![]() ![]() ![]() The OCS is the default frame of reference when starting a part, assembly, etc., so its location is dependent on how a model is built. One way of interpreting the matrix notation is this: If an object is rotating about the X-axis then Lxx is its inertia around the X-axis while simultaneously Lxz is its inertia around the Z-axis.įinally, you’ve probably noticed that Mass Properties also give MOI values about the Output Coordinate System axes. This is because the object’s mass is balanced along this axis in front and back of the plane of symmetry. Here we see zero values for all cross-products containing the Z-axis (no wobble in Z-direction). Let’s look at an example of an object that is symmetrical about only one plane (XY): In our example model above, we would expect its cross-product values to be zero for rotation about the COM axes and non-zero about any different axes. Think of a car wheel being balanced to prevent wobble. ![]() If it is non-zero, then we can expect an off-axis torque or acceleration that will result in a wobble of the object not a pure rotation. Cross-Product MOI is really just an indication of the symmetry of the object. Any non-diagonal element represents a Cross-Product Moment of Inertia. Without getting too technical, the diagonal elements of theses matrices always represent Moments of Inertia about the primary axes of an established coordinate system. The groups of numbers (3X3 matrices) at the bottom of the Mass Properties window represent Inertia Tensors. If it is rotated about any one of these axes, we will see Principal Moment of Inertia values which are displayed in units of ML 2: It all goes back to Moments of Inertia which depend on an object’s mass, shape, and axis of rotation.Įvery object has a Center of Mass that, if suspended in midair from this point, will be perfectly balanced. Taking the following symmetrical object as an example, we can see the principal axes through its center of mass. But how in blazes does someone interpret the rest of the information included in Mass Properties, particularly the numbers at the bottom? What exactly are they telling us? We have all referred to Mass Properties when working with solid models, especially when taking SOLIDWORKS certifications! For the most part, very useful information is available at a glance i.e., Density, Mass, Volume, Surface Area, etc. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |