Topology optimization currently considers only structural properties such as stiffness or eigenfrequencies. In addition, manufacturing constraints can be taken into consideration as well.
Manufacturing costs, which do not belong to the targets of topology optimization algorithms, are indeed an important factor for companies.
This article focuses on the sheet metal welding structures. These structures are popular in the machinery industry since they can be quickly built by welding steel plates, which mitigates the costs. At the same time, sheet metal welding structures have the potential of becoming leightweight. Correctly designed, metal sheet plates will carry only in-plane stresses, thus providing high stiffness with less weight.
But how do I know if my sheet metal welding structure is optimal?
Applying topology optimization to a sheet metal welding structure will produce holes into the metal sheets and that definitely increases development and production costs. This is a very typical issue our customers have been facing.
When topology optimization is employed on a block of design space, it creates a wild shape, which is difficult to convert into a sheet metal structure.
The most effective way to optimize a sheet metal welding structure is to optimize the thickness of each metal sheet or, optionally, groups of sheets. The next step then will be numerical optimization combined with finite element analysis (FEA).
Here we find the first challenge to tackle: in a sheet metal welding structure there are lots of sheets. The number of design variables would be too high for parameter optimization. The FEA would take an enormous amount of time and it is not even guaranteed it provides us with the global optimum.
As a solution, we at Meshparts developed a new topology algorithm that combines the advantages of both topology and parameter optimization. This algorithm can handle sheet metal welding structures targeting the thickness of single or groups of sheets.
This algorithm is integrated in the Meshparts Software, which is an assembly based finite element pre/post software with integrated library of ready-to-use finite element models.
The advantage of this new approach is that we can optimize sheet metal welding structures without noteworthy increase in manufacturing costs. Also, the result of the topolgy optimization requires no interpretation and can be directly manufactured as it is.
We carried out optimization both on academic examples and real structures of our customers. The conclusion is: we can save approximately 30%-40% of the original mass at equal stiffness just by optimizing metal sheet thickness. Or we can increase stiffness with the same amount without changing the mass.
More infomation can be found on http://www.meshparts.de/topoad