src/Mod/Fem/femsolver/elmer/equations/deformation_writer.py

# ***************************************************************************
# *   Copyright (c) 2023 Uwe Stöhr <uwestoehr@lyx.org>                      *
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# *   This file is part of the FreeCAD CAx development system.              *
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__title__ = "FreeCAD FEM Elasticity Elmer writer"
__author__ = "Uwe Stöhr"
__url__ = "https://www.freecad.org"

## \addtogroup FEM
#  @{

from FreeCAD import Console
from FreeCAD import Units

from .. import sifio
from .. import writer as general_writer
from femtools import femutils


class DeformationWriter:

    def __init__(self, writer, solver):
        self.write = writer
        self.solver = solver

    def getDeformationSolver(self, equation):
        s = self.write.createLinearSolver(equation)
        # output the equation parameters
        s = self.write.createNonlinearSolver(equation)
        s["Equation"] = "Nonlinear elasticity solver"
        s["Procedure"] = sifio.FileAttr("ElasticSolve/ElasticSolver")
        if equation.CalculateStrains is True:
            s["Calculate Strains"] = equation.CalculateStrains
        if equation.CalculateStresses is True:
            s["Calculate Stresses"] = equation.CalculateStresses
        if equation.CalculatePrincipal is True:
            s["Calculate Principal"] = equation.CalculatePrincipal
        if equation.CalculatePangle is True:
            s["Calculate Pangle"] = equation.CalculatePangle
        if equation.InitializeStateVariables is True:
            s["Initialize State Variables"] = equation.InitializeStateVariables
        if equation.MixedFormulation is True:
            s["Mixed Formulation"] = equation.MixedFormulation
        if equation.NeoHookeanMaterial is True:
            s["Neo-Hookean Material"] = equation.NeoHookeanMaterial
        s["Exec Solver"] = "Always"
        s["Optimize Bandwidth"] = True
        s["Stabilize"] = equation.Stabilize
        s["Variable"] = equation.Variable
        return s

    def handleDeformationEquation(self, bodies, equation):
        for b in bodies:
            # not for bodies with fluid material
            if not self.write.isBodyMaterialFluid(b):
                if equation.PlaneStress:
                    self.write.equation(b, "Plane Stress", equation.PlaneStress)

    def handleDeformationConstants(self):
        pass

    def handleDeformationBndConditions(self):
        for obj in self.write.getMember("Fem::ConstraintPressure"):
            if obj.References:
                for name in obj.References[0][1]:
                    pressure = float(obj.Pressure.getValueAs("Pa"))
                    if not obj.Reversed:
                        pressure *= -1
                    self.write.boundary(name, "Normal Force", pressure)
                self.write.handled(obj)
        for obj in self.write.getMember("Fem::ConstraintFixed"):
            if obj.References:
                for name in obj.References[0][1]:
                    self.write.boundary(name, "Displacement 1", 0.0)
                    self.write.boundary(name, "Displacement 2", 0.0)
                    self.write.boundary(name, "Displacement 3", 0.0)
                self.write.handled(obj)
        for obj in self.write.getMember("Fem::ConstraintForce"):
            if obj.References:
                for name in obj.References[0][1]:
                    force = float(obj.Force.getValueAs("N"))
                    self.write.boundary(name, "Force 1", obj.DirectionVector.x * force)
                    self.write.boundary(name, "Force 2", obj.DirectionVector.y * force)
                    self.write.boundary(name, "Force 3", obj.DirectionVector.z * force)
                    self.write.boundary(name, "Force 1 Normalize by Area", True)
                    self.write.boundary(name, "Force 2 Normalize by Area", True)
                    self.write.boundary(name, "Force 3 Normalize by Area", True)
                self.write.handled(obj)
        for obj in self.write.getMember("Fem::ConstraintDisplacement"):
            if obj.References:
                for name in obj.References[0][1]:
                    if obj.useFlowSurfaceForce:
                        self.write.boundary(name, "FSI BC", obj.useFlowSurfaceForce)
                        # if useFlowSurfaceForce no displacements must be output
                        continue
                    if not obj.xFree:
                        if not obj.hasXFormula:
                            displacement = float(obj.xDisplacement.getValueAs("m"))
                        else:
                            displacement = obj.xDisplacementFormula
                        self.write.boundary(name, "Displacement 1", displacement)
                    if not obj.yFree:
                        if not obj.hasYFormula:
                            displacement = float(obj.yDisplacement.getValueAs("m"))
                        else:
                            displacement = obj.yDisplacementFormula
                        self.write.boundary(name, "Displacement 2", displacement)
                    if not obj.zFree:
                        if not obj.hasZFormula:
                            displacement = float(obj.zDisplacement.getValueAs("m"))
                        else:
                            displacement = obj.zDisplacementFormula
                        self.write.boundary(name, "Displacement 3", displacement)
                self.write.handled(obj)
        for obj in self.write.getMember("Fem::ConstraintSpring"):
            if obj.References:
                for name in obj.References[0][1]:
                    if obj.ElmerStiffness == "Normal Stiffness":
                        spring = float(obj.NormalStiffness.getValueAs("N/m"))
                    else:
                        spring = float(obj.TangentialStiffness.getValueAs("N/m"))
                    self.write.boundary(name, "Spring", spring)
                self.write.handled(obj)

    def handleDeformationInitial(self, bodies):
        pass

    def handleDeformationBodyForces(self, bodies):
        obj = self.write.getSingleMember("Fem::ConstraintSelfWeight")
        if obj is not None:
            for name in bodies:
                gravity = self.write.convert(obj.GravityAcceleration.toStr(), "L/T^2")
                if self.write.getBodyMaterial(name) is None:
                    raise general_writer.WriteError(
                        f"The body {name} is not referenced in any material.\n\n"
                    )
                m = self.write.getBodyMaterial(name).Material

                densityQuantity = Units.Quantity(m["Density"])
                dimension = "M/L^3"
                if name.startswith("Edge"):
                    # not tested, bernd
                    # TODO: test
                    densityQuantity.Unit = Units.Unit(-2, 1)
                    dimension = "M/L^2"
                density = self.write.convert(densityQuantity, dimension)

                force1 = gravity * obj.GravityDirection.x * density
                force2 = gravity * obj.GravityDirection.y * density
                force3 = gravity * obj.GravityDirection.z * density
                self.write.bodyForce(name, "Stress Bodyforce 1", force1)
                self.write.bodyForce(name, "Stress Bodyforce 2", force2)
                self.write.bodyForce(name, "Stress Bodyforce 3", force3)
            self.write.handled(obj)

    def handleDeformationMaterial(self, bodies):
        # density
        # is needed for self weight constraints and frequency analysis
        density_needed = False
        for equation in self.solver.Group:
            if femutils.is_of_type(equation, "Fem::EquationElmerElasticity"):
                if equation.EigenAnalysis is True:
                    density_needed = True
                    break  # there could be a second equation without frequency
        gravObj = self.write.getSingleMember("Fem::ConstraintSelfWeight")
        if gravObj is not None:
            density_needed = True
        # temperature
        tempObj = self.write.getSingleMember("Fem::ConstraintInitialTemperature")
        if tempObj is not None:
            refTemp = float(tempObj.initialTemperature.getValueAs("K"))
            for name in bodies:
                self.write.material(name, "Reference Temperature", refTemp)
        # get the material data for all bodies
        for obj in self.write.getMember("App::MaterialObject"):
            m = obj.Material
            refs = obj.References[0][1] if obj.References else self.write.getAllBodies()
            for name in (n for n in refs if n in bodies):
                # don't evaluate fluid material
                if self.write.isBodyMaterialFluid(name):
                    break
                if "YoungsModulus" not in m:
                    Console.PrintMessage(f"m: {m}\n")
                    # it is no fluid but also no solid
                    # -> user set no material reference at all
                    # that now material is known
                    raise general_writer.WriteError(
                        "There are two or more materials with empty references.\n\n"
                        "Set for the materials to what solid they belong to.\n"
                    )
                self.write.material(name, "Name", m["Name"])
                if density_needed is True:
                    self.write.material(name, "Density", self.write.getDensity(m))
                self.write.material(name, "Youngs Modulus", self._getYoungsModulus(m))
                self.write.material(name, "Poisson ratio", float(m["PoissonRatio"]))
                if tempObj:
                    self.write.material(
                        name,
                        "Heat expansion Coefficient",
                        self.write.convert(m["ThermalExpansionCoefficient"], "O^-1"),
                    )

    def _getYoungsModulus(self, m):
        youngsModulus = self.write.convert(m["YoungsModulus"], "M/(L*T^2)")
        if self.write.getMeshDimension() == 2:
            youngsModulus *= 1e3
        return youngsModulus


##  @}