Topology optimization for fail-safe designs using moving morphable components as a representation of damage

Designs obtained with topology optimization (TO) are usually not safe against damage. In this paper, density-based TO is combined with a moving morphable component (MMC) representation of structural damage in an optimization problem for fail-safe designs. Damage is inflicted on the structure by an MMC which removes material, and the goal of the design problem is to minimize the compliance for the worst possible damage. The worst damage is sought by optimizing the position of the MMC to maximize the compliance for a given design. This non-convex problem is treated using a gradient-based solver by initializing the MMC at multiple locations and taking the maximum of the compliances obtained. The use of MMCs to model damage gives a finite element-mesh-independent method, and by allowing the components to move rather than remain at fixed locations, more robust structures are obtained. Numerical examples show that the proposed method can produce fail-safe designs with reasonable computational cost.

Topology Optimization Design of Filling Bodies in an Umbilical Based on Moving Morphable Components Theory

Umbilical is an indispensable link of offshore oil & gas resource development equipment for underwater production system, which are mainly composed of functional components such as steel tubes, electric cables and optical cables are in a helically wound structure. Filling bodies are required to support these functional components for improving anti-crushing capacity and fatigue life. Filling bodies have a significant impact on the mechanical and physical properties, which triggers the optimization design of filling bodies. However, the complexity of filling body space brings challenge to the optimization design. Moving Morphable Components (MMC) theory is introduced to topological optimization method in complicated filling body space with the objective of mechanical properties. The results show that the optimized filling bodies can effectively reduce structural weight with the same mechanical properties. Numerical models of cross-sections of umbilicals with the optimized filling bodies are constructed, the cross-sectional mechanical properties are compared with that under the initial filling body form, which can fully verify the feasibility and correctness of this optimization design strategy.

Topological Optimization of Under-Platform Dampers With Moving Morphable Components and Global Optimization Algorithm for Nonlinear Frequency Response

To limit the risk of high cycle fatigue, underplatform dampers (UDPs) are traditionally used in aircraft engines to control the level of vibration. Many studies demonstrate the impact of the geometry of the damper on its efficiency, thus the consideration of topological optimization (TO) to find the best layout of the damper seems natural. Because of the nonlinear behavior of the structure due to the friction contact interface, classical methods of TO are not usable. This study proposes to optimize the layout of an UDP to reduce the level of nonlinear vibrations computed with the multiharmonic balance method (MHBM). The approach of TO employed is based on the moving morphable components (MMC) framework together with the Kriging and the efficient global optimization algorithm to solve the optimization problem. The results show that the level of vibration of the structure can be reduced to 30% and allow for the identification of different efficient geometries.