scholarly journals A systems approach to shape and topology optimisation of mechanical structures

2012 ◽  
Author(s):  
K. Fiedler ◽  
B. F. Rolfe ◽  
A. Asgari ◽  
T. de Souza
Keyword(s):  
Systems Approach ◽  
Topology Optimisation ◽  
And Topology

Development of a patient-specific immobilisation facemask for radiation therapy using additive manufacturing, pressure sensors and topology optimisation

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Amirhossein Asfia ◽  
James I. Novak ◽  
Bernard Rolfe ◽  
Tomas Kron
Keyword(s):  
Additive Manufacturing ◽  
Head Movement ◽  
Pressure Sensors ◽  
Sensor Data ◽  
Patient Specific ◽  
Topology Optimisation ◽  
Content Type ◽  
Fused Deposition ◽  
And Topology ◽  
Mask Design

Purpose Radiotherapy relies on the delivery of radiation to cancer cells with millimetre accuracy, and immobilisation of patients is essential to minimise unwanted damage to surrounding healthy cells due to patient movement. Traditional thermoformed face masks can be uncomfortable and stressful for patients and may not be accurately fitted. The purpose of this study was to use 3D scanning and additive manufacturing to digitise this workflow and improve patient comfort and treatment outcomes. Design/methodology/approach The head of a volunteer was scanned using an Artec Leo optical scanner (Artec, Luxembourg) and ANSYS (Ansys, Canonsburg, USA) software was used to make two 3D models of the mask: one with a nose bridge and one open as would be used with optical surface guidance. Data based on measurements from ten pressure sensors around the face was used to perform topology optimisation, with the best designs 3D printed using fused deposition modelling (FDM) and tested on the volunteer with embedded pressure sensors. Findings The two facemasks proved to be significantly different in terms of restricting head movement inside the masks. The optimised mask with a nose bridge effectively restricted head movement in roll and yaw orientations and exhibited minimal deformation as compared to the open mask design and the thermoformed mask. Originality/value The proposed workflow allows customisation of masks for radiotherapy immobilisation using additive manufacturing and topology optimisation based on collected pressure sensor data. In the future, sensors could be embedded in masks to provide real-time feedback to clinicians during treatment.

A shape and topology optimisation of electro-magnetic devices using the level set method

2018 ◽  
Vol 2018.31 (0) ◽  
pp. 308
Author(s):  
Kei MATSUSHIMA ◽  
Hiroshi ISAKARI ◽  
Toru TAKAHASHI ◽  
Toshiro MATSUMOTO
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Topology Optimisation ◽  
Magnetic Devices ◽  
And Topology ◽  
Electro Magnetic

A shape and topology optimisation of cloaking devices using configuration expression with the level set method

2018 ◽  
Vol 2018.67 (0) ◽  
pp. 501
Author(s):  
Kenta NAKAMOTO ◽  
Hiroshi ISAKARI ◽  
Toru TAKAHASHI ◽  
Toshiro MATSUMOTO
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Topology Optimisation ◽  
And Topology

Asymptotic expansion homogenisation and topology optimisation of cellular materials

2016 ◽  
Vol 28 (1) ◽  
pp. 40-46
Author(s):  
J. Dias-de-Oliveira ◽  
J. Pinho-da-Cruz ◽  
F. Teixeira-Dias
Keyword(s):  
Asymptotic Expansion ◽  
Cellular Materials ◽  
Topology Optimisation ◽  
And Topology

scholarly journals A hybrid method for shape and topology optimization in fluid mechanics

2019 ◽  
Author(s):  
Γεώργιος Καρπούζας
Keyword(s):  
Hybrid Method ◽  
The Other ◽  
Adjoint Equations ◽  
Internal Boundary ◽  
Topology Optimisation ◽  
Full Potential ◽  
Computational Domain ◽  
And Topology ◽  
Moving Cylinder ◽  
Wide Range

Adjoint optimisation is an exciting and fast growing research and application field in Computational Fluid Dynamics (CFD). It is widely used in shape, topology, flow control, error estimation, inverse, and robust design optimisation problems. The present thesis focuses on the first two categories: shape and topology optimisation. The two methods in question historically have very distinct characteristics and, as a result of these differences, the usage of one or the other method may have clear advantages and/or disadvantages in the context of individual optimization problems. The method chosen for a specific optimisation problem can, thus, have distinct advantages over the other in terms of how much improvement in design can be practically achieved. Our ultimate aim is to overcome, to a significant extent, these limitations by hybridising the two methods.To achieve this end, it is necessary to understand both the strengths and weaknesses of the available methodologies and how they arise in the context of the optimisation system. First, the accuracy issue regarding the modelling of the solid regions in porositybased topology optimisation is examined and it is found that many of the problems relate to the lack of an exact interface between the solid and fluid regions. Extending the topology optimisation framework to incorporate a welldefined interface, using the levelset method, alleviates some of these problems. However, the correct implementation of nearwall turbulence modelling remains an issue. Using the volumeaveraged total pressure losses as an objective function, levelset based topology optimisation is used to optimize the design of: i) a rightangled duct; ii) a heating, ventilation, and airconditioning (HVAC) duct; iii) the inlet and outlet ducts of a gearpump; and iv) a cold air intake system (CAIS) of a car.In the second part of this thesis, a novel method called Generalised Internal Boundary (GIB) is derived, implemented and validated, which allows for the imposition of exact boundary conditions internal to the computational domain. This is achieved without changing the topology/connectivity of the computational mesh, which dramatically improves the algorithms’ performance.To realise their full potential, the new boundaries must be able to physically deform and move. However, transitioning elements over the interface from solid to fluid (and vice versa) introduces discontinuities in the timehistory of the solution fields. These timehistories are critical to the solution of governing equations incorporating timederivatives. Thus, it is necessary to reconstruct the old time values of the fields so they appear smooth, yet conservative, from the perspective of the conservation equations. In this context, an ArbitraryLagrangianEulerian (ALE) framework that incorporates the conservative reconstruction of old timefield values in the presence of strongly discontinuous cell transition events is proposed. The results of the proposed method were compared against the bodyfitted approach of the flow around a moving cylinder and validated against experimental data from a closing butterfly valve.With the capabilities of the GIB method in hand, a new adjoint optimization method is considered and a hybrid between shape and topology approaches is proposed. This has the accuracy of shape optimisation as the boundary it produces is exact in all respects but, at the same time (and similar to topology optimisation), it has the freedom to make arbitrarily large changes in the design. Thus, the new method elegantly does away with most of the drawbacks inherent in both shape and topology optimisation and as a result, provides a universal solution to a larger subset of adjoint optimisation problems. The proposed hybrid shapetopology optimisation method is used to optimise the design of: i) a rightangled duct; and ii) a manifold with two outlets.Although not central to the main theme, some improvements are proposed related to the solution of the primal and adjoint equations in terms of computational cost and robustness. These works supplement the development of the hybrid adjoint optimisation method as they enhance the solution of the adjoint equation system. Three main contributions are identified:– Instabilities caused by the Adjoint Transpose Convection (ATC) term are first highlighted and, then, methods to tackle the problem are proposed.– The accuracy of the pressure gradient adjacent to the solid walls plays an important role in the solution of the flow close to the wall and has a large impact on the convergence of the adjoint equations. A more accurate treatment of this term is shown to have significant benefits in terms of accuracy and stability.– A blocksolver is developed to solve the linear adjoint system implicitly, dramatically improving time to solution and reducing ATCrelated issues. To demonstrate the performance of the blocksolver, sensitivity maps are computed over the Ahmedbody and the DrivAer car geometries using the blocksolver and segregated approach. It is shown that the blocksolver provides orders of magnitude better performance against the segregated approach in both cases.The effectiveness of the new hybrid method and other enhancements is clearly demonstrated in the context of a practically relevant application. Specifically, (i) the GIB is shown to be a powerful new tool for solving a range of complex moving boundary problems; and (ii) adjoint optimisation employing the hybrid shapetopology method is found to be an efficient tool for automated generative design across a wide range of problem categories.

A shape and topology optimisation using a boundary expression based on the level set method

2018 ◽  
Vol 2018 (0) ◽  
pp. F121004
Author(s):  
Kenta NAKAMOTO ◽  
Hiroshi ISAKARI ◽  
Toru TAKAHASHI ◽  
Toshiro MATSUMOTO
Keyword(s):  
Level Set Method ◽  
Level Set ◽  
Topology Optimisation ◽  
And Topology
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