FEM: Add support for amplitudes with CalculiX (#22851)

src/Mod/Fem/femsolver/calculix/write_amplitude.py

@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: LGPL-2.1-or-later
+
+# ***************************************************************************
+# *   Copyright (c) 2025 Jakub Michalski <jakub.j.michalski[at]gmail.com>         *
+# *                                                                         *
+# *   This file is part of FreeCAD.                                         *
+# *                                                                         *
+# *   FreeCAD is free software: you can redistribute it and/or modify it    *
+# *   under the terms of the GNU Lesser General Public License as           *
+# *   published by the Free Software Foundation, either version 2.1 of the  *
+# *   License, or (at your option) any later version.                       *
+# *                                                                         *
+# *   FreeCAD is distributed in the hope that it will be useful, but        *
+# *   WITHOUT ANY WARRANTY; without even the implied warranty of            *
+# *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU      *
+# *   Lesser General Public License for more details.                       *
+# *                                                                         *
+# *   You should have received a copy of the GNU Lesser General Public      *
+# *   License along with FreeCAD. If not, see                               *
+# *   <https://www.gnu.org/licenses/>.                                      *
+# *                                                                         *
+# ***************************************************************************
+
+__title__ = "FreeCAD FEM calculix amplitude"
+__author__ = "Jakub Michalski"
+__url__ = "https://www.freecad.org"
+
+
+def write_amplitude(f, ccxwriter):
+
+    # write amplitude definitions for all analysis features that use them
+
+    def write_obj_amplitude(obj):
+        if obj.EnableAmplitude:
+            f.write(f"*AMPLITUDE, NAME={obj.Name}\n")
+            for value in obj.AmplitudeValues:
+                f.write(f"{value}\n")
+            f.write("\n")
+
+    constraint_lists = [
+        ccxwriter.member.cons_force,
+        ccxwriter.member.cons_pressure,
+        ccxwriter.member.cons_displacement,
+        ccxwriter.member.cons_heatflux,
+        ccxwriter.member.cons_temperature,
+        ccxwriter.member.cons_bodyheatsource,
+    ]
+
+    for constraint_list in constraint_lists:
+        for entry in constraint_list:
+            write_obj_amplitude(entry["Object"])

src/Mod/Fem/femsolver/calculix/write_constraint_bodyheatsource.py

@@ -96,6 +96,9 @@ def write_constraint(f, femobj, bodyheatsource_obj, ccxwriter):
         volume = ref_feat.getSubObject(ref_sub_obj).Volume
         heat = bodyheatsource_obj.TotalPower / FreeCAD.Units.Quantity(volume, "mm^3")
     # write to file
-    f.write("*DFLUX\n")
+    if bodyheatsource_obj.EnableAmplitude:
+        f.write(f"*DFLUX, AMPLITUDE={bodyheatsource_obj.Name}\n")
+    else:
+        f.write("*DFLUX\n")
     f.write("{},BF,{:.13G}\n".format(bodyheatsource_obj.Name, heat.getValueAs("t/(mm*s^3)").Value))
     f.write("\n")

src/Mod/Fem/femsolver/calculix/write_constraint_displacement.py

@@ -66,7 +66,10 @@ def write_constraint(f, femobj, disp_obj, ccxwriter):
 
     # floats read from ccx should use {:.13G}, see comment in writer module
 
-    f.write("*BOUNDARY\n")
+    if disp_obj.EnableAmplitude:
+        f.write(f"*BOUNDARY, AMPLITUDE={disp_obj.Name}\n")
+    else:
+        f.write("*BOUNDARY\n")
     if not disp_obj.xFree:
         f.write(
             "{},1,1,{}\n".format(

src/Mod/Fem/femsolver/calculix/write_constraint_force.py

@@ -35,7 +35,7 @@ def get_sets_name():
 
 
 def get_before_write_meshdata_constraint():
-    return "*CLOAD\n"
+    return ""
 
 
 def get_after_write_meshdata_constraint():
@@ -46,6 +46,10 @@ def write_meshdata_constraint(f, femobj, force_obj, ccxwriter):
 
     # floats read from ccx should use {:.13G}, see comment in writer module
 
+    if force_obj.EnableAmplitude:
+        f.write(f"*CLOAD, AMPLITUDE={force_obj.Name}\n")
+    else:
+        f.write("*CLOAD\n")
     direction_vec = femobj["Object"].DirectionVector
     dir_zero_tol = 1e-15  # TODO: should this be more generally for more values?
     # be careful with raising the tolerance, a big load would have an impact

src/Mod/Fem/femsolver/calculix/write_constraint_heatflux.py

@@ -76,7 +76,12 @@ def write_meshdata_constraint(f, femobj, heatflux_obj, ccxwriter):
     else:
         return
 
-    f.write(f"*{heatflux_key_word}\n")
+    if heatflux_obj.EnableAmplitude:
+        heatflux_amplitude = f", AMPLITUDE={heatflux_obj.Name}"
+    else:
+        heatflux_amplitude = ""
+
+    f.write(f"*{heatflux_key_word}{heatflux_amplitude}\n")
     for ref_shape in femobj["HeatFluxFaceTable"]:
         elem_string = ref_shape[0]
         face_table = ref_shape[1]

src/Mod/Fem/femsolver/calculix/write_constraint_pressure.py

@@ -48,12 +48,14 @@ def write_meshdata_constraint(f, femobj, prs_obj, ccxwriter):
 
     # floats read from ccx should use {:.13G}, see comment in writer module
 
+    if prs_obj.EnableAmplitude:
+        f.write(f"*DLOAD, AMPLITUDE={prs_obj.Name}\n")
+    else:
+        f.write("*DLOAD\n")
     rev = -1 if prs_obj.Reversed else 1
     # the pressure has to be output in MPa
     pressure_quantity = FreeCAD.Units.Quantity(prs_obj.Pressure.getValueAs("MPa"))
     press_rev = rev * pressure_quantity
-
-    f.write("*DLOAD\n")
     for ref_shape in femobj["PressureFaces"]:
         # the loop is needed for compatibility reason
         # in deprecated method get_pressure_obj_faces_depreciated

src/Mod/Fem/femsolver/calculix/write_constraint_temperature.py

@@ -68,8 +68,12 @@ def write_constraint(f, femobj, temp_obj, ccxwriter):
     # floats read from ccx should use {:.13G}, see comment in writer module
 
     NumberOfNodes = len(femobj["Nodes"])
+    if temp_obj.EnableAmplitude:
+        temp_amplitude = f", AMPLITUDE={temp_obj.Name}"
+    else:
+        temp_amplitude = ""
     if temp_obj.ConstraintType == "Temperature":
-        f.write("*BOUNDARY\n")
+        f.write(f"*BOUNDARY{temp_amplitude}\n")
         f.write(
             "{},11,11,{}\n".format(
                 temp_obj.Name, FreeCAD.Units.Quantity(temp_obj.Temperature.getValueAs("K"))
@@ -77,7 +81,7 @@ def write_constraint(f, femobj, temp_obj, ccxwriter):
         )
         f.write("\n")
     elif temp_obj.ConstraintType == "CFlux":
-        f.write("*CFLUX\n")
+        f.write(f"*CFLUX{temp_amplitude}\n")
         # CFLUX has to be specified in mW
         f.write(
             "{},11,{}\n".format(

src/Mod/Fem/femsolver/calculix/writer.py

@@ -60,6 +60,7 @@ from . import write_femelement_material
 from . import write_femelement_matgeosets
 from . import write_footer
 from . import write_mesh
+from . import write_amplitude
 from . import write_step_equation
 from . import write_step_output
 from .. import writerbase
@@ -182,6 +183,9 @@ class FemInputWriterCcx(writerbase.FemInputWriter):
         self.write_constraints_propdata(inpfile, self.member.cons_transform, con_transform)
         self.write_constraints_propdata(inpfile, self.member.cons_rigidbody, con_rigidbody)
 
+        # amplitudes
+        write_amplitude.write_amplitude(inpfile, self)
+
         # step equation
         write_step_equation.write_step_equation(inpfile, self)