Analysis of couple-stresses and piezo-viscous effects in a layered connecting-rod bearing

Abstract

In this work, the combined effects of couple-stresses and piezo-viscosity on the dynamic behavior of a compression ignition engine big-end connecting-rod bearing with elastic layer are investigated using the V. K. Stokes micro-continuum theory. It is assumed that the journal (crankpin) is rigid and the big-end bearing consists of a thin compressible elastic liner fixed in an infinitely stiff housing. The governing Reynolds' equation and the viscous dissipation term appearing on the RHS of energy equation are modified using the V. K. Stokes micro-continuum theory. The non-Newtonian effect is introduced by a new material constant η, which is responsible for couple-stress property, and the piezo-viscosity effect by the pressure–viscosity coefficient α appearing in the well-known Barus' law. In the proposed model, the nonlinear transient modified Reynolds equation is discretized by the finite difference method, and the resulting system of algebraic equations is solved by means of the subrelaxed successive substitutions method to obtain the fluid-film pressure field as well as the film thickness distribution. The crankpin center trajectories for a given load diagram are determined iteratively by solving the nonlinear equilibrium equations of the journal bearing system with the improved and damped Newton–Raphson method for each time step or crankshaft rotation angle. According to the obtained results, the effects of couple-stresses and piezo-viscosity on the nonlinear dynamic behavior of dynamically loaded bearings with either stiff or compliant liners are significant and cannot be overlooked.

Shear-Thinning and piezoviscous lubricant behavior of spiral grooved hybrid thrust pad bearing configurations

“…Over the last few years, in the literature, there have been a number of investigations reported on non-Newtonian (shear-thinning and piezoviscous) lubricants, however, they are mainly limited to circular journal bearings. 10–18 Sinhasan and Sah 10 numerically investigated the static as well as the dynamic behavior of hydrostatic journal bearing by using the Finite Element Method. Further, they evaluated the performance characteristics of bearings lubricated with non-Newtonian lubricants using the cubic shear stress law model.…”

“…At higher eccentricity ratios, the power-law model's visco-metric exponent has a significant effect. Using the Stokes micro-continuum theory, Laouadi et al 14 investigated the interactive behavior of piezo-viscous effects and couple stress on the performance of a multilayer connecting rod bearing. It was reported that couple stress and piezovicous effects significantly influence the dynamic behavior of dynamically loaded bearings.…”

Combined effects of elastic deformation and piezo-viscous dependency on the performance of a journal bearing operating with a non-Newtonian fluid

“…The combined effects of couple-stresses and piezo-viscosity on the dynamic behavior of a compression ignition engine big-end connecting-rod bearing with elastic layer are investigated using the V. K. Stokes micro-continuum theory were presented by Laouadi et all. 18…”

The Effects of Ultra-Low Viscosity Engine Oil on Mechanical Efficiency and Fuel Economy

“…It was shown that the viscous compression effect needs to be taken into account when the local pressure approaches 200 MPa and the shear thinning effect cannot be neglected when the shear rate reaches 106 1/s [20]. Bouzid et al considered the combined effect of coupling stress and viscous compression effect on the dynamic characteristics of connecting rods in their study of connecting rod sliding bearings and found that the coupling stress and viscous compression effect have a significant effect on the nonlinear dynamic behavior of dynamically loaded bearings [21]. Parinam considered the shear thinning effect in the study of line contact sliding friction [22].…”