public double[,] CreateMassMatrix()
{
double[,] tempM = MatrixOperations.CreateDiagonalMatrix(6, 1.0);
double[] xUpdated = UpdateNodalCoordinates(DisplacementVector);
double a = Math.Pow(Math.Pow(xUpdated[0] - xUpdated[2], 2) + Math.Pow(xUpdated[1] - xUpdated[3], 2), 0.5);
double b = Math.Pow(Math.Pow(xUpdated[0] - xUpdated[4], 2) + Math.Pow(xUpdated[1] - xUpdated[5], 2), 0.5);
double c = Math.Pow(Math.Pow(xUpdated[2] - xUpdated[4], 2) + Math.Pow(xUpdated[3] - xUpdated[5], 2), 0.5);
double t = (a + b + c) / 2;
double area = Math.Pow(t * (t - a) * (t - b) * (t - c), 0.5);
double scalar = Properties.Density * Properties.Thickness * area / 3.0;
double[,] M = MatrixOperations.ScalarMatrixProductNew(scalar, tempM);
double waveSpeed = Math.Sqrt(Properties.YoungMod / Properties.Density);
return(M);
}
public double[,] CreateMassMatrix()
{
//double[,] M = new double[8, 8];
double[,] tempM = MatrixOperations.CreateDiagonalMatrix(8, 1.0);
double length = 0.3;
double scalar = Properties.Density * Properties.Thickness * length * (length / 3.0) / 4.0;
double[,] M = MatrixOperations.ScalarMatrixProductNew(scalar, tempM);
double waveSpeed = Math.Sqrt(Properties.YoungMod / Properties.Density);
double deltatCritical = length * Math.Sqrt(1.0 - 0.33) / waveSpeed;
//--------------------------------------------------------------
//for (int i = 0; i < 2; i++)
//{
// for (int j = 0; j < 2; j++)
// {
// double[] gP = GaussPoints(i, j).Item1;
// double[] gW = GaussPoints(i, j).Item2;
// Dictionary<string, double[]> localdN = CalculateShapeFunctionsLocalDerivatives(gP);
// double[,] J = CalculateJacobian(localdN);
// double[,] invJ = CalculateInverseJacobian(J).Item1;
// double detJ = CalculateInverseJacobian(J).Item2;
// double[,] Nmatrix = CalculateShapeFunctionMatrix(gP[i], gP[j]);
// M = MatrixOperations.MatrixAddition(M, MatrixOperations.ScalarMatrixProductNew(Properties.Density * Properties.Thickness * detJ * gW[i] * gW[j],
// MatrixOperations.MatrixProduct(MatrixOperations.Transpose(Nmatrix), Nmatrix)));
// }
//}
//--------------------------------------------------------
//for (int i = 0; i < 8; i++)
//{
// M[i, i] = 4.0;
//}
//for (int i = 0; i < 6; i++)
//{
// M[i, i + 2] = 2.0;
// M[i + 2, i] = 2.0;
//}
//for (int i = 0; i < 4; i++)
//{
// M[i, i + 4] = 1.0;
// M[i + 4, i] = 1.0;
//}
//for (int i = 0; i < 2; i++)
//{
// M[i, i + 6] = 2.0;
// M[i + 6, i] = 2.0;
//}
//M = MatrixOperations.ScalarMatrixProductNew(0.67 * 0.8 * Properties.Density * Properties.Thickness / 32, M);
//MatrixOperations.PrintMatrix(M);
return(M);
}