2-step simulation with history results

Hi everyone,

I want to simulate the dynamic response of a pre-stretched membrane under external loads. As suggested in:

I plan to have 2 steps.
In the first simulation, I stretch the membrane to the desired length. Then, I’ll use the results as the initial condition of the second simulation, this may include saving the strain, stress, and deformation of the membrane in step one.

Does anyone have ideas on how to achieve this goal?

You may start from the simplest example of stress stiffening - a cable. This will give you the most predictable results. If you model a truss element and apply tension to it, the element should gain bending stiffness. At least that’s how it works in other FEA codes.

Or you can go directly to membranes since their behavior is also quite straightforward. In fact, if you want to model a membrane, CalculiX has special elements for that so you don’t have to use regular shells. Load the membrane in tension and you should be able to bend it in the second step.

All that assuming that you will enable NLGEOM, don’t forget about it as that’s the crucial setting here.


Thanks, it sounds great. The problem is after I get the results in the first step, I don’t know how to put them into the second step. Do you have any guidance or references about the procedure? You are very much appreciated!

The results will be automatically carried over to the second step. That’s the whole idea of using multiple subsequent non-perturbative steps - the starting condition in each static step is the ending condition from the last static step. So the model evolves throughout the steps in which you define the whole history of loading.

Thanks, I’ll try it. By the way, what I need is a dynamic simulation, it the procedure the same as it in the static simulation?

Yes, the same rule applies to dynamic implicit and dynamic explicit simulations. Only perturbation steps (buckling, modal analyses) work differently but that shouldn’t be a problem here.