Program SIGMA

SIGMA is an interactive version of  program PLANT  which was developed to improve user friendliness and reduce the time required to solve a non-linear structural analysis problem.

Non-linear analyses are known to be erratic and often require special attention by the analyst in selecting the appropriate iteration parameters.  A strategy which may work well for a particular type of structural problem may easily fail when applied to a different problem.  It is not uncommon that a single problem is repeatedly restarted before a convergent solution is reached.   This can dramatically increase the total time invested by the analyst in finding the solution.

SIGMA allows the user to interactively control the iteration during solution phase.  Features for reviewing analysis results, solution accuracy and for changing iteration step size and convergence tolerance are implemented. A restart mechanism allows the analyst to interrupt the solution and to restart at any previous step.

SIGMA is a DOS based program.  A windows based version is currently being developed.

Screen layout examples of SIGMA are given below.