Effect of stiffness anisotropy on topology optimisation of additively manufactured structures

2018 ◽  
Vol 171 ◽  
pp. 842-848 ◽  
Author(s):  
Louis N.S. Chiu ◽  
Bernard Rolfe ◽  
Xinhua Wu ◽  
Wenyi Yan
Keyword(s):  
Topology Optimisation ◽  
Stiffness Anisotropy

SIMP for Complex Structures

2016 ◽  
Vol 846 ◽  
pp. 535-540
Author(s):  
David J. Munk ◽  
David W. Boyd ◽  
Gareth A. Vio
Keyword(s):  
Natural Frequencies ◽  
Dynamic Loads ◽  
Topology Optimisation ◽  
Complex Structures ◽  
Structural Failure ◽  
Frequency Range ◽  
Aerodynamic Loading ◽  
Frequency Excitation ◽  
Wing Structure ◽  
Lifting Surfaces

Designing structures with frequency constraints is an important task in aerospace engineering. Aerodynamic loading, gust loading, and engine vibrations all impart dynamic loads upon an airframe. To avoid structural resonance and excessive vibration, the natural frequencies of the structure must be shifted away from the frequency range of any dynamic loads. Care must also be taken to ensure that the modal frequencies of a structure do not coalesce, which can lead to dramatic structural failure. So far in industry, no aircraft lifting surfaces are designed from the ground up with frequency optimisation as the primary goal. This paper will explore computational methods for achieving this task.This paper will present a topology optimisation algorithm employing the Solid Isotropic Microstructure with Penalisation (SIMP) method for the design of an optimal aircraft wing structure for rejection of frequency excitation.

Design of bending dominated lattice architectures with improved stiffness using hierarchy

2018 ◽  
Vol 233 (11) ◽  
pp. 3976-3993 ◽  
Author(s):  
Maen Alkhader ◽  
Mohammad Nazzal ◽  
Karim Louca
Keyword(s):  
Finite Element ◽  
Cell Walls ◽  
Detrimental Effect ◽  
Diamond Lattice ◽  
Finite Element Simulations ◽  
Deformation Mechanisms ◽  
Manufacturing Processes ◽  
Cellular Solids ◽  
Stiffness Anisotropy

Micro-architectured lattices are a promising subclass of cellular solids whose inner topologies can be tailored to enhance their stiffness. Generally, enhancing lattices' stiffness is achieved by increasing their connectivity. This strategy gives rise to a stiffer response by forcing lattices' ligaments to deform mainly in an axial manner. Conversely, this work is interested in developing micro-architectured lattices with enhanced stiffness, but whose cell walls deform in a flexural manner. Such structures can be more ductile and exhibit better energy mitigation abilities than their stretching dominated counterparts. Enhancing the stiffness of bending dominated lattices without increasing their connectivity can be realized by transforming them to hierarchical ones. This work explores, using experimentally verified finite element simulations, the effect of fractal-inspired hierarchy and customized nonfractal-based hierarchy on stiffness, anisotropy, and deformation mechanisms of an anisotropic bending dominated diamond lattice. Results show that fractal-inspired hierarchy can significantly enhance the stiffness of bending dominated lattices without affecting their deformation mechanisms or anisotropy level; ill-designed hierarchy can have a detrimental effect on lattice's stiffness; and customized hierarchy are more effective than fractal-inspired hierarchy in enhancing lattices' stiffness as well as can be more compatible with traditional, reliable, mass-producing manufacturing processes.

Design of an Air-Cooled Radial Turbine: Part 1 — Computational Modelling

2018 ◽  
Author(s):  
Yang Zhang ◽  
Tomasz Duda ◽  
James A. Scobie ◽  
Carl M. Sangan ◽  
Colin D. Copeland ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Experimental Testing ◽  
Temperature Drop ◽  
Computational Modelling ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Topology Optimisation ◽  
Internal Cooling ◽  
Element Analysis ◽  
Radial Turbine

This paper is part of a two-part publication that aims to design, simulate and test an internally air cooled radial turbine. To achieve this, the additive manufacturing process, Selective Laser Melting (SLM), was utilized to allow internal cooling passages within the blades and hub. This is, to the authors’ knowledge, the first publication in the open literature to demonstrate an SLM manufactured, cooled concept applied to a small radial turbine. In this paper, the internally cooled radial turbine was investigated using a Conjugate Heat Transfer (CHT) numerical simulation. Topology Optimisation was also implemented to understand the areas of the wheel that could be used safely for cooling. In addition, the aerodynamic loss and efficiency of the design was compared to a baseline non-cooled wheel. The experimental work is detailed in Part 2 of this two-part publication. Given that the aim was to test the rotor under representative operating conditions, the material properties were provided by the SLM technology collaborator. The boundary conditions for the numerical simulation were derived from the experimental testing where the inlet temperature was set to 1023 K. A polyhedral unstructured mesh made the meshing of internal coolant plenums including the detailed supporting structures possible. The simulation demonstrated that the highest temperature at the blade leading edge was 117 K lower than the uncooled turbine. The coolant mass flow required by turbine was 2.5% of the mainstream flow to achieve this temperature drop. The inertia of the turbine was also reduced by 20% due to the removal of mass required for the internal coolant plenums. The fluid fields in both the coolant channels and downstream of the cooled rotor were analyzed to determine the aerodynamic influence on the temperature distribution. Furthermore, the solid stress distribution inside the rotor was analyzed using Finite Element Analysis (FEA) coupled with the CFD results.

scholarly journals A topology optimisation for three-dimensional acoustics with the level set method and the fast multipole boundary element method

2014 ◽  
Vol 1 (4) ◽  
pp. CM0039-CM0039 ◽  
Author(s):  
Hiroshi ISAKARI ◽  
Kohei KURIYAMA ◽  
Shinya HARADA ◽  
Takayuki YAMADA ◽  
Toru TAKAHASHI ◽  
...  
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Level Set Method ◽  
Level Set ◽  
Three Dimensional ◽  
Topology Optimisation ◽  
Fast Multipole ◽  
Element Method
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