Motion for Layout Sketches

You can run Animation and Motion Analysis motion studies for layout sketch mechanisms you create from sketch blocks.

Motion Analysis studies require values for the mass, center of mass, and moments of inertia for each block in the layout sketch. Estimated values for mass and moments of inertia are assigned to each block, based on a uniform steel block. The default value for the center of mass is at the center of the block.

For each block in the layout sketch, you can modify the component mass properties by editing Mass Properties in the Block PropertyManager before running a Motion Analysis study.

You cannot edit the mass properties for a layout sketch motion study unless you select Motion Analysis for the motion study type.

Mass Moments of Inertia

For each part in an assembly, the mass moment of inertia matrix is used when you calculate Motion Analysis motion studies. This matrix plays the same role for rotary motion as that played by mass for linear motion.

The mass moments of inertia are the unique components of the symmetric mass moment of inertia matrix. Six mass moments of inertia values are required for this matrix: one each for the moments along the X, Y, and Z axes of the part coordinate frame, and three cross-component terms XY, YZ, and XZ. These values are automatically computed based on the geometry of the sketch block. If you have this data, you can modify the default values in the Mass Moments of Inertia dialog box.

To open this dialog box:

From a Motion Analysis motion study for a layout sketch, select Insert > Layout , select a block, and click Moments of Inertia for Mass Properties in the Block PropertyManager.

Mass Moments of Inertia

Modify the six mass inertia moments and cross moments:
  • Ixx
  • Iyy
  • Izz
  • Ixy
  • Iyz
  • Izx

Running Motion Studies for Layout Sketch Mechanisms

To run a motion study for a layout sketch:

  1. Create the layout sketch mechanism, editing Mass Properties in the Block PropertyManagers as necessary.
    Mass properties are used only for motion calculations in Motion Analysis studies.
  2. Create a motion study for the layout sketch.
    Constraints you apply in the layout sketch appear as mates in the motion study. You cannot edit these mates.
  3. Add motion study elements, such as forces or motors, as necessary.
    You cannot add contact between layout sketch blocks.
  4. Select either Motion Analysis or Animation and run the motion study.

Setting Mass Properties in Layout Sketch Blocks

With SOLIDWORKS Motion added in, you can modify the mass properties for each layout sketch block used in a Motion Analysis motion study.

To modify the mass properties for a layout sketch block:

  1. Open the layout sketch for an assembly and click Layout (Layout Tools toolbar).
  2. Select a layout sketch block entity.
    The Block PropertyManager appears with an estimated value for the block mass under Mass Properties.
  3. Modify the Mass as necessary.
  4. Click Move Center of Mass to display or move the estimated center of mass .
    You can click Reset Center of Mass to replace the mass in the center of the block.
  5. Click Moments of Inertia to modify the mass moments and products of inertia.
    The Moments of Inertia dialog box appears. Modify moments and click OK.
  6. Click .
    Sketch block mass properties are used only for two-dimensional motion of layout sketches. Three-dimensional parts made from blocks use the assembly Mass Properties.
  7. Click to close the layout sketch.