10.9.1.1. RFlex Modal Load Case

Modal Load Case is a load library and can be used in Modal Force and Modal Preload in RecurDyn/RFlex. A following figure shows a concept of using method of Modal Load Case.

If the user has an obvious load case applied on a RFlex body, first, defines Modal Load Cases. In the following figure, the distributed force can be defined as load cases. After the load cases can be translated to a generalized force as following Modal Load Cases \({{\mathbf{f}}_{1}},\ {{\mathbf{f}}_{2}},\ ...,\ {{\mathbf{f}}_{9}}\). In each simulation time, the user can calculate easily a load for a RFlex body on the current simulation time through calculating 9 scale factors for each Modal Load.

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Figure 10.100 Concept of Modal Load Case

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Figure 10.101 Modal Load Case dialog box

  • Load Name: Displays a name of modal load case. The user can modify the name.

  • Body Name: Displays a name of selected RFlex body.

  • …: Executes the Definition Modal Load dialog and shows the detail information of selected modal load case.

  • Add: Adds a Modal Load Case of a RFlex body.

  • Delete: Deletes a selected modal load case.

  • Import: The user can make modal load cases using a MLC file. The MLC file is a modal load case information file.

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    Figure 10.102 Import Modal Load Case dialog box

  • Export: The user can make a MLC file including data of selected Modal Load Cases.

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    Figure 10.103 MLC file

    • $: Comment

    • MLC MLCID MLCNAME: Define a modal load case. The modal load case cannot have Modal Load type and Nodal Load type, simultaneously. The modal load case can have one more loads of Nodal Load type and just one load of Modal Load type.

    • LOAD NL MLCID NODEID fx fy fz tx ty tz: Define a load of Nodal Load type.

    • LOAD ML MLCID NOMODE fx fy fz tx ty tz mode1 mode2 mode_m: Define a load of Modal Load type.

10.9.1.1.1. Definition Modal Load

Nodal Load type

The user can make a Cartesian load on a node. A modal load case has one or more loads of Nodal Load type.

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Figure 10.104 Definition Modal Load [Nodal Load]

  • RFlex Body: Displays a name of selected RFlex body.

  • Load Name: Displays a name of modal load case. This name can be modified in the Modal Load Case dialog box.

  • Node ID: Writes a node id of selected RFlex body.

  • FX, FY, FZ: Force vector on the node id with respect to the reference frame of RFlex body.

  • TX, TY, TZ: Torque vector on the node id with respect to the reference frame of RFlex body.

  • N Button: Executes Node Selection Dialog.

  • Add: Adds a load of the Nodal Load type.

  • Delete: Deletes selected loads of the Nodal Load type.

  • Close: Closes this dialog box.

Modal Load type

The user can directly define a converted modal force vector. The load vector size is [(6+nmode) \(\times\) 1]. The nmode is a number of all modes in a selected RFlex body.

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Figure 10.105 Definition Modal Load [Modal Load]

  • RFlex Body: Displays a name of selected RFlex body.

  • Load Name: Displays a name of modal load case. This name can be modified in the Modal Load Case dialog box.

  • Mode Seq.: Displays all modes of selected RFlex body and a generalized force and torque for the rigid motion of RFlex body.

  • Value: Inputs desired values.