Lightweight Design And Vibration Analysis Of Aviation Starter Generator Structure

The initial state of the aviation starter generator is used as a motor.When the engine reaches a certain speed,it enters the power generation state.Combining the original starter and generator performance,it is gradually widely used in the aviation field.Because the starter generator works in an aerospace vehicle,it must meet the special requirements of the aircraft,such as small size,light weight,and reliable operation.In addition,the starter generator is connected to the high-pressure rotor of the turbine engine,and when the engine is running normally,the vibration is directly transmitted to the starter generator.Therefore,it is necessary to analyze the vibration and stress of starter generators under external vibration sources to improve the reliability of aviation starter generators.This paper analyzes the design and structural optimization of aviation starter generators.The specific work research content is as follows:First,according to the working environment and requirements of the starter /generator,a basic electromagnetic scheme is designed,including the selection of the pole slot coordination of the motor,the design of the winding scheme,the selection of the stator slot type,the selection of the rotor structure,the selection of permanent magnet materials and the determination of the specific parameters of the motor.Through theoretical analysis,the analytical formula of radial air gap flux density and the expression of radial electromagnetic force are derived,the main harmonic components of radial electromagnetic force are analyzed,and the electromagnetic simulation analysis of the motor is carried out by means of finite element method,so as to verify the rationality of the electromagnetic scheme design of the motor and the theoretical analysis of electromagnetic force.Secondly,the modal analysis and calculation of the stator system of the starter generator are carried out.The first six-order radial natural frequencies and mode shapes of the stator core are obtained through simulation.It is found that the frequency of the radial electromagnetic force of the motor is quite different from the radial natural frequency of the iron core,and it is determined that the motor itself willnot have electromagnetic resonance.The modal analysis of the starter-generator machine under constrained conditions is performed to determine whether the motor will produce a resonance phenomenon with the turbine engine.The modal superposition method is used to analyze the stress of the motor under the excitation source of the turbine engine and calculate dynamic stress and displacement of key components of the motor.Finally,through the comparative analysis of the properties and characteristics of each material,a lightweight and high-strength 7075 aluminum alloy is selected as the material of the motor casing and the end cover,and by using the ANSYS Workbench structure optimization module to take the total thickness of the front end cover,the weight reduction hole diameter and the hole depth of the motor as input parameters to study its influence on the maximum stress and maximum displacement of the front cover.On the premise of ensuring the strength of the motor,the structure of the mechanical parts of the motor is optimized to reduce the quality of the motor.