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This paper aims to propose a new hydrostatic squeeze film damper compensated with electrorheological valve restrictors to control the nonlinear dynamic behavior of a rigid rotor caused by high unbalance eccentricity ratio. To investigate the effect of electrorheological valve restrictors on the dynamic behavior of a rigid rotor, a nonlinear model is developed and presented.

The nonlinear results are compared with those obtained from a linear approach. The results show good agreement between the linear and nonlinear methods when the unbalanced force is small. The effects of unbalance eccentricity ratio and electric field on the vibration response and the bearing transmitted force are investigated using the nonlinear models.

The results of simulation performed that the harmonics generated by high unbalance eccentricities can be reduced by using hydrostatic squeeze film damper compensated with electrorheological valve restrictors.

The numerical results demonstrate that this type of smart hydrostatic squeeze film damper provides to hydrostatic designers a new bearing configuration suitable to control rotor vibrations and bearing transmitted forces, especially for high speed.

The fatigue, thermal and wear-based bearing lives are the most important factors in the design of spherical roller bearings (SRBs). The main novelty of the present work is consideration of thermal effects as an additional objective function. The dynamic capacity (Cd), the elasto-hydrodynamic minimum film thickness (h_min) and the maximum bearing temperature (T_max) are related directly with overall lives of the bearing, and these constitute the multiple tasking operating requirements for the design of bearings.

These tasks depend upon various bearing design variables and associated constraints to help in formulating the realistic design optimization problem and in the present work these have been used to get optimal designs of SRBs in the form of Pareto-optimum fronts by using genetic algorithms.

The optimized lives show higher values as compared to the standard lives and better design choices as compared to that are available in the literature. The robustness of obtained designs are shown by conducting the sensitivity analysis of optimized operating requirements by perturbing optimum bearing variables.

The robustness of the design could be improved by optimizing tolerances of design variables based on desired variation in multiple tasking operating requirements.

For the aerospace and space applications such critical design of bearings are required based on multiple tasking operating requirements. For example for higher temperature application in gearboxes, turbines and drilling equipment.

In critical applications, multiple tasking operating requirements are essential and often bearings put limit to the life of satellites and aircraft, and bearing design methodology proposed and implemented in the present paper addresses these issues, especially addition of thermal issue in bearing design.