Changeset 1118

Timestamp:

05/04/08 21:39:16 (2 months ago)

Author:

otter

Message:

Enhanced efficiency of friction models of Rotational and Translational library in some situations (only of peak > 1)

Location:

branches/maintenance/2.2.2/Modelica

Files:

• Mechanics/Rotational.mo (modified) (4 diffs)
• Mechanics/Translational.mo (modified) (5 diffs)
• package.mo (modified) (1 diff)

branches/maintenance/2.2.2/Modelica/Mechanics/Rotational.mo

@@ -724 +724 @@
       Modelica.Mechanics.Rotational.Torque torque 
                                annotation (extent=[-65, -5; -55, 5]);
-      Modelica.Mechanics.Rotational.Clutch clutch1(peak=1.1, fn_max=20) 
+      Modelica.Mechanics.Rotational.Clutch clutch1(          fn_max=20, peak=1.1)
         annotation (extent=[-25, -5; -15, 5]);
       Modelica.Blocks.Sources.Sine sin1(amplitude=10, freqHz=5) 
@@ -732 +732 @@
       Modelica.Mechanics.Rotational.Inertia J2(J=1, initType=Modelica.Mechanics.Rotational.Types.Init.InitialState) 
                                  annotation (extent=[-5, -5; 5, 5]);
-      Modelica.Mechanics.Rotational.Clutch clutch2(peak=1.1, fn_max=20) 
+      Modelica.Mechanics.Rotational.Clutch clutch2(          fn_max=20, peak=1.1)
         annotation (extent=[15, -5; 25, 5]);
       Modelica.Mechanics.Rotational.Inertia J3(J=1, initType=Modelica.Mechanics.Rotational.Types.Init.InitialState) 
                                  annotation (extent=[35, -5; 45, 5]);
-      Modelica.Mechanics.Rotational.Clutch clutch3(peak=1.1, fn_max=20) 
+      Modelica.Mechanics.Rotational.Clutch clutch3(          fn_max=20, peak=1.1)
         annotation (extent=[55, -5; 65, 5]);
       Modelica.Mechanics.Rotational.Inertia J4(J=1, initType=Modelica.Mechanics.Rotational.Types.Init.InitialState) 
@@ -1817 +1817 @@
       constant SI.AngularAcceleration unitAngularAcceleration = 1;
       constant SI.Torque unitTorque = 1;
-      
+      Real sa0 = (tau0_max + (tau0_max - tau0))/unitTorque 
+        "Value of sa when start of forward sliding at w=0";
     equation 
       /* Friction characteristic
@@ -1824 +1825 @@
       special code shall be generated) */
       
-      startForward = pre(mode) == Stuck and (sa > tau0_max/unitTorque or pre(startForward)
-         and sa > tau0/unitTorque) or pre(mode) == Backward and w_relfric > w_small or 
-        initial() and (w_relfric > 0);
-      startBackward = pre(mode) == Stuck and (sa < -tau0_max/unitTorque or pre(
-        startBackward) and sa < -tau0/unitTorque) or pre(mode) == Forward and w_relfric <
-        -w_small or initial() and (w_relfric < 0);
-      locked = not free and not (pre(mode) == Forward or startForward or pre(
-        mode) == Backward or startBackward);
+      startForward = pre(mode) == Stuck and sa > tau0_max/unitTorque or 
+                     pre(mode) == Backward and w_relfric > w_small or 
+                     initial() and (w_relfric > 0);
+      startBackward = pre(mode) == Stuck and sa < -tau0_max/unitTorque or 
+                      pre(mode) == Forward and w_relfric < -w_small or 
+                      initial() and (w_relfric < 0);
+      locked = not free and not (pre(mode) == Forward or startForward or pre(mode) == Backward or startBackward);
       
       a_relfric = unitAngularAcceleration *
-              (if locked then 0 else if free then sa else if startForward then 
-              sa - tau0/unitTorque else if startBackward then sa + tau0/unitTorque else if pre(mode)
-         == Forward then sa - tau0/unitTorque else sa + tau0/unitTorque);
+              (if locked then 0 else if free then sa else 
+              if startForward then sa - sa0 else if startBackward then sa + sa0 else 
+              if pre(mode)== Forward then sa - sa0 else sa + sa0);
       
       /* Friction torque has to be defined in a subclass. Example for a clutch:

branches/maintenance/2.2.2/Modelica/Mechanics/Translational.mo

@@ -302 +302 @@
       Translational.Spring S1(
         s_rel0=1,
-        c=1e3, 
+        c=1e3,
         s_rel(start=1, fixed=false)) 
                         annotation (extent=[-58, -20; -38, 0]);
@@ -308 +308 @@
       Translational.SpringDamper SD1(
         s_rel0=1,
-        c=111, 
+        c=111,
         s_rel(start=1, fixed=true)) 
                         annotation (extent=[20, -20; 40, 0]);
@@ -1526 +1526 @@
 </ul>
 </html>"));
-      
+    protected 
       constant SI.Acceleration unitAcceleration = 1;
       constant SI.Force unitForce = 1;
+      Real sa0 = (f0_max + (f0_max - f0))/unitForce 
+        "Value of sa when start of forward sliding at w=0";
     equation 
       /* Friction characteristic
@@ -1536 +1538 @@
   */
       
-      startForward = pre(mode) == Stuck and (sa > f0_max/unitForce and s < (smax - L/2) or 
-            pre(startForward) and sa > f0/unitForce and s < (smax - L/2)) or pre(mode)
-         == Backward and v_relfric > v_small or initial() and (v_relfric > 0);
-      startBackward = pre(mode) == Stuck and (sa < -f0_max/unitForce and s > (smin + L/2) or 
-            pre(startBackward) and sa < -f0/unitForce and s > (smin + L/2)) or pre(mode)
-         == Forward and v_relfric < -v_small or initial() and (v_relfric < 0);
+      startForward = pre(mode) == Stuck and sa > f0_max/unitForce and s < (smax - L/2) or 
+                     pre(mode) == Backward and v_relfric > v_small or initial() and (v_relfric > 0);
+      startBackward = pre(mode) == Stuck and sa < -f0_max/unitForce and s > (smin + L/2) or 
+                      pre(mode) == Forward and v_relfric < -v_small or initial() and (v_relfric < 0);
       
       locked = not free and not (pre(mode) == Forward or startForward or pre(
@@ -1547 +1547 @@
       
       a_relfric = unitAcceleration*(if locked then 0 else if free then sa else if startForward then 
-              sa - f0/unitForce else if startBackward then sa + f0/unitForce else if pre(mode) ==
-        Forward then sa - f0/unitForce else sa + f0/unitForce);
+              sa - sa0 else if startBackward then sa + sa0 else if pre(mode) == Forward then sa - sa0 else sa + sa0);
       
       /* Friction torque has to be defined in a subclass. Example for a clutch:

branches/maintenance/2.2.2/Modelica/package.mo

@@ -649 +649 @@
                         to warnings.</td> 
   </tr>
+
+  <tr><td colspan=\"2\"><b>Mechanics.Rotational.Interfaces.</b></td></tr>
+  <tr><td valign=\"top\"> FrictionBase </td>
+      <td valign=\"top\"> Corrected and simplified parameterized curve description.
+                        The previous formulation could lead to an inconsistent mixed system
+                        of equations if peak > 1 and then an additional event iteration
+                        was needed to find the solution. The change therefore enhances
+                        efficiency in some situations. </td> 
+  </tr>
+  <tr><td colspan=\"2\"><b>Mechanics.Translational.Interfaces.</b></td></tr>
+  <tr><td valign=\"top\"> FrictionBase </td>
+      <td valign=\"top\"> Corrected and simplified parameterized curve description.
+                        The previous formulation could lead to an inconsistent mixed system
+                        of equations if peak > 1 and then an additional event iteration
+                        was needed to find the solution. The change therefore enhances
+                        efficiency in some situations. </td> 
+  </tr>
+
   <tr><td colspan=\"2\"><b>Media.Interfaces.PartialSimpleMedium</b></td></tr>
   <tr><td valign=\"top\"> pressure<br>