FEM: fix, transient material was used in some cases even if material …

…was not changed

src/Mod/Fem/TaskPanelMechanicalMaterial.ui

@@ -176,7 +176,7 @@
            <double>0.100000000000000</double>
           </property>
           <property name="value">
-           <double>0.300000000000000</double>
+           <double>0.000000000000000</double>
           </property>
          </widget>
         </item>
@@ -202,7 +202,7 @@
            </size>
           </property>
           <property name="text">
-           <string>0 kg/m^3</string>
+           <string/>
           </property>
           <property name="alignment">
            <set>Qt::AlignRight|Qt::AlignTrailing|Qt::AlignVCenter</set>
@@ -214,7 +214,7 @@
            <double>2000000000.000000000000000</double>
           </property>
           <property name="unit" stdset="0">
-           <string notr="true">kg/m^3</string>
+           <string notr="true">kg/mm^3</string>
           </property>
           <property name="decimals" stdset="0">
            <number>3</number>

src/Mod/Fem/_TaskPanelMechanicalMaterial.py

@@ -113,28 +113,38 @@ def goMatWeb(self):
 
     def ym_changed(self, value):
         import Units
+        # FreeCADs standard unit for stress is kPa
         old_ym = Units.Quantity(self.material['YoungsModulus'])
-        if old_ym != value:
-            material = self.material
-            # FreeCAD uses kPa internall for Stress
-            material['YoungsModulus'] = unicode(value) + " kPa"
-            self.material = material
+        variation = 0.001
+        if value:
+            if not (1 - variation < float(old_ym) / value < 1 + variation):
+                # YoungsModulus has changed
+                material = self.material
+                material['YoungsModulus'] = unicode(value) + " kPa"
+                self.material = material
 
     def density_changed(self, value):
         import Units
+        # FreeCADs standard unit for density is kg/mm^3
         old_density = Units.Quantity(self.material['Density'])
-        if old_density != value:
-            material = self.material
-            material['Density'] = unicode(value) + " kg/mm^3"
-            self.material = material
+        variation = 0.001
+        if value:
+            if not (1 - variation < float(old_density) / value < 1 + variation):
+                # density has changed
+                material = self.material
+                material['Density'] = unicode(value) + " kg/mm^3"
+                self.material = material
 
     def pr_changed(self, value):
         import Units
         old_pr = Units.Quantity(self.material['PoissonRatio'])
-        if old_pr != value:
-            material = self.material
-            material['PoissonRatio'] = unicode(value)
-            self.material = material
+        variation = 0.001
+        if value:
+            if  not (1 - variation < float(old_pr) / value < 1 + variation):
+                # PoissonRatio has changed
+                material = self.material
+                material['PoissonRatio'] = unicode(value)
+                self.material = material
 
     def choose_material(self, index):
         if index < 0: