Research On Dynamic Properties Of Bolted Joints Based On Virtual Material

Bolted fastening is the most widespread fastening means in mechanical system,it destroy the continuity of structure,which greatly affects the dynamic properties of the structure.Establishing dynamic model which could characterize dynamic properties of bolted joints and identifying dynamic parameters of bolted joints accurately are the key to constructed dynamic model of system as well as the base to analyze,predict and optimize dynamic properties of the system.Investigating vibration energy distribution and transmission path,which have great influence on stability and precision retaining ability of mechanical system,is of great significance.Thus,the work in this paper is as follows:(1)A equivalent bolted joints dynamic model based on virtual graded material which considering contact press distribution of joint surfaces is put forward.The principle and expression of virtual graded material model combining fundamental dynamic propertie parameters and contact press distribution are also determined.(2)A kind of element used to calculate static properties,dynamic time history response and mode of structure with graded material is developed based on ABAQUS user subroutine;The accuracy of user defined element is verificated by compared the calculation results of different objects using user defined elements and standard element;influence of material parameters on dynamic properties of structure with graded material is also analyzed.(3)Bolted joint testpiece is designed and its modal parameters are obatained by experimental modal analysis.(4)The initial range of virtual material parameters to be idenfied is determined first;Surrogate models is constructed combining experimental and simulation modal parameters next;Parameters of virtual material are idenfied through genetic algorithm based on Kriging model with highest precision,performance of dynamic model using different virtual material is then compared;Finally,influence of virtual material parameters on dynamic properties of testpiece is o analyzed.(5)Virtual graded material model is applied on column-bed joints of machining center,its accuracy is verified by comparing experimental and simulation modal analysis of machining center;Dynamic properties,energy distribution and transmission path of machining center under typical condition is analyzed,which could be conducive to optimization and vibration control of structure.