Modeling and validation of spindle shaft followed by goal driven optimization

Abstract

The spindle bearing system is critical component in any machining center due to its complexity and it directly affects design or selection of components. Fail-safe design is traditional design philosophy of the machine centers which leads to over-sized machine tool design including spindle bearing system. Over-sized spindle design affects the performance characteristics of the machine center and should be optimized. Therefore, this work presents a methodology for design optimization of spindle shaft that is subjected to uniformly distributed load. The deflection distribution of shaft due to given loading condition is a way for controlling the stability of spindle and its failure. In this work analytical as well as numerical methodology is presented for modeling and validation of spindle shaft deflection. The analytical modeling of spindle uses conventional beam theory whereas numerical modeling uses finite element analysis (FEA) software ANSYS. Analytical model is validated by performing static structural analysis using BEAM188 element and used further to calculate optimum bearing spacing for minimum deflection. Finally, analytically calculated optimum bearing span is used as design variable with specific range. Thus, a goal driven optimization (GDO) is performed in ANSYS with mass reduction as an objective function and deflection as design constraint.