Study On Dynamic Characteristics Of Bolted Disk Rotor System

There are a variety of interconnected structures in various dynamic and static parts of the aero-engine,such as splines,curvic couplings,seam allowance and bolted structure,etc.In the rotor system of aero-engine,bolted structures are often used to connect all levels of the disk and drum structure,forming the bolted structure of the disk-and-drum rotor.In the bolted structure of the disk-and-drum rotor,it is difficult to build accurate model of the contact stiffness of the bolted connection position,so ensuring computational efficiency is hard in engineering applications.Taking the aircraft engine as the research background and the bolted disk-and-drum rotor as the main research object,this paper starts with the local structure and apply the research results to the whole structure to study its dynamic characteristics,specifically as follows:Firstly,based on the analysis of the structure of the aero-engine disk-and-drum rotor system,three experimental structures are established for its connection characteristics,which are: "sector disk" structure," integrated sector disk and drum " structure and "the bolt structure of the sector disk and drum”.And the test rig is built for testing inherent characteristics of the sectorial disk-and-drum structure connected by single bolt.By comparing the results of the inherent characteristics experiment and simulation,the accuracy of modeling and calculation boundary conditions of the disk-and-drum structure is verified.Secondly,the contact characteristics of the sectorial disk-and-drum structure connected by single bolt were simulated.Based on the distribution characteristics,shown by the simulation results,of the equivalent stress cloud map of bolt connections between the main contact surface of the low pressure drum and the middle disk as well as the high pressure drum and the middle disk,the zonal double-loop thin layer element is inserted between the main contact surfaces to establish the finite element model of the sectorial disk-and-drum structure connected by single bolt based on the thin-layer element.Based on the theory of thin-layer element method,the variation law of the natural frequency of the whole structure with the change of the elastic modulus of thin-layer element was obtained by changing the elastic modulus of thin-layer element to simulate the bolt preload change,which provided the simulation data basis for establishing the contact stiffness model.Then,the inherent characteristics of the ‘the bolt structure of the sector disk and drum’were tested,and the variation rule of the first six order natural frequencies with the bolt preload was obtained,which provides the basis of the experimental data for the contact stiffness model.The square error ratio function between simulation results based thin-layer element and experimental data is established to realize the accurate identification of the contact stiffness.The inherent characteristics of the structure are simulated based on the thin layer element method.Finally,the obtained contact stiffness model is applied to the existing bolted structure of the full disk-and-drum rotor in the laboratory and the accuracy of the application is verified.Then it is applied to the whole-circle bolted disk-and-drum rotor system tester,to calculate the inherent characteristics and the unbalance response by simulation and investigate the factors affecting rotor dynamic characteristics.And the experiments on the inherent characteristics and dynamic response of the whole-circle bolted disk-and-drum rotor system were carried out.