For a connection with the FFlex body, dummy
body is introduced on node where a force or joint will be connected. You can
decide whether the Force connector is used between the dummy body
and node or not.
If you:
•Use Force connector, a specialized force is connected between the dummy body and node.
•This force is designed by connecting parameters such as stiffness, damping ratio.
•It is recommended that stiffness parameter be tuned to the Young's modulus of material in the FFlex body.
•However, these parameters can be suitably modified according to the characteristics of the model.
•Do not use Force connector, the fixed joint is connected between the dummy body and node. And, under this condition, you can make any force as well as any joint on the FFlex body.
Figure 1 Connecting Parameters tab of the Properties of FFlex Body dialog box
•Use Force Connector: Determines the connector type.
o If you check the option, it means that you want to use a force connector.
o On the other hand, leaving it un-checked means that you want to use a fixed joint as a connector.
•Sync. FDR: Synchronizes all FDR connector types with the FFlex body connector type.
o Some models have a lots of FDR elements and you have to change all the options that you want individually.
o It allows you to easily change these options by synchronizing it with the FFlex body connector.
o Use Force Connector is checked, and Sync. FDR is checked. (The type of the connector between Dummy Body and FFlex Body is force, and the type of all FDR elements is force too regardless the local setting for each FDR element.)
o Use Force Connector is unchecked, and Sync. FDR is checked. (The type of the connector between Dummy Body and FFlex Body is constraint, and the type of all FDR elements is constraint too regardless the local setting for each FDR element.)
o Use Force Connector is checked, and Sync. FDR is unchecked. (The type of the connector between Dummy Body and FFlex Body is force, and the type of FDR element follows to the local setting for each FDR element.)
o Use Force Connector is unchecked, and Sync. FDR is unchecked. (The type of the connector between Dummy Body and FFlex Body is constraint and the type of FDR element follows to the local setting for each FDR element.)
•Material Property of Connecting Body: Defines the properties of Dummy Body.
o Mass is 1e-006 and moment of inertia is 1 as default. It is no problem in the model which has a large mass and an inertia value for a FFlex body.
o These values should be reduced relatively in the model which has s small mass and an inertia value for a FFlex body.
o For example, if the mass of a FFlex body is 1.e-006, the mass of dummy body should be 1.e-008 as the smaller value to see the more accurate results.