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*Axis/Vector

Purpose

To define axis systems and vectors for use in postprocessing.

Theory

Refer to Angles Output for further information on this feature.

Keyword Format

The keyword starts with a line defining the name of the axis system or vector. This is then followed by a line with further entries, depending on what option is being selected. Any further axis systems or vectors can be defined by repeating the two lines as often as necessary.

Lines defining an axis system, based on two orthogonal vectors:

AXIS=Axis Name

Origin Node (Number or Label), X1, Y1, Z1, X2, Y2, Z2

Lines defining an axis system, based on two nodes:

AXIS=Axis Name

Origin Node (Number or Label), LOCAL_X_NODE=Local X Node (Number or Label)

Lines defining a vector:

VECTOR=Vector Name

Origin Node (Number or Label), X, Y, Z

If you specify a node label rather than a node number, it must be enclosed in {} brackets. Any vectors defined must have non-zero length.

Axis systems (Vector-Based)

Table Input

Notes

(a)If you do not specifically input a value in any of Columns 3-8, then the corresponding variable defaults to 0. Note however that all three of X1, Y1 and Z1 or all three of X2, Y2 and Z2 cannot equal 0 – the null vector cannot be either the local x-axis or the local y-axis.

(b)Note that the local x-axis and local y-axis that you define here must be orthogonal, that is, the true angle between the two vectors defining the local x- and y-axes must be 90°. Flexcom will generate an error message if this is not the case, as vectors that are not orthogonal cannot be used to form a valid axis system.

Axis systems (NODE-Based)

Table Input

Notes

(a)The local x vector is formed by the straight line connecting the origin node to the local x node, and then normalised to a unit vector. The local y and local z vectors are formed automatically by Flexcom using cross products. As the local y and local z vectors are somewhat arbitrary, the node-based axis system definition is most useful when you are interested in one particular direction only. For example, if you would like to monitor out of plane displacements, you would set the local x vector to be perpendicular to the plane of  interest (e.g. the rotor plane of a wind turbine).

axis/vector - Vector

Table Input

Notes

(a)If you do not specifically input a value in any of Columns 3, 4 or 5, then the corresponding variable defaults to 0. Note however that all three of X, Y and Z cannot equal 0 – the angle between an element and the null vector is not a valid output.