***resolution riks

Description

The riks algorithm is a method for which local instabilities can be passed in a quasi-static analysis, such as a bucking situation of a roof collapse. Note that these “snap-though” type problems are in reality dynamic events which can also, perhaps more appropriately, be solved using implicit dynamics.

The method assumes proportional loading as well. So if the load at a point is not merely scaled through time (without change in direction) the algorithm can be used successfully.

Syntax

The syntax for Riks allows a number of keywords and keyword parameter pairs to be entered after the ***resolution command.

***resolution riks option-keys

Example

***resolution riks
    opt    4     % optimal number of iteration
    max    30    % maximum number of iteration
    div    2.    % divergence division factor
    maxDs  0.3   %
    Plus         % Keep going positive..