The six degrees of freedom(6-DOF) excitation platform is an important ground apparatus in the multi-axes vibration environment simulation. Because of its complex structure and multiple degrees of freedom of motion, it is difficult to build an accurate structural dynamic model. Based on the structural dynamic characteristics of the 6-PSU platform, a parametric modeling and model updating method is proposed. Firstly, the joints and the moving parts are regarded as the model modification objects, since they have their contact interfaces included in the bearings and the linear guides. And their equivalent dynamic models could be established with the proposed decoupling method for their stiffness and mass. Secondly, on the basis of the equivalent dynamic model, the beam cross section parameters for the structures of the joints and the moving parts are updated by using of the structural modal information. After that, the contact stiffness coefficients are revised using the frequency response function(FRF). Through the above steps, the updated finite element model for the 6-DOF platform is built. The comparison between the calculation based on the model and the FRF test show that the modeling approach is effective and valid.%六自由度激励台是多轴同步振动环境模拟的重要地面设备,因其结构复杂且具有多个运动自由度,而难以构建准确的结构动力学模型.文章针对6-PSU构型激励台的结构动力学特性,提出其参数型建模与模型修正方法.首先确定模型修正的对象为含轴承和导轨等接触运动副的铰链与作动部件,提出采用刚度与质量解耦的方法建立其含参等效动力学有限元模型;然后以该等效模型为基础,通过模态参数修正铰链和作动部件等效梁模型参数,再利用频响函数修正模型中轴承和导轨的接触刚度参数,得到了修正后的激励台等效结构动力学模型.修正后的有限元模型计算结果与试验结果吻合较好,验证了建模方法的有效性.
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