Alpaca4d

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Nodal Displacements ​

Displacement, rotation, velocity and acceleration at every node of the model.

🔧 Grasshopper component ​

Nodal DisplacementsAlpaca4d ▸ 08_NumericalOutput
Nodal Displacements component
Inputs
AlpacaModelModelThe analysed model.
HistoryBooleanfalseRead every recorded step instead of one.
Each output becomes a tree {step} holding that step's value per node. Step is ignored.
StepInteger0Analysis step, or mode number for a modal model.
NodeTagIntegerlist(empty)Read only these nodes, by tag.
Empty reads every node.
Outputs
PositionPointlistWhere each node read sits, undeformed.
Read with NodeTag, this is what ties the results back to the model.
DisplacementVectorlistTranslation at each node, in m, global axes.
RotationVectorlistRotation at each node, in rad, global axes.
--------—A visual separator. Nothing comes out of it.
VelocityVectorlistVelocity, in m/s, global axes.
Transient analysis only.
AngularVelocityVectorlistAngular velocity, in rad/s, about the global axes.
Transient analysis only.
AccelerationVectorlistAcceleration, in m/s², global axes.
Transient analysis only.
AngularAccelerationVectorlistAngular acceleration, in rad/s², about the global axes.
Transient analysis only.

The lists are ordered by node tag, which is the order Assemble numbered the nodes in — not the order you drew anything. Read with NodeTag, they hold the nodes asked for, still in tag order.

📈 When to use it ​

Use it when

  • You need a deflection to check against a limit.
  • You want the displaced shape as data rather than as a picture.
  • You are extracting a response history at a control node: sweep Step and collect one component.

Do not use it when

  • You only want to look at the deformed shape → Model View draws it directly.

Note

On a model from Natural Vibration, Displacement is the mode shape, and Step selects the mode. Each mode is scaled so that its largest translation is 1, and its rotations by the same factor, so the magnitudes are not physical displacements — only their relative values mean anything.