Abstract: To improve the prediction accuracy of the sheet metal part deformation in the simulation model of the drilling fixture location layout for sheet metal part,a fractal contact theory based method for the drilling fixture location layout for sheet metal part was proposed.The semi-elastic contact model was used to approximately replace the contact between the positioning element and the sheet metal part,and the contact stiffness and damping characteristics of contact surface were simulated by the normal spring damping unit.Then,the relationships between the normal contact force and the contact stiffness and damping were obtained by the fractal contact theory.The normal contact force at each location point was gained by finite element simulation and the contact stiffness and damping at each location point are solved.A simulation model of the location layout of the drilling fixture for sheet metal part was established and the sheet metal part deformation after drilling was predicted.The feasibility and effectiveness of the proposed modeling method were verified by two examples of flat plate and curved plate.

Key words: sheet metal part, drilling fixture, locating layout, deformation, fractal contact

摘要： 为了提高薄板件钻孔夹具定位布局仿真模型的薄板件变形预测精度,提出一种基于分形接触理论的薄板件钻孔夹具定位布局建模方法。首先采用半弹性接触模型近似代替定位元件与薄板件之间的接触,并通过法向弹簧—阻尼单元模拟接触面的刚度和阻尼特性,然后借助分形接触理论获得定位点接触区域法向接触力与接触刚度、阻尼的关系,接着在通过有限元仿真得到各定位点处的法向接触力的基础上,求解每个定位点处的法向接触刚度与阻尼,最后建立薄板件钻孔夹具定位布局仿真模型,对薄板件钻孔后的变形进行预测。通过平板和曲板两个实例验证了所提建模方法的可行性和有效性。

关键词: 薄板件, 钻孔夹具, 定位布局, 变形, 分形接触