Bearingless Rotor Hub Design Based On Flexbeam Section Optimization

Bearingless rotor is an advanced helicopter lift system while the composite3-flexible beam is animportant component for the bearingless rotor hub. The design of bearingless advanced rotor is achallenging research topic in helicopter structure design field. This paper puts forward a new style hubsystem configuration and a brand new structure optimization method for the three directional flexiblecomposite beam. It combinates the bearingless rotor hub design characteristics and optimizationtechnologies. The specific research contents are as follows:As the background, the preface briefly introduces the development course of the helicopter rotorhub system and the present research situation at home and abroad. It also points out the necessity andsignificance of beginning the design and study work for the bearingless advanced rotor hub system.In chapter2, based on variational asymptotical beam section analysis method, this chapter ismainly about the research on section characteristics analysis for large deformation composite3-flexible beam. With the aid of this method and engineering optimization software, a generalmultiobjective optimization design method determining torsion and bending section topology is set up.This method considers composite material layer design characteristics, shows originality of the bestsection configuration topology shape for each functional segment section of three directional flexiblebeam.In the third chapter, the section analysis and optimization results given in chapter3are appliedon the structure design of three directional flexible composite beam, combined with the designrequirement of bearingless rotor hub. The structure layout and sectional stiffness distribution areconfigurated for the flapwise, torsion and chordwise functional segments of the flexbeam. Theinherent dynamic characteristics of flexbeam and blade integrated model would be obtained aftercalculating the characteristics data of the model’s each section. The performance of the compositeflexbeam will satisfy various structure design requirements after repeated iterations and optimization.In chapter4, a bearingless rotor hub system overall scheme design has been completed using thescheme of flexbeam in last chapter. The advantages and disadvantages of structural loads bearingcharacteristics are analysed for this system structure with loads transfered through several pathes. Thestructure dynamics stabilities of bearingless rotor are given brief consideration.In chapter5, with the help of finite element software, the three-dimensional FEM model ofcomposite flexbeam and pitch torsion tube are build. The extreme loads needed in strength checking are determined using helicopter loads manual. The structure stress analysis is completed for strengthchecking. The calculated results also contain flexbeam dangerous sections and interlaminar shearstress, as well as the stress concentration phenomenon of composite pitch torsion tube with largeopening slot or hole.In the sixth chapter, the main research work and results are breifly introduced and the futureresearch and further prospect are put forward.