Guidelines for Gravity Loads
• You can define only one gravity load per load set.
• You cannot review a resultant gravity load. (Each load set is calculated separately.)
• Gravity loads are body loads available only in Structure. These loads simulate the force of gravity as it affects your model. When you define a gravity load, you specify the gravitational components of the load in each coordinate direction.
• In specifying gravity, you enter values that define gravitational acceleration, expressed as distance/time2. You can enter a positive or negative value. The sign you enter defines the direction of gravity relative to the WCS or to another Cartesian coordinate system.
• When choosing a sign, understand that a negative value opposes the coordinate direction. For example, if you want to simulate a downward gravitational force of 1G (386.4 in/sec2) in the Y direction, and you are working in in/sec2, you enter –386.4 in the Y entry box.
If you simply enter 386.4, the gravitational force would be upward.
• For 3D models, gravity is relative to the WCS or to another Cartesian coordinate system you choose as the reference. For 2D models, gravity is relative to the reference coordinate system for the 2D model or to another Cartesian coordinate system you choose as the reference.
• When you apply a gravity load, the software displays a gravity icon at the origin of the WCS. The icon includes a vector that indicates the direction of the load. If the vector direction does not agree with what you thought you specified, review the load.