED FOR NON-NEWTONIAN ELASTOHYDRODYNAMIC LUBRICATION

The perturbational approach that assumes Couette dominance in non-Newt onian elastohydrodynamic lubrication analysis is discussed. The assump tion is found valid for non-Newtonian fluid models exhibiting Newtonia n properties at low shear strain rate. A general non-Newtonian fluid m odel which meets that requirement is incorporated into elastohydrodyna mic lubrication analysis of line contacts by using the perturbational approach. In the case of a circular-fluid model the results obtained f rom the perturbational approach are in good agreement with those obtai ned from the direct approach. However, a better convergence and the po ssibility of avoiding using stress boundary conditions at high shear s tress can be achieved by using the perturbational approach. Results ar e presented for various values of the shape exponent in the general mo del, and it transpires that this also is an important parameter of the fluid model.