/// <inheritdoc />
public override Matrix GetGlobalStifnessMatrix()
{
//step 1 : get points in local system
//step 2 : get local stiffness matrix
//step 3 : expand local stiffness matrix
//step 4 : get global stiffness matrix
//step 1
var ls = GetLocalPoints();
var xs = new [] { ls[0].X, ls[1].X, ls[2].X };
var ys = new [] { ls[0].Y, ls[1].Y, ls[2].Y };
//step 2
var kl = CstElement.GetStiffnessMatrix(xs, ys, this._thickness, this.ElasticModulus, this.PoissonRatio,
this._formulationType);
//step 3
var currentOrder = new []
{
new FluentElementPermuteManager.ElementLocalDof(0, DoF.Dx),
new FluentElementPermuteManager.ElementLocalDof(0, DoF.Dy),
new FluentElementPermuteManager.ElementLocalDof(1, DoF.Dx),
new FluentElementPermuteManager.ElementLocalDof(1, DoF.Dy),
new FluentElementPermuteManager.ElementLocalDof(2, DoF.Dx),
new FluentElementPermuteManager.ElementLocalDof(2, DoF.Dy),
};
var kle = FluentElementPermuteManager.FullyExpand(kl, currentOrder, 3);
var lambda = GetTransformationMatrix();
var tr = Matrix.DiagonallyRepeat(lambda.Transpose(), 6); // eq. 5-16 page 78 (87 of file)
//step 4 : get global stiffness matrix
var buf = tr.Transpose() * kle * tr; //eq. 5-15 p77
return(buf);
}
private Matrix GetLocalMembraneStiffnessMatrix()
{
//cst
//step 1 : get points in local system
//step 2 : get local stiffness matrix
//step 3 : expand local stiffness matrix
//step 4 : get global stiffness matrix
//step 1
var ls = GetLocalPoints();
var xs = new[] { ls[0].X, ls[1].X, ls[2].X };
var ys = new[] { ls[0].Y, ls[1].Y, ls[2].Y };
//step 2
var kl = CstElement.GetStiffnessMatrix(xs, ys, this._thickness, this.ElasticModulus, this.PoissonRatio,
this._formulationType);
//step 3
var currentOrder = new[]
{
new ElementPermuteHelper.ElementLocalDof(0, DoF.Dx),
new ElementPermuteHelper.ElementLocalDof(0, DoF.Dy),
new ElementPermuteHelper.ElementLocalDof(1, DoF.Dx),
new ElementPermuteHelper.ElementLocalDof(1, DoF.Dy),
new ElementPermuteHelper.ElementLocalDof(2, DoF.Dx),
new ElementPermuteHelper.ElementLocalDof(2, DoF.Dy),
};
var kle = ElementPermuteHelper.FullyExpand(kl, currentOrder, 3);
return(kle);
}