ABAQUS :-i'm trying to tilt a rigid body with point structural mass by tilting a rigid platform acting as ground , the whole body is under gravity, i have to analyze the counter bars standing, while trying the issue the following error was shown. "Rotary inertia for the rigid bodies with the reference nodes listed below are not positive definite. Abaqus/Explicit now requires rigid bodies to have positive definite rotary inertia unless rotational constraints are applied with the *BOUNDARY option (see the Abaqus Analysis Users Manual). Nodes that are part of a rigid body do not require mass and inertia individually, but the rigid body as a whole must possess positive definite rotary inertia unless constraints are used. To remedy this error, either add rotational constraints to the reference nodes with the *BOUNDARY option or add inertia using the *ROTARY INERTIA option, whichever is appropriate to obtain the desired response. A node set named "ErrNodeRefNodeNoRot1Axis" containing the problematic reference nodes is also created for use in Abaqus/Viewer to help locate the error and modify the input definition." ErrNodeRefNodeNoRot1Axis is the point of inertia assigned.