Submodel technique is a powerful tool that can be used in many cases for structural models.
Submodel (or Local model) is based on using the displacements from a Global model, and map these to a small part of the original model, acting as boundary conditions for this new model.
The advantages of this approach are:
- after running the global model (with a coarse mesh), one can find out where the structure is more stressed, and then run only that region again with a finer mesh for a better representation;
- using submodel you can reuse a previous result (H3D file) and it is not necessary to re-run the whole model;
- multiple loadcases are supported;
- this can be used for later fatigue assessment, having a better representation on welds or other more detailed connections, that usually are not detailed in the global model;
The attached PDF file shows what are the steps for running a global-local model.
Also an example model is attached in the .zip file.
It used basically 3 main cards:
ASSIGN >> to load the initial global model H3D file
IMPORT(SUB = X) >> import the subcases from global to local
SPC (M) >> special SPC card to map the displacements (and optionally rotations) from the global model to the new local model.
An example with a 3 point bending plate.
Running first the global model (left), with the whole model, and then, later on, using the global H3D file as an input for the Local analysis (right).
