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This section gives a summary of FE mesh declaration with pointers to more detailed documentation.
Hand declaration of a model can only be done for small models and later sections address more realistic problems. This example mostly illustrates the form of the model data structure.
Figure 4.1: FE model.
The geometry is declared in the model.Node matrix (see section 7.1 and section 7.1.1). In this case, one defines 6 nodes for the truss and an arbitrary reference node to distinguish principal bending axes (see beam1)
% NodeID unused x y z model.Node=[ 1 0 0 0 0 1 0; ... 2 0 0 0 0 0 0; ... 3 0 0 0 1 1 0; ... 4 0 0 0 1 0 0; ... 5 0 0 0 2 0 0; ... 6 0 0 0 2 1 0; ... 7 0 0 0 1 1 1]; % reference node
The model description matrix (see section 7.1) describes 4 longerons, 2 diagonals and 2 battens. These can be declared using three groups of beam1 elements
model.Elt=[ ... % declaration of element group for longerons Inf abs('beam1') ; ... %node1 node2 MatID ProID nodeR, zeros to fill the matrix 1 3 1 1 7 0 ; ... 3 6 1 1 7 0 ; ... 2 4 1 1 7 0 ; ... 4 5 1 1 7 0 ; ... % declaration of element group for diagonals Inf abs('beam1') ; ... 2 3 1 2 7 0 ; ... 4 6 1 2 7 0 ; ... % declaration of element group for battens Inf abs('beam1') ; ... 3 4 1 3 7 0 ; ... 5 6 1 3 7 0 ];
You may view the declared geometry
cf=feplot; cf.model=model; % create feplot axes fecom(';view2;textnode;triax;'); % manipulate axes
The demo_fe script illustrates uses of this model.
