Abstract: Using a rough body-rigid plane contact model, the accuracy of the general normal stiffness equivalent method of contact interface is analyzed under both elastic and elastic-plastic material. The results show that there is a significant error while dealing with elastic-plastic materials, and the essential reason is that the general equivalent method cannot consider the plastic effect of materials completely. By making the elastic-plastic contact system equivalent to an interfacial contact layer and a non-interface block, the original system can be accurately equivalent, because the contact layer includes all the plastic effect. However, introducing the contact layer with a certain thickness can bring the problem of enlarging more elements and inconvenience for practical engineering. In order to overcome the weakness, a new equivalent method of normal contact stiffness is presented by separating the normal stiffness of the contact layer further. Using this method, the contact system is equivalent to non-thickness homogeneous spring and an elastic-plastic block with original size. In this way, the original system can be accurately equivalent, and the plastic effect of the contact body can be taken into account completely. Furthermore, the new equivalent method has nothing with the thickness of plastic zone, so it is convenient for meshing the original system. The results of typical example show the accuracy and effectiveness of the new method.

Key words: Contact, Equivalent method, Interface, Normal stiffness