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Quasi-static motion components

The QS Motion tab defines a list of individual quasi-static displacements applied to any structural model components (such as Lines, Floaters; Rigid Bodies, Buoys, etc) that may be used to define combined environments from the Combination matrix tab.

Note

Prescribed displacements that may be defined within the QS motion tab are specified based on the translations along the global XYZ-axes and the 3 rotations about the global XYZ-axes. It may be more convenient to use the Offset tab to define horizontal displacements applied to Floater components (since offset are setup with the amplitude and heading rather than XYZ displacement components).

The QS Motion tab includes 2 sheets labeled Motion List and Quasi-static Evolution.

Motion list data sheet

The Motion List sheet includes the following items:

  • Number of motions: The number of QS motion components must be set with the spin box located in the upper right corner of the tab. You may either use the up/down arrows to setup the number of QS motions, or input any value using your keyboard and then pressing the ENTER key. Pressing the ENTER key confirms the number of individual components to be included and generates the main QS motion data table with appropriate number of rows.

  • Insert new motion: Pressing this button inserts a new row in the main QS motion data table.

  • Remove selected motion: Pressing this button deletes the selected rows from the main QS motion data table.

  • QS motion data table: This table is used to define the QS motion data. This table includes 11 columns, as follows:

    • Name: This assigns names that will be used to refer to the QS motion components in the Combination matrix tab.

    • Object: Used to select the structural model component to which the QS motion will apply. Each cell in this column contains a drop-down list filled in with the names of all structural components available in the model (including lines, floaters, rigid bodies, buoys, etc.).

    • Location: Used to select the point on the structural component at which the QS motion will apply. Each cell in this column contains a drop-down list filled in with the list of points that is available with the selected structural model component (e.g. including the COG and all fairleads/hang-off points for Rigid bodies, Buoys and Floaters, and including all primary connection points for Lines).

    • Evolution: This option sets the quasi-static evolution that is to be associated with each QS motion component. The following items are available:

    • Default: Selecting this option instructs the software that the quasi-static evolution which is defined in the Quasi-static evolution tab shall be used.

    • Linear: Selecting this option supersedes the quasi-static evolution that is defined in the Quasi-static evolution tab. "Linear" means that the QS motion is applied progressively with a linear ramp between the first quasi-static step (i.e. no displacement at step 0)and the last quasi-static step (i.e. complete displacement at the last quasi-static step).

    • User defined: Selecting this option supersedes the quasi-static evolution that is defined in the Quasi-static evolution tab. "User defined" allows selecting the rate of QS motion amplitude that is considered as a function of the quasi-static step.

    • Edit button: This button is only enabled in case the user-defined QS evolution is set as "User-defined". Pressing the button raises a window allowing to set the data related to the user-defined evolution.

  • X (m): Defines the quasi-static translation along the global X-axis.

  • Y (m): Defines the quasi-static translation along the global Y-axis.

  • Z (m): Defines the quasi-static translation along the global Z-axis.

  • RX (m): Defines the quasi-static rotation about the global X-axis.

  • RY (m): Defines the quasi-static rotation about the global Y-axis.

  • RZ (m): Defines the quasi-static rotation about the global Z-axis.

Quasi-static evolution data sheet

The Quasi-static evolution tab is used to set an evolution law (i.e. the ratio of displacement applied as a function of the quasi-static load step) that will be common to all QS motion components.

  • Linear means that the QS motion is applied progressively with a linear ramp between the first quasi-static step (i.e. no displacement at step 0)and the last quasi-static step (i.e. complete displacement at the last quasi-static step).

  • User defined allows selecting the rate of QS motion amplitude that is considered as a function of the quasi-static step.

An example of QS Motion tab is shown below: