Dynamic stiffness characteristics of aero-engine elastic support structure and its effects on rotor systems:mechanism and numerical and experimental studies

The support structure of a rotor system is subject to vibration excitation,which results in the stiffness of the support structure varying with the excitation frequency(i.e.,the dynamic stiffness).However,the dynamic stiffness and its effect mechanism have been rarely incorporated in open studies of the rotor system.Therefore,this study theoretically reveals the effect mechanism of dynamic stiffness on the rotor system.Then,the numerical study and experimental verification are conducted on the dynamic stiffness characteristics of a squirrel cage,which is a common support structure for aero-engine.Moreover,the static stiffness experiment is also performed for comparison.Finally,a rotor system model considering the dynamic stiffness of the support structure is presented.The presented rotor model is used to validate the results of the theoretical analysis.The results illustrate that the dynamic stiffness reduces the critical speed of the rotor system and may lead to a new resonance.

Reform and Innovation of Education and Teaching in the Information Age--Comment on “Research on Education and Teaching Theory and Practice in the Information Age”

This paper takes“Research on Education and Teaching Theory and Practice in the Information Age”as the main research object,and discusses the importance and influence of education and teaching reform and innovation in the information age.First,it introduces the background of education in the information age,including the characteristics of the information age and the development status of education.Secondly,it summarizes the main content of the book“Research on the Theory and Practice of Education and Teaching in the Information Age.”Lastly,the key points of education and teaching reform in the information age are discussed in order to provide effective guidelines and support for the practice of future education and teaching reform.

NaSICON:A promising solid electrolyte for solid-state sodium batteries

A surge of interest has been brought to all-solid-state batteries(ASSBs)as they show great prospects for enabling higher energy density and improved safety compared to conventional liquid batteries.Na Super Ionic CONductors(NaSICONs)proposed by Goodenough and Hong in 1976 are the most promising materials class for Nabased ASSBs owing to their excellent ion conductivity(>1mS cm−1),high thermal and chemical/electrochemical stability,as well as good chemical/electrochemical compatibility with electrode materials.The major challenge facing NaSICONtype electrolytes is the generally high interfacial resistance and thus sluggish charge transfer kinetics across the NaSICON/cathode interface.Great endeavors in the past few years have led to progress in the improvement of the ion-conducting property,and a dramatic decrease in the NaSICON/electrode interface resistance.Excellent cycling performance and rate capability have been achieved through interface engineering.In this review article,we summarize the state-of-theart findings for various derivatives of NaSICON structured solid electrolytes,with the aim of providing a deeper understanding of the underlying mechanism for the improvement of ion conductivity,and the intrinsic reasons for the enhanced interface charge transfer kinetics.These strategies can be readily extended to other solid electrolytes.We hope this review will inspire more work on NaSICONtype solid electrolytes and solid-state batteries.