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Entwicklung einer regelbasierten Vorgehensweise zum automatisierten Aufbau kraftflussangepasster Gitterstrukturen und Implementierung in NXOpen

 
: Omasreiter, Stefan

Augsburg, 2013, 73 pp.
Augsburg, Hochschule, Bachelor Thesis, 2013
German
Bachelor Thesis
Fraunhofer IWU ()
Leichtbau; Gitter; additive Fertigung; Generative Fertigung

Abstract
Lightweight design is one of the latest trends in engineering cars, planes or ships. Lightweight design can be subdivided in several sections, such as material-optimated or load-adapted lightweight design. Thereby, load-adapted lightweight design is influenced by bionic construction principles such as load-adapted insect wings of a dragonfly or the alignment of wooden-fibres during growth in trees.
The Siemens Software NX 8.0 enables to simulate various workload cases with its FEM-tool which can help to show the flux of force in a loaded component. Therefor the whole building part is divided in small elements on whose nodes tension-values are calculated. This work discusses and examines the process from FEM-Postprocessing of the respective part, to automatically ascertaining the pathways of the flux of force, till building a load-adapted lattice structure.
For this purpose, it is senseful to automate various steps of the building process of the lattice structure in a coding project. This strategy enables a low-effort application of the approach for various load cases and components. The current tool was programmed in the Microsoft Software Visual Studio 2010 in the coding language C#. First of all precursor-projects are described and it is accurately checked, what types of Siemens NX functions are needed for the coding project. Short explanations of used Siemens NX 8.0 instruments are exposed in the next chapter. Next up, there is declared, what information the operator has to provide in the Windows-Forms menu after executing the programmed tool via the programming interface NXOpen. Additional, explanations of some of most important sections of the coding project show, how the coding project works and behaves.
Barely explained, the procedure of generating a lattice structure is as follows: The tool subsequently calculates the flux of force from a starting point in one main-tensor-direction with the aid of the FEM-Postprocessing data. This flux is called lead-curve. After finishing that calculation, a number of points on the lead-curve are used to calculate directives in a further main-tensor-direction.
At the end, these directives are used to place a freeform surface between them. Because there are three main-tensor-directions occurring in every work-load case, there are three possibilities to combine respectively two of them. After completing the construction of all freeform-faces, they can be pruned with each other. The resulting intersections can be connected with lines and express a structure of curves.
These curves can now be covered with round rods to create 3D solid body. After some manual amendments the lattice structure was built by additive Manufacturing. In the current work these steps were as far as possible automated within the scope of developing a universal approach for building load-adapted three-dimensional lattice structures. Last but not least a brief look in the future reveals how the project could be proceeded and what prospects could arise.

: http://publica.fraunhofer.de/documents/N-274036.html