A Node in finite element analysis represents a joint or support point. In OpenBrIM, a Node has six degrees of freedom: three for translation (in the X, Y, and Z directions), and three for rotation (around the X, Y, and Z axes).
In the context of a 3D structure, it's possible for two components to share the same location, such as the top of one component and the bottom of another component that sits on top of it. OpenBrIM handles this scenario by automatically merging the nodes that represent these points before moving on to the analysis phase.
In OpenBrIM, all six degrees of freedom (translation in X, Y, and Z, and rotation around X, Y, and Z) are set to "free" by default, meaning the nodes can translate and rotate as long as the connected elements allow it. The Tx, Ty, Tz, Rx, Ry, and Rz parameters can be used to specify the support status of each degree of freedom. A value of zero means the degree of freedom is free (default), a value of -1 means it's fully fixed, and any other value is interpreted as the stiffness of that node (partial fixity).
It's also worth noting that the X, Y, and Z parameters can be abbreviated.
Example Syntax:
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<O N="Node1" T="Node" X="0" Y="0" Z="0">
...
...
</O> |
Example:
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When you access the Analytical View in OpenBrIM and navigate to the settings, a combobox will appear as shown in the figure. If you select the "Display Supports" option, it will display the degree of freedom status for each point or support. As a result of the values given to the DOF (Degree of Freedom) parameters, the Analytical View will change as follows.
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There is no changed parameter. All degrees of freedom are fixed. |  | |||||
This is the changed parameter → Tx=”1” Tx's degree of freedom is free. |  | |||||
This is the changed parameter → Ty=”1” Ty's degree of freedom is free. |  | |||||
This is the changed parameter → Tz=”1” Tz's degree of freedom is free. |  | |||||
This is the changed parameter → Rx=”1” Rx's degree of freedom is free. |  | |||||
This is the changed parameter → Ry=”1” Ry's degree of freedom is free. |  | |||||
This is the changed parameter → Rz=”1” Rz's degree of freedom is free. All parameters have "free" degrees of freedom, meaning that they can rotate freely without any resistance to external forces. |  | |||||
To view this example in the library, see (https://openbrim.org/platform/?application=inc&author=ParamML_Examples_OpenBrIM+Platform&obj=objid0mtzu87tzzfne2q67hyl6m) | ||||||
Parameters of Node Object:
Label | Mandatory | Name and Type Attributes | Default Description and Value Attributes | Other Attributes |
X coordinate | Yes | N="X" | D="X: The x coordinate of the point." V="0" | UT="Length" UC="Coordinate" |
Y coordinate | Yes | N="Y" | D="Y: The y coordinate of the point." V="0" | UT="Length" UC="Coordinate" |
Z coordinate | Yes | N="Z" | D="Z: The z coordinate of the point." V="0" | UT="Length" UC="Coordinate" |
X-direction Translational Fixity | Yes | N="Tx" | D="Tx: The translational fixity in x direction (0 for free, -1 for fixed, K stiffness value otherwise)" | Role="Input" |
Y-direction Translational Fixity | Yes | N="Ty" | D="Ty: The translational fixity in y direction (0 for free, -1 for fixed, K stiffness value otherwise)" | Role="Input" |
Z-direction Translational Fixity | Yes | N="Tz" | D="Tz: The translational fixity in z direction (0 for free, -1 for fixed, K stiffness value otherwise)" | Role="Input" |
X-axis Rotational Fixity | Yes | N="Rx" | D="Rx: The rotational fixity about x axis (0 for free, -1 for fixed, K stiffness value otherwise)" | Role="Input" |
Y-axis Rotational Fixity | Yes | N="Ry" | D="Ry: The rotational fixity about y axis (0 for free, -1 for fixed, K stiffness value otherwise)" | Role="Input" |
Z-axis Rotational Fixity | Yes | N="Rz" | D="Rz: The rotational fixity about z axis (0 for free, -1 for fixed, K stiffness value otherwise)" | Role="Input" |