Topology optimisation for 3D printing
Additive manufacturing, unlike traditional machining techniques, makes it possible to produce parts with complex geometries whose total weight can be optimised using a numerical method called “topology optimisation”.
This technique literally consists of “removing” the material where the efforts do not transit using an optimisation software. Among the best known are the DesignSpace software from Ansys, Tosca from Dassault Systèmes, Autodesk Within Labs and SolidThinking Inspire.
Topology optimisation, how does it work?
Topology optimisation starts with the creation of a coarse 3D model during the design or by the use of an already existing part for an evolution to which one will apply different loads and forces supported by the part (a pressure on fixing lugs for example).
The software is then responsible for calculating all the constraints applied, represented in red (the indispensable elements of the part) and in blue (the elements having no use).
At this level, a cutting of the piece can be done to remove the parts not subject to efforts. A draft of the future optimized part is then already visible.
The final geometry, meeting both mechanical and design requirements, can then be finally achieved after smoothing the workpiece.
To gain an idea of the gain, the following piece had an initial weight of 2kg and could be optimised to weigh only 327g, a gain of 83.4% for a mechanical strength meeting the specifications.
Who uses topology optimisation and for what purposes?
The automobile has quickly addressed this problem for reasons of reducing direct costs through the commodity economy associated with the series sizes. Indeed, a gain of a few grams per vehicle, on a production of several million units, represents tons of material saved.
Aeronautics, for its part, has been interested in reducing indirect costs. A lighter aircraft consumes less fuel which in the long run generates significant savings for an airline.
In the automobile industry, casting is the predominant method that allows us to approach this kind of complex profiles. In contrast, with the technique of machining in the mass mainly used in aeronautics, these forms are difficult to achieve. This constraint is all the more true if the part has a closed contour, in the manner of a mechanism enclosed in a trunk, preventing any operation via a conventional method.
Nowadays, additive manufacturing overcomes these problems, giving designers more freedom in design while reducing material costs and fuel costs.
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