Constraints: Common data |
Used to refer to the constraint.
A constraint's in-frame can be free, fixed, anchored or connected to another object.
Defines the position of the constraint in-frame in terms of the connection coordinates $x$, $y$ and $z$.
The azimuth, declination and gamma angles, $\phi, \theta, \gamma$, that define the orientation, $\Ixyz$, of the constraint in-frame relative to the connection axes, $\Cxyz$. These angles specify the orientation of the in-frame as follows:
In all these rotations, a positive angle means rotation clockwise about the positive direction along the axis of rotation, and a negative angle means anti-clockwise.
Three-dimensional rotations are notoriously difficult to describe and visualise. When setting the azimuth, declination and gamma, it is best to check that the resulting $\Ixyz$ directions are correct by drawing the local axes on the 3D view.
Either calculated DOFs or imposed motion.
If the solution method is indirect, then the constraint's out-frame can be independently connected to another object. Such a constraint is said to have a double-sided connection.
Note: | If the constraint has a double-sided connection, then its connection data (detailed below) determines where the out-frame will be when the model is in reset state. This is independent of the position of the in-frame. OrcaFlex does not attempt to enforce the usual relationship between the in-frame and the out-frame (e.g. any fixed internal degrees of freedom for a Cartesian constraint) until the analysis begins. It is possible to specify out-frame connection data that is incompatible with the defined relationship between the in-frame and the out-frame; such models are insoluble and will fail to converge. It is important to be aware of such potential pitfalls when building models with constraints that have double-sided connections. |
If a constraint has a double-sided connection, then its out-frame can independently be free, fixed, anchored or connected to another object.
Note: | The out-frame connection applies in addition to the usual relationship between the in-frame and the out-frame. For instance, a free out-frame ostensibly has six free degrees of freedom; however, OrcaFlex may eliminate some or all of these (once the analysis is underway) in order to enforce the stated conditions between the in-frame and the out-frame (such as a particular internal degree of freedom, e.g. $x$, being fixed on the degrees of freedom page). |
Defines the position of the constraint out-frame in terms of the connection coordinates $x$, $y$ and $z$. These data are only available if the constraint has a double-sided connection.
The azimuth, declination and gamma angles, $\phi, \theta, \gamma$, that define the orientation, $\Ixyz$, of the constraint out-frame relative to the connection axes, $\Cxyz$. These angles have the same meaning as their in-frame equivalents and are only available if the constraint has a double-sided connection.