Search results

Argues that the dynamic‐explicit approach has in recent years been successfully applied to the solution of various quasi‐static, elastic‐plastic problems, especially in the metal forming area. A condition for the success has, however, been that the problems have been displacement‐driven. The solution of similar force‐driven problems, using this approach, has been shown to be much more complicated and computationally time consuming because of the difficulties in controlling the unphysical dynamic forces. Describes a project aiming to develop a methodology by which a force‐driven problem can be analysed with similar computational effort as a corresponding displacement‐driven one. To this end an adaptive loading procedure has been developed, in which the loading rate is controlled by a prescribed velocity norm. Presents several examples in order to exhibit the merits of the proposed procedure.

Several mechanical models can be employed for the analysis of thin walled structures. A bending indicator is developed for a nonlinear adaptive process and applied to thin walled axisymmetric shell problems incorporating membrane and bending elements. If the structural response of the model including bending is available the error made by the reduced membrane model is easy to evaluate. Thus an indication for the bending has to be found from the structural response of the reduced membrane model. This is done by an approximation of the rotations of the membrane part of the structure and by an evaluation of the bending energy leading to the bending indicator with these approximated rotations. Finally a criterion for the change of the models is proposed based on the bending indicator and some examples are presented.