Digital twin of the rotor-shaft of a lightweight electric motor during aerobatics loads

Abstract

PurposeThis paper aims to present airworthiness considerations regarding a shaft of an electric motor. A fatigue lifetime prediction analysis based on one-step load spectrum is performed during high-cycle fatigue. Time-dependent normal and shear stress components are estimated using a high-fidelity digital twin built in Siemens PLM Nx Nastran as a finite element model (FEM). Linear and centrifugal acceleration as well as gyroscopic moment, motor torque, propeller thrust and thermal loads are considered. The equivalent cyclic degree of utilisation and a safety margin against the slip of a press-fitted shaft to rotor hub connection is estimated.Design/methodology/approachA load analysis using FEM is presented. The numerically obtained results are verified on an analytical and a semi-empirical basis.FindingsThe shaft of the electric motor can sustain 74 h of operation if burdened with aerobatic loads. Its load capacity equals 48% for the overall safety factor of 2.25.Practical implicationsThe paper presents a specific, easily identifiable advance in knowledge that can be applicable in safety flight analysis issues.Originality/valueThe work presents a rotor of a novel lightweight electric motor for aircraft applications, which is a successor of the electric motor set recently in Extra 330E. The work delivers a computational estimation of the shaft life.