Comment on page
Fig. 184.108.40.206: Display of utilization and bending moments of cantilever beam
The “BeamView” component controls the display options related to beams and trusses (see fig. 220.127.116.11). This concerns the rendering of cross section forces, resultant displacements, utilization of material and axial stress.
When activated, “Cross section”, “Displacement”, “Utilization” and “Axial Stress” result in a rendered view of the model. Utilization is calculated as the ratio between the normal stress at a point and the strength of the corresponding material. Shear and buckling are not considered.
Fig. 18.104.22.168: Left: “Cross section”-option enabled. Right: “Axial Stress” enabled.
The color range of the results starts at the minimum value and stretches to the maximum. You can define individual color ranges for all result quantities in the "karamba.ini"-file. Alternatively it is possible to select from a list of color-ranges via the component's context menu: right-click on the component, go to item 'Colors' and select a color range. A “Legend”-component lets you inspect the meaning of the colors.
The mesh of the rendered image is available at the “Mesh”-output of the “BeamView”-component. Two sliders control the mesh-size of the rendered beams: First “Length/Segment” of “ModelView” determines the size of sections along the middle axis of the beams. Second “Faces/Cross section” of “BeamView” controls the number of faces per cross-section. For rendering circular hollow cross sections the number of “Faces/Cross section” is multiplied by six in order to get a smooth visual result.
Fig. 22.214.171.124: Mesh of beams under dead weight with upper and lower results threshold set to 53% and 50%
It is instructive to see which parts of a beam are under tension or compression. Activate the “Axial Stress”-checkbox in menu “Render Settings” in order to display the stresses in longitudinal beam direction. Red (like brick) means compression, blue (like steel) tension. In some models there may exist small regions with high stresses with the rest of the structure having comparatively low stress levels. This results in a stress rendering that is predominantly white and not very informative. With the sliders for “Upper Result Threshold” and “Lower Result Threshold” of the “ModelView” you can set the range of the color-scale (see section 3.6.1). Result values beyond the upper limit appear yellow, below the lower threshold green (see fig. 126.96.36.199).
Fig. 188.8.131.52: Moment My about the local Y-Axis and shear force Vz.
The “Section Forces” sub-menu lets you plot section forces and moments as curves, meshes and with or without values attached. All generated curves and meshes get appended to the “BeamView”-component's “Curves” and “Mesh” output. The graphical representation is oriented according to the local coordinate axes of the beam and takes the deflected geometry as its base. The subscript of bending moments indicates the local axis about which they rotate, for shear forces it is the direction in which they act (see also fig. 184.108.40.206). The cross section forces refer to the section which is defined by the element's local coordinate system. In fig. 220.127.116.11 the cross section forces need to be applied to the right side of the beam to be in equilibrium with the external point load since the local X-direction points to the left side.
The size of the cross section forces diagrams can be scaled separately for forces and moments by the two sliders in the "SectionForces"-menu.
Customize the mesh-colors of the cross section forces diagrams via "karamba.ini". The slider “Length/Subdivision” in sub-menu “Render Settings” of the “ModelView”-component controls the number of interpolation points.