isgfdi
Civil/Environmental
- Jun 12, 2014
- 2
Hi,
I am doing a seismic analysis with an acceleration time history (TH) imposed to the nodes which are attached to the ground. The acceleration TH is given at time steps of 0.02 seconds. In order to capture all peak values of this acceleration TH I have set the "initial" and "maximal" "Increment size" equal to 0.02. If ABAQUS encounters numerical difficulties, the increment size is decreased automatically. In the further calculation the increment might be increased again to the maximum. However, due to the varying increments, the input is not at the defined time increments of exactly 0.02 seconds. Thus, peak values might be omitted and the applied acceleration time history is different from the defined one. See also the attached diagram for visualization.
The question is now, how can I enforce that all peak values are taken into account?
Of course the "Type" of "Incrementation" might be set to "Fixed" with an increment of 0.02 - however then ABAQUS encounters convergence difficulties without being allowed to decrease the increment size and aborts the calculation (error message: "Fixed time increment is too large"). Also, of course I could set the fixed time increment to a much more smaller value - but this would be a computational very uneconomic solution.
What would be needed is let's say allow Abaqus to decrease & increase automatically the increment size, however enforce Abaqus to calculate all specified data points of the inputted acceleration time history! Is there any option like this or any workaround?
Thanks in advance.
I am doing a seismic analysis with an acceleration time history (TH) imposed to the nodes which are attached to the ground. The acceleration TH is given at time steps of 0.02 seconds. In order to capture all peak values of this acceleration TH I have set the "initial" and "maximal" "Increment size" equal to 0.02. If ABAQUS encounters numerical difficulties, the increment size is decreased automatically. In the further calculation the increment might be increased again to the maximum. However, due to the varying increments, the input is not at the defined time increments of exactly 0.02 seconds. Thus, peak values might be omitted and the applied acceleration time history is different from the defined one. See also the attached diagram for visualization.
The question is now, how can I enforce that all peak values are taken into account?
Of course the "Type" of "Incrementation" might be set to "Fixed" with an increment of 0.02 - however then ABAQUS encounters convergence difficulties without being allowed to decrease the increment size and aborts the calculation (error message: "Fixed time increment is too large"). Also, of course I could set the fixed time increment to a much more smaller value - but this would be a computational very uneconomic solution.
What would be needed is let's say allow Abaqus to decrease & increase automatically the increment size, however enforce Abaqus to calculate all specified data points of the inputted acceleration time history! Is there any option like this or any workaround?
Thanks in advance.