public static void TestMembrane()
{
//small testing main diagonal of membrane local stiffness matrix
//there should not be zny zero on main diagonal of either local or global stiffness matrix,
//otherwise we get not positive definite exception error
var elm = new QuadrilaturalElement();
var arr = new[]
{
new Node(1, 1, 0),
new Node(4, 1, 0),
new Node(4, 4, 0),
new Node(1, 4, 0),
};
arr.CopyTo(elm.Nodes, 0);
var dkq = new Q4MembraneHelper();
elm.Material = new UniformIsotropicMaterial(2100, 0.3);
elm.Section = new UniformParametric2DSection(0.2);
var k = dkq.CalcLocalStiffnessMatrix(elm);
var n = k.RowCount;
for (var i = 0; i < n; i++)
{
if (k[i, i] <= 0)
{
Console.WriteLine("non positive entry on diagonal of Q4MembraneHelper stiffness");
}
}
}
public void Q4Membrane_GetBMatrix()
{
var elm = new QuadrilaturalElement();
elm.Nodes[0] = new Node(0, 0, 0);
elm.Nodes[1] = new Node(1, 10, 0);
elm.Nodes[2] = new Node(11, 12, 0);
elm.Nodes[3] = new Node(9, 2, 0);
var hlp = new Q4MembraneHelper()
{
TargetElement = elm
};
var test = hlp.GetBMatrixAt(elm, 0.1, 0.2);
var exact = new Matrix(3, 8);
//todo: fill the exact
}