Setting Newton-Raphson method

With the Newton-Raphson method the course of iteration can be driven by setting the following parameters:

1) Relaxation factor – it represents the value of reduction of the current load step for the restart providing the solution fails to converge. A new value of the assumed load step is found from the expression:

new load step = old load step / relaxation factor.

2) Max. No. of relaxations for a single load step – this parameter determines how many times it is possible to invoke the above action during the entire analysis. Exceeding this value prompts the program to terminate the analysis. The results are then available for the last successfully converged load level.

3) Min. No. of iterations for a single load step – this parameter allows for possible acceleration of the analysis. In particular, providing the number of iterations to converge in the last load step is less than the minimum one set, the load step for a new load increment is increased as follows:

new load step = old load step * relaxation factor.

The default setting of the above parameters corresponds to values displayed in the figure:

Parameters driving the iteration process