Modelling of a Fixed Fixation:
Bilder
A fixation can be applied to surfaces, edges and nodes
If a fixation is created for a volume the whole volume is considered fixed in the according directions. (Apex?) The fixation, considered during the optimization, can be compared to an RBE2 bracket. This means the nodes are stiff and cannot be deformed in any way.
Modelling of a Screw Fixation:
Bilder vom Modellaufbau (Apex?)
A screw fixation can be modelled by using a nondesign around the screw which is fxed in all directions.
To simulate the reality it is also possible to load in an extra volume that’s representing the screw. However the screw will not be inlcuded in the design space because it is just an help for the simulation of the reality and the screw should not be part of the finished optimization result. The screw will be used as a fixation and is considered fixed in all directions. Additionally, there should be a nondesign space around the screw, which will be included in the design space as well, but which will not be used as a fixation in the optimization model. This way the nondesign space does not experience an artificial stiffening, which represents the reality much more accurately.
Modelling of very smooth transitions between the design space and the fixed nondesign spaces:
Vergleichsbilder
Geht erst wenn verschiedene E-Module möglich sind
The transition between design and nondesign regions can be enhanced even further by adjusting the Youngs Modulus of the nondesign spaces. While reducing the Youngs Modulus by a factor of 10 the material is considered more pliant and therfore needs more material to absorb the stresses. This results in softer material transitions between the different materials and spaces
Especially for parts where the fatigue strength plays a role, this method is good to strengthen the transitions betwenn the different spaces and thus extend the durability