Moment of inertia measures how much a body can resist rotation about a particular axis. In mathematics, it is the summation of the product of the mass of each particle and its square distance from the centre of rotation.
Mathematics has formulas for regular shapes, and there are ways to derive the moment of inertia for complex shapes, like integration.
However, getting the moment of inertia on Solidworks is easier than using a formula, especially for complex shapes. It is straightforward for simple shapes like cylinders, cubes, etc. In this example, we will be using a sphere.
Step 1: Start a new sketch on the front plane in Solidworks and draw a semicircle of diameter 80mm in any orientation. Use the Centre point arc in the sketch tab (circled green). To fully define the semicircle, ensure it is centred at the origin.
Step 2: In the feature tab, select the revolve tool. It should automatically select the vertical line as the axis of revolution. If that is not the case, manually select the semicircle’s vertical line and set the revolution angle to 360 degrees to get a complete sphere.
Step 3: You can add specific materials to the sphere if required. Then go to the “Evaluate” tab and select “Mass properties”. A dialogue box shows a long list of the part’s properties, such as mass, the centre of gravity, density, volume, surface area, and moment of inertia (in the red rectangle).
Step 4: You can go further to print the mass properties if you wish to use the information elsewhere. Click the “Print” button (circled blue in the image above). You will be guided as to how to save the printed file. When you open the PDF file, it should look like the image below.