Modeling is categorized into 3 main categories. They are as follows.
The following RODA components are and parameters can be defined under this category.
Allows for definition of the distributed beam mass and stiffness data in form of a uniform cylindrical segment. This element is defined and picturized as a shell element in ANSYS.
The data represented by this element can define both mass and stiffness, mass only or stiffness only segments.
The active beam number is highlighted inside a box to prompt the user for the active beam number information. The user can also specify the material number assigned to the element against the "Enter material number" entry box.
The cylindrical element can be created either using "Keypoints" or "nodes" options. In both of these options user is asked to specify left edge and right edge locations along with the outer and inner radii locations. RODA code 6.M is used to define this element inside the roda input file.
Below shown is a screen capture of the part of the roda input file (roda_in) for this element.
The creation is similar to cylindrical segment with the difference of asking the left edge inner/outer and right edge inner/outer locations. The output code is same as in cylinder.
This defines a cone between two stations. Code 17.M is used to define this element inside the roda input file.
Below shown is a screen capture of the part of the roda input file (roda_in) for this element.
The station at the left end of the code is specified and the cone extends to the next axial location of the same beam as S1.
The following RODA components are and parameters can be defined under this category.
Defines station numbers and locations for a specified beam. They are defined at the ends of a beam and given a radial location equal to "-ActiveBeamNumber" (- represents a minus sign). So, if the active beam is Beam1, then the stations are plotted at the radial distace of -1.0. so on and so forth. They are plotted in cyan-blue color.
Using the option "Roda stations" under "List" menu item we can review the station information.
Below is the screen shot for the stations definition inside roda input file (roda_in)
Provides a capability of adding mass to selected beam stations in the model. Using this option will bring up another pop-up gui as shown below for asking user the various parameters value. These elements are plotted in green color.
A screen shot from the roda input file.
Allows definition of mass station exclusive of beam in the model. They are particularly useful in modeling series stiffness and damping connections, for use with supports such as squeeze film dampers.
Using this option will bring up another pop-up gui as shown below for asking user the various parameters value. These elements are plotted in red color and at the radial location equal to -0.5.
A screen shot from the roda input file.
Same as stations. They are exclusive of a beam number.
They are plotted in orange color and at the radial location equal to -0.5.
A screen shot from the roda input file.
A connection to the ground. They are exclusive of a beam number.
They are plotted in white color and at the radial location equal to -0.5. Their output is not written inside the roda input file.
The following RODA components are and parameters can be defined under this category.
- Translational stiffness
- Translational damper
- Rotational stiffness
- Rotational damper
- Constraint
- Squeeze film damper
- Rub
- Speed dependent stiffness
| Following are the two sample examples where, the GUIs get popped-up to ask values from the user to define the connections between station-to-station or station-to-ground.
|
| Translational support stiffness |
Constraint |
|
|
For the translational and rotational stiffness/damping connections either of the 4 stiffness values supplied would work. The RODAPre will fill in other values assuming the symmetric matrix and rest as zeros.
In case of an insufficient data the following message will pop-up and decision will be made based on its return value.
A sample screen shot from the roda input file is shown below.
