The Elastic Predeformation node can be used for incremental solution updates using the deformed geometry functionality. This approach can significantly speed up computations is case of large elastic deformations.
The Elastic Predeformation subnode is only available with some COMSOL products (see
https://www.comsol.com/products/specifications/). It is available for 3D, 2D, and 2D axisymmetry.
By default, the Predeformation gradient is set to
From material frame, which means that the deformation gradient relating the geometry and material frames will be used. The predeformation gradient will enter into the definition of the elastic strains, which will create an initial stress state on the material frame corresponding to the total deformation starting from the original geometry configuration.
When the check box Store deformation history is checked (default) the displacement field computed during the current solution step (using the current material frame) will be stored in a special variable,
u_pd, which can be used then on the next solution step, if any. When the check box
Set up deformed geometry is selected (default) the material frame will differ from the geometry frame by a prescribed displacement
u_pd computed at the previous solution step. The solution computed on each step represents an incremental step in the total deformation. The total solution can be set up using either a time-dependent or a stationary parametric study, for example, with the loading gradually increasing from one step to the other. Special postprocessing variables,
u_tot_old and
u_tot, are defined to store the total displacement before and after each step, respectively.
Alternatively, you can set the Predeformation gradient to
User defined. Then, you can enter explicitly expressions referring to some previously computed solution, for example:
withsol('sol1', solid.FdxX), and so on. The contribution will enter the elastic strain definitions, which will result into an initial stress state corresponding to the previously computed solution.
