An alternative scheme for the corner–corner contact in the two-dimensional Discontinuous Deformation Analysis

Formulated based on the discrete block system, the Discontinuous Deformation Analysis (DDA) requires an accurate contact analysis between discrete blocks. Among the various contacts, the modeling of the corner–corner contact is the most challenging one as the contact reference edges in the corner–corner contact are not unique, which may lead to an indeterminate state in the numerical analysis. The algorithm in the original DDA employs the penetration distance to determine the contact edge in the corner–corner contact, which may not work for cases where two corners are detected in contact but without a penetration. An enhanced algorithm for choosing the initial contact edge of the corner–corner contact in the DDA is presented in the paper, in which a special contact spring that works like a weak “pin joint” is added between the contact corners. The relative moving tendency is determined under the special contact spring, so that the program can automatically choose a reasonable contact reference edge for the corner–corner contact. Three numerical examples are used to illustrate the advantage of this alternative method over the original DDA code.