STL files to CAD format for topology optimized structures

Examensarbete för masterexamen
Siva, Gopinath
Recently, topology optimization technique has acquired lot of interest across the industries because of its ability to develop lightweight efficient designs that also brings other functional benefits. But one of the difficulties is the complexity of the design to manufacture. Recent developments prove that complex designs can be easily manufactured using additive manufacturing. With the synergy of topology optimization and additive manufacturing, industries are aiming to gain more bene fits. Siemens Energy, with the knowledge and capability to manufacture components using additive manufacturing, is now interested in implementing non-traditional de sign technique like topology optimization to take the next leap in the development of its products. In the process of implementation, Siemens Energy face some issues in handling the STL geometries from topology optimization. The STL files possess some defects that prevent the engineers to use the geometries similarly to other files handled in CAD system. This thesis is to develop a method to repair the STL issues within Siemens NX environment and transform the STL file to CAD format. The method would assist design engineers at Siemens Energy to fix the STL issues in future that enable the STL geometry to be used similarly to other CAD files. The thesis also explores the feasibility of automation of the repairing process in order to reduce the manual labour. This was achieved by the exploratory study that began with literature review to explore about STL file format and various STL errors followed by exploration of Siemens NX CAD in the direction to repair STL. Later automation feasibility was investigated in NX. The method to fix STL issues is devised using use cases. STL issues were successfully addressed to develop a CAD format of the models using NX CAD. The limitations and feasibility of automation in NX was studied. NX Open tool with C# language was used in the project. A method that shall help the design engineers to fix the STL issues is proposed. In the end, future work towards automation and other possible explorations are summarised.
Polygon modeling, STL error repair, Siemens NX CAD, Automation in NX
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