Study On Modeling Method Of Bolted Joints Based On ANSYS

The bolted joint is a very common connecting form in mechanism, has a very big influence to the dynamic characteristics of the whole machine system. So, it is very necessary to study and analysis to that structure form, such as researching an available modeling method to FEA, or its effect to machine tools. But in fact, the bolted joint is a structure with some prestress, and having certain nonlinear properties. Therefore, it is awful difficult to research them.After summarizing current state of domestic and international research on bolted joint, this thesis puts forward using Virtual Joint method to build finite element model, and building up mathematics model to bolted joints.The main content of this paper is as followed:(1) This paper has summarized the state of development that the studies on dynamic performance of machine tool joints and subject matter existing at present, introduced the key method of reach on the dynamic performance of joints, and brought a new way-Virtual Joint, combined by theoretical calculation, dynamic test and FEA to research the performance of joints.(2) In the part of deducing the mathematics model of joints, using rectangle element a dynamic model of assembly structure has been deduced;(3) Using APDL language of FEA software ANSYS, an assembly model which is a whole parameterized prestressed model has been built.(4) Tacking the structural frequency of assembly model as the analysis target, this paper compared a few FEA methods through different ways to set up joints. Using virtual joint to build bolted joint is focused on in process. After qualitative analysis to parameters of virtual layer, via adopting the method combined theory study, dynamic test and FEA together, parameters of virtual layer have been identified in optimized analysis, and set up the joint's parameter equation of virtual layer.(5) Finally, in order to achieve actual modal data the shock excitation on assembly model has been tested. Lots of useful data on joints in several-normal conditions can also be found in this paper. Comparing tested data and FEA data to verify the validity and feasibility for using virtual joint to build assembly model.By means of experiments and FEA calculation, this thesis achieved the validity and feasibility to model and analysis. The study of this paper provided an easy and valid approach to set up assembly model with joints. Research indicates that, given appropriate parameters of virtual layer we can get the dynamic model of assembly including joints, which reflects the actual characteristic of joint.Some basic theories of finite element and model testing are included in this paper; they are needed to understand this paper. The paper also covers some ANSYS study on dynamic characteristics of joints.