/// <summary>
///
/// </summary>
/// <returns></returns>
public override StiffnessMatrix LocalStiffnessMatrix()
{
KeyedSquareMatrix <Strain> materialMatrix = this.MaterialMatrix;
SharpFE.Maths.Integration.Gauss.GaussianIntegration2D gaussianIntegrator = new SharpFE.Maths.Integration.Gauss.GaussianIntegration2D(2);
Matrix <double> k = gaussianIntegrator.Integrate((gaussIntegrationPointi, gaussIntegrationPointj) => {
CartesianPoint pnt = new CartesianPoint(gaussIntegrationPointi, gaussIntegrationPointj, 0);
KeyedRowColumnMatrix <Strain, NodalDegreeOfFreedom> strainDisplacementMatrix = this.StrainDisplacementMatrix(pnt);
KeyedRowColumnMatrix <NodalDegreeOfFreedom, Strain> bte = strainDisplacementMatrix.TransposeThisAndMultiply <Strain>(materialMatrix);
KeyedRowColumnMatrix <NodalDegreeOfFreedom, NodalDegreeOfFreedom> bteb = bte.Multiply <Strain, NodalDegreeOfFreedom>(strainDisplacementMatrix);
double jacobianDeterminant = this.Jacobian(pnt).Determinant();
bteb = bteb.Multiply(jacobianDeterminant);
return((Matrix <double>)bteb);
});
double thickness = this.Element.Thickness; //TODO interpolate over element (i.e. allow varying thickness over element)
k = k.Multiply(thickness);
IList <NodalDegreeOfFreedom> supportedNodalDegreesOfFreedom = this.Element.SupportedLocalNodalDegreeOfFreedoms;
return(new StiffnessMatrix(supportedNodalDegreesOfFreedom, supportedNodalDegreesOfFreedom, k));
}
