Result <LoadIncrementalState> GetCorrection(LoadState state, LoadIncrementalState prediction, StructureInfo info)
{
ILinearSolver stiffnessMatrix = info.Stiffness(state.Displacement);
Vector <double> dut = stiffnessMatrix.Solve(info.ReferenceLoad);
Vector <double> reaction = info.Reaction(state.Displacement);
Vector <double> equilibrium = info.InitialLoad + state.Lambda * info.ReferenceLoad - reaction;
Vector <double> dur = stiffnessMatrix.Solve(equilibrium);
Result <LoadIncrementalState> incrementalStateResult = Scheme.Correct(state, prediction, info, dut, dur);
return(incrementalStateResult);
}
IEnumerable <double> GetErrors(LoadState newState, LoadState oldState, StructureInfo info)
{
Vector <double> reaction = info.Reaction(newState.Displacement);
Vector <double> equilibrium = info.InitialLoad + newState.Lambda * info.ReferenceLoad - reaction;
Vector <double> incrementDisplacement = newState.Displacement - oldState.Displacement;
yield return(incrementDisplacement.Norm(2) / newState.Displacement.Norm(2));
yield return(equilibrium.Norm(2) / info.ReferenceLoad.Norm(2));
yield return(Math.Abs(newState.Displacement.DotProduct(equilibrium) / newState.Displacement.DotProduct(info.ReferenceLoad)));
}
public LoadIncrementalState SelectDisplacement(
StructureInfo info
, LoadState state
, LoadIncrementalState prediction
, IEnumerable <LoadIncrementalState> candidates)
{
double Function(LoadIncrementalState candidate)
{
Vector <double> displacement = state.Displacement + candidate.IncrementDisplacement;
Vector <double> reaction = info.Reaction(displacement);
double lambda = state.Lambda + candidate.IncrementLambda;
Vector <double> equilibriumVector = info.InitialLoad + lambda * info.ReferenceLoad - reaction;
return(equilibriumVector.Norm(2));
}
return(candidates.MinBy(Function).First());
}
internal LoadIncrementalState Predict(LoadState state, double initialStiffness, StructureInfo info)
{
Vector<double> equilibrium = info.InitialLoad + state.Lambda * info.ReferenceLoad - info.Reaction(state.Displacement);
ILinearSolver mK = info.Stiffness(state.Displacement);
Vector<double> Dvt = mK.Solve(info.ReferenceLoad);
Vector<double> Dvr = mK.Solve(equilibrium);
double bergam = GetBergamParameter(initialStiffness, Dvt, info);
double DLambda = Scheme.Predict(Dvt, info.ReferenceLoad) * Math.Sign(bergam);
Vector<double> Dv = DLambda * Dvt + Dvr;
return new LoadIncrementalState(DLambda, Dv);
}
