Study On Steady Thermal Slip Of Bolted Connection Structures And Dynamic Characteristics Of Non-continuous Rotor

As the most common noncontinuous structure,bolt connection structure widely exists in gasturbines and aeroengines.Too many accidents occur due to the thermal slip of bolt connection structure.Therefore,studying the contacting characteristics of bolt connection structure is the basis of ensuring strength of bolt joints,improving the accuracy of rotating machinery dynamics analysis,ensuring the security and stability of mechanical equipments.Based on the phenomenon of thermal slip of bolt connection structure,the paper analyzes the causes of thermal slip respectively in two ways,which includes the contact mechanics characteristics of bolt connection structure and coupled heat and force transfer characteristics.It studies the the influence of thermal slip between bolted flanges on dynamic characteristics of the non-continuous rotor.In the microscopic scale,it takes single asperity as analysing target to study the characteristics of contact between the rough surface.The variation of deformation of asperity and the contacting area between asperity and rigid palne with the change of loading displacment is obtained.At the same time,the regulation of the effective area of contact pressure with the related influencing factors is analyzed by finite element method,and the mathematical model of contact pressure distribution is given.For single-bolt connection structure,it builds a model of coupled heat and force transfer in steady state on the contacting intergace.The variation of the characteristics of coupled heat and force transfer with pre-tightening force of bolt,temperature and material properties is stdudied.The contact pressure distribution law of the interface and the temperature distribution law under steady state are acquired.Taking double-bolt connection structure as the target,the reasons for occurance of relative slip between the connections is analysed.It develops the force model of themal slip for bolt connection structure,and respectively study the regulation of amount of slip with bolt pretightening force,temperature difference and interface friction coefficient under uniform temperature field and non-uniform temperature field.For a non-continuous rotor of one type of aeroengine,it builds the rotor dynamics model.The influence of the bolt joint stiffness and the thermal slip on the critical speed and vibration response of the rotor was analyzed.The results can provide references for the structural design of the non-continuous rotor and the analysis of related vibration problems during operation.