Research On Dynamic Modeling And Experimental Dynamic Behavior Of Mechanical Fixed Joints

The bolted fixed joints are common connection in mechanical structures, andnonlinear characteristics of joint surface is the main factor which affects the dynamicbehavior of whole machine. The method of mechanical design changes from static todynamic with the trend that modern machinery becomes high speed, high-precisionand light-weight. Moreover, calculation of dynamic behavior of machines is the keypoint to dynamic design. Therefore, the research of dynamic characteristics on thejoints has extremely vital significance to the structure design and optimization.On the macroscopic aspect,this paper analyzed the mechanism of stiffness anddamping in fixed joints, and established the equivalent dynamic model and mathematicequation; on the microscopic aspect, established a size-independent fractal model offixed joints, and then simulated the relationship between normal&tangential dynamiccharacteristics of joints and surface pressure, surface roughness as well as real contactarea by MATLAB.Considering joint influence factors, this paper designed a dynamic experimentproposal. Based on the experimental results, established a practical dynamiccharacteristic database of HT200interface in different roughness which machined bymilling and grinding; built law curves between the dynamic behavior of fixed jointsand preload, processing method of contact surface, surface roughness, interface areaand tightening method; confirmed the correctness of the theory simulation results inchapter one.This paper compared three methods of interface simulation, including Gluemethod, Contact treatment and Spring-damping simulation method, which showed thatthe third method is the most effective way to calculate the dynamic behavior of fixedjoints; and then, built a spring-damping element joints finite model based on thepressure distribution contours; based on the experimental data, simulated the model ofNO.12specimen by ANSYS; at the same time, finished a comparison among ourmodel, traditional model and experimental result, proved that the spring-dampingdistribution model based on pressure has a better simulative precision.