中文摘要：

根据板料的表面轮廓特点，建立了基于分形理论的DP780板料表面形貌模型，在表面形貌模型的基础上建立了DP780板料和模具的弹塑性接触模型，该模型将模具视为刚性体，导出了板料与模具实际接触面积的计算公式，并确定了实际接触面积与法向载荷的关系。将分形接触模型应用于摩擦模型的建立中，能够获得更为真实的边界条件，可为板料成形数值模拟的准确性提供可靠的理论基础。

英文摘要：

A surface topography model of DP780 sheet metal based on fractal theory was estab- lished. And the elastic--plastic contact model between DP780 sheet metal and die surface was estab- lished based on the sheet surface topography model. The contact model, which treated the die as rigid body, gave the calculation formula of the real contact area under different normal contact loads. Using the model to create friction model the real boundary condition can be obtained, it can improve the sim- ulation accuracy of the FEM.