FEM: constants, add new module

src/Mod/Fem/CMakeLists.txt

@@ -221,6 +221,7 @@ SET(FemTools_SRCS
     femtools/__init__.py
     femtools/membertools.py
     femtools/ccxtools.py
+    femtools/constants.py
     femtools/errors.py
     femtools/femutils.py
     femtools/tokrules.py

src/Mod/Fem/femtools/constants.py

@@ -0,0 +1,56 @@
+# ***************************************************************************
+# *   Copyright (c) 2020 Bernd Hahnebach <bernd@bimstatik.org>              *
+# *                                                                         *
+# *   This program is free software; you can redistribute it and/or modify  *
+# *   it under the terms of the GNU Lesser General Public License (LGPL)    *
+# *   as published by the Free Software Foundation; either version 2 of     *
+# *   the License, or (at your option) any later version.                   *
+# *   for detail see the LICENCE text file.                                 *
+# *                                                                         *
+# *   This program 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 Library General Public License for more details.                  *
+# *                                                                         *
+# *   You should have received a copy of the GNU Library General Public     *
+# *   License along with this program; if not, write to the Free Software   *
+# *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  *
+# *   USA                                                                   *
+# *                                                                         *
+# ***************************************************************************
+""" Collection of natural constants for the Fem module.
+
+This module contains natural constants for the Fem module.
+All constants are in SI units.
+"""
+
+
+__title__ = "Constants"
+__author__ = "Bernd Hahnebach"
+__url__ = "http://www.freecadweb.org"
+
+
+def gravity():
+    return "9.82 m/s^2"
+
+
+def stefan_boltzmann():
+    return "5.67e-8 W/(m^2*K^4)"
+
+
+def permittivity_of_vakuum():
+    return "8.8542e-12 s^4*A^2/(m*kg)"
+
+
+def boltzmann_constant():
+    return "1.3807e-23 J/K"
+
+
+"""
+from FreeCAD import Units
+from femtools import constants
+Units.Quantity(constants.gravity()).getValueAs("mm/s^2")
+
+"""
+
+# TODO: a unit test to be sure these values are returned!