About System Measures
Several standard, predefined measures are provided that track the overall behavior of your mechanism. You can create all of the following System measures if you have a Mechanism Dynamics license. If you do not have a Mechanism Dynamics license, you can only create Degrees of freedom, Redundancies, or Time measures.
• Degrees of freedom—Measure the number of degrees of freedom (DOF) in your mechanism. In most cases, the degrees of freedom does not change during an analysis. An exception is if you are modeling cams with liftoff. In this case, the DOF changes when the cams separate, and you may want to graph the degrees of freedom.
 |
In previous releases, Degrees of freedom and Redundancies were listed as default measures when you opened the Measure Results dialog box. If you created your mechanism in a previous Mechanism Design release, these default Degrees of freedom and Redundancies measures appear in the list when you open your model in the current release, but you can now edit them or delete them from the list.
|
• Redundancies—Measure the number of redundancies your mechanism contains.
• Time—Measure the time at each step of the analysis.
• Kinetic energy—Measure the total kinetic energy for the mechanism. The kinetic energy is a scalar sum of the kinetic energy for each rigid body, relative to the ground body WCS.
• Linear momentum—Measure the total linear momentum of the mechanism. The linear momentum is the sum over all rigid bodies in the mechanism of the global velocity of each rigid body's center of mass multiplied by its mass.
• Angular momentum—Measure the total angular momentum of the mechanism. The angular momentum is the sum over all rigid bodies in the mechanism of the inertial angular momentum for each rigid body. For each rigid body, this is the product of the moment of inertia at the center of mass times the angular velocity of the rigid body. System angular momentum is reported relative to the ground body WCS.
• Total mass—Measure the sum of the masses for all rigid bodies, including the ground body, in your mechanism.
• Center of mass—Measure the distance to the center of mass of the mechanism relative to the ground body WCS.
• Total centroidal inertia—Measure the total centroidal inertia of the mechanism relative to the center of mass of the mechanism. Centroidal inertia is calculated by regarding all rigid bodies, including the ground body, in the mechanism as a single rigid body with the same mass distribution as the mechanism. Inertial properties of this single rigid body are then computed with respect to the mass center of this rigid body, which is the system mass center.