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Item type:Publication, Access status: without files , Simultaneous topology and fastener layout optimization of assemblies(2021-04); Publicationtype: Conference Presentation64 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Simultaneous topology and fastener layout optimization of assemblies considering joint failureThis paper provides a method for the simultaneous topology optimization of parts and their corresponding joint locations in an assembly. Therein, the joint locations are not discrete and predefined, but continuously movable. The underlying coupling equations allow for connecting dissimilar meshes and avoid the need for remeshing when joint locations change. The presented method models the force transfer at a joint location not only by using single spring elements but accounts for the size and type of the joints. When considering riveted or bolted joints, the local part geometry at the joint location consists of holes that are surrounded by material. For spot welds, the joint locations are filled with material and may be smaller than for bolts. The presented method incorporates these material and clearance zones into the simultaneously running topology optimization of the parts. Furthermore, failure of joints may be taken into account at the optimization stage, yielding assemblies connected in a fail-safe manner.Publicationtype: Journal ArticleScopus© Citations 11 304 234 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Density-based shape optimization for fail-safe designThis paper presents a two-stage procedure for density-based optimization towards a fail-safe design. Existing approaches either are computationally extremely expensive or do not explicitly consider fail-safe requirements in the optimization. The current approach trades off both aspects by employing two sequential optimizations to deliver redundant designs that offer robustness to partial failure. In the first stage, a common topology optimization or a topology optimization with local volume constraints is performed. The second stage is referred to as “density-based shape optimization” since it only alters the outline of the structure while still acting on a fixed voxel-type finite element mesh with pseudo-densities assigned to each element. The performance gain and computational efficiency of the current approach are demonstrated by application to various 2D and 3D examples. The results show that, in contrast to explicitly enforcing fail-safety in topology optimization, the current approach can be carried out with reasonable computational cost. Compared to the local volume constraint approach, the suggested procedure further increases the fail-safe performance by 47% for the example considered.Publicationtype: Journal ArticleScopus© Citations 24 203 283 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Fail-safe design of topology optimized structures using density-based member shaping(2019-09); Publicationtype: Conference Presentation52 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Adaptive strategies for fail-safe topology optimizationConsidering fail-safe requirements in a topology optimization, where the location of the damage is unknown in advance, leads to a high number of potential damage scenarios to be calculated. Since this is driving the overall calculation time of the optimization, a reduction of the considered damage cases is desirable. In this paper, two strategies to achieve a significant reduction of damage cases are shown: An active-set strategy as an extension to the simplified local damage model first introduced by Jansen et al. as well as a newly developed load-path based algorithm for the placement of damage zones.Publicationtype: Conference Paper73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Comparison of structural topology, shape and sizing optimization of an aircraft fuselage door surround structure(2017-11-08); The ongoing development of additive manufacturing processes allows for building large-scale structures with dimensions of several meters. Together with structural optimization techniques, lightweight structures with a high specific stiffness can be designed and manufactured. One promising field of application are airframe structures. However, the difference in orders of magnitude of the whole part in a range of meters to the size of individual features of millimeters makes the optimization a computationally demanding task. In the current work, a fuselage panel with door cutout (i.e. a door surround structure) is optimized using different well-known optimization techniques. Topology optimization is expected to be the most flexible approach. However, if the optimal solution consists of thin-walled stiffeners, it is extremely expensive to derive such a design with topology optimization. Therefore, alternatively an isogrid of stiffeners is considered and optimized with shape and sizing optimization. For shape optimization, the height of the stiffeners is treated as variable. For sizing optimization, the thickness is varied. The current work compares all three optimization approaches (topology, sizing and shape optimization) in terms of effort versus performance of the optimized part. Though topology optimization in general allows for describing the solution obtained by the other approaches, it requires a very fine mesh to represent thin-walled stiffeners. Similar designs with the same performance are also obtained by shape or sizing optimization at significantly less computational cost.Publicationtype: Conference Presentation64