Finite element model updating of multi nozzle ejector based on response surface method
                                        YANG Yi sheng, LIU Zong zheng, MA Yue yin, YAN Xi qiang, WANG Yuan xing, XIE Qiang
                                                 （China Aerodynamics Research and Development Center, Mianyang 621000, China ）


Abstract: Aiming at the problems that prediction of the dynamic response of a multi nozzle ejector under the action of pulsating load, the finite element model was updated to reduce the influence of material properties and boundary conditions on the calculation results. Firstly, the finite element modal analysis of the ejector was carried out to obtain the initial modal analysis frequency. Secondly, the hammering modal test on ejector was done using multi input multi output analysis method to get the modal test frequency of ejector. Thirdly, based on the finite element model error analysis, the correction parameters such as material density, elastic modulus and quality of mass point were determined. After the sample space was determined by the central composite design method, the multi objective response surface was constructed and used to obtain the optimal solution of the correction parameters. Finally, the optimal correction parameters were used for finite element analysis to obtain the corrected modal analysis frequency and dynamic response under the real load. The results indicate that the error of the first three modes between the corrected modal analysis frequency and the modal test frequency is reduced from 8.01% to 2.81%, so the updating method can significantly improve the precision of the finite element modal analysis.
Key words: multi nozzle ejector; response surface; modal test; modal analysis; model updating