About Screw Calculations (AutoCAD Mechanical Toolset)

The screw calculation feature is used to calculate stresses induced in parts of a screw connection.

The factors of safety for the screw and plates used in the screw connection are also calculated. The results of calculation are displayed in the Screw Calculation dialog box and can be inserted into the drawing.

You can perform the calculation on an existing 2D or 3D screw connection in the drawing or as a standalone calculation. You can also use the screw calculation feature while creating a screw connection.

The screw calculation feature supports screw connections with:

• Concentric or eccentric loads
• Nut or without nut
• Studbolt connection
• Unlimited number of plates
• Unlimited number of cylindrical shaft sections
• User-defined geometry for contact areas

For screw connection with more than two plates, you can only perform screw calculation at one contact area at one time. Generally, the following assumptions are considered when performing the screw calculation:

• Screw connection contains one screw and one nut at the most
• Screw is always positioned at the center of gravity of the contact area
• Nut and screw are of the same material
• the maximum number of washers under the head of the screw or under the nut is 2.
• ideal stiff plates

Note: Only static loads are supported by the screw calculation feature. When defining the axial load, you may select Dynamic in the Axial Loads tab of the Screw Connection dialog box to specify a minimum and a maximum value for the force and to perform calculation at these two values simultaneously.