Journal articles: 'Topological Optimisation'

1

Almeida, Henrique A., and Paulo J. Bártolo. "Topological Optimisation of Scaffolds for Tissue Engineering." Procedia Engineering 59 (2013): 298–306. http://dx.doi.org/10.1016/j.proeng.2013.05.125.

Full text

APA, Harvard, Vancouver, ISO, and other styles

2

Almeida, Henrique de Amorim, and Paulo Jorge da Silva Bártolo. "Virtual topological optimisation of scaffolds for rapid prototyping." Medical Engineering & Physics 32, no. 7 (September 2010): 775–82. http://dx.doi.org/10.1016/j.medengphy.2010.05.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Xie (Mike), Yi Min, Zhi Hao Zuo, Xiaodong Huang, Tim Black, and Peter Felicetti. "Application of Topological Optimisation Technology to Bridge Design." Structural Engineering International 24, no. 2 (May 2014): 185–91. http://dx.doi.org/10.2749/101686614x13830790993366.

Full text

APA, Harvard, Vancouver, ISO, and other styles

4

Xu, Yihong, and Chuanxi Zhu. "On super efficiency in set-valued optimisation in locally convex spaces." Bulletin of the Australian Mathematical Society 71, no. 2 (April 2005): 183–92. http://dx.doi.org/10.1017/s0004972700038168.

Full text

Abstract:

The set-valued optimisation problem with constraints is considered in the sense of super efficiency in locally convex linear topological spaces. Under the assumption of nearly cone-subconvexlikeness, by applying the separation theorem for convex sets, Kuhn-Tucker and Lagrange necessary conditions for the set-valued optimisation problem to attain its super efficient solutions are obtained. Also, Kuhn-Tucker and Lagrange sufficient conditions are derived. Finally two kinds of unconstrained programs equivalent to set-valued optimisation problems are established.

APA, Harvard, Vancouver, ISO, and other styles

5

Baublys, Adolfas. "IMPROVEMENT OF FREIGHT TRANSPORT TECHNOLOGIES AND IMPLEMENTATION OF NEW TECHNOLOGIES." TRANSPORT 18, no. 5 (October 31, 2003): 193–97. http://dx.doi.org/10.3846/16483840.2003.10414096.

Full text

Abstract:

The synthesis of regional (urban) road transport freight system topological structure enables the assessment of impact exercised by various structural characteristics on the functioning of the system. For this reason the quality of project solutions in the stage of system structural synthesis increases. Models of optimisation and simulation (included into the simulation procedure of optimisation of topological structure) have other possibilities as well. For instance, simulation model enables the solution of such various objectives of functional analysis of systems as, for example, the efficiency comparison analysis of stability of structure undergoing the changes of meanings of system parameters, the analysis of managing impacts of various types, loading technologies, etc.

APA, Harvard, Vancouver, ISO, and other styles

6

Billenstein, D., C. Dinkel, and F. Rieg. "Automated Topological Clustering of Design Proposals in Structural Optimisation." International Journal of Simulation Modelling 17, no. 4 (December 15, 2018): 657–66. http://dx.doi.org/10.2507/ijsimm17(4)454.

Full text

APA, Harvard, Vancouver, ISO, and other styles

7

KAMAHORI, Mizuki, Hiroshi ISAKARI, Toru TAKAHASHI, and Toshiro MATSUMOTO. "A structural optimisation using shape and topological derivatives simultaneously." Proceedings of OPTIS 2018.13 (2018): 111. http://dx.doi.org/10.1299/jsmeoptis.2018.13.111.

Full text

APA, Harvard, Vancouver, ISO, and other styles

8

Matamala, Adelio R., and Ernesto Estrada. "Generalised topological indices: Optimisation methodology and physico-chemical interpretation." Chemical Physics Letters 410, no. 4-6 (July 2005): 343–47. http://dx.doi.org/10.1016/j.cplett.2005.05.096.

Full text

APA, Harvard, Vancouver, ISO, and other styles

9

YOSHIMITSU, Ichi, Hiroshi ISAKARI, Toru TAKAHASHI, and Toshiro MATSUMOTO. "A topological optimisation for 3D elastostatic problem with boundary element method." Proceedings of The Computational Mechanics Conference 2016.29 (2016): 4_115. http://dx.doi.org/10.1299/jsmecmd.2016.29.4_115.

Full text

APA, Harvard, Vancouver, ISO, and other styles

10

Skworcow, P., D. Paluszczyszyn, and B. Ulanicki. "Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems." Drinking Water Engineering and Science Discussions 7, no. 1 (February 10, 2014): 121–49. http://dx.doi.org/10.5194/dwesd-7-121-2014.

Full text

Abstract:

Abstract. This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in GAMS language from a hydraulic model in EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for variety of requirements.

APA, Harvard, Vancouver, ISO, and other styles

11

Kalliorinne, Kalle, Francesc Pérez-Ràfols, John Fabricius, and Andreas Almqvist. "Application of topological optimisation methodology to infinitely wide slider bearings operating under compressible flow." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 234, no. 7 (February 2, 2020): 1035–50. http://dx.doi.org/10.1177/1350650120901907.

Full text

Abstract:

It has been over a century since the interest in inventing the optimal topology for bearings arose. A significant achievement was published by Lord Rayleigh, who found the step-bearing geometry which maximise the load-carrying capacity when the classical Reynolds equation is used to model thin film flow of an iso-viscous and incompressible fluid. Since then, new optimisation methods considering some variants of governing equations for finding the best possible bearings have surfaced, one of which will be presented in this paper. Here, two different formulations for compressible flow, i.e. ideal gas and constant bulk modulus compressibility, as well as the classical Reynolds formulation will be used in combination with the method of moving asymptotes for topological optimisation. All three of these problem formulations provide us with unique geometries, which either maximise the load-carrying capacity or minimise friction, for fluids with a wide variety of compressibility.

APA, Harvard, Vancouver, ISO, and other styles

12

Skworcow, P., D. Paluszczyszyn, and B. Ulanicki. "Pump schedules optimisation with pressure aspects in complex large-scale water distribution systems." Drinking Water Engineering and Science 7, no. 1 (June 16, 2014): 53–62. http://dx.doi.org/10.5194/dwes-7-53-2014.

Full text

Abstract:

Abstract. This paper considers optimisation of pump and valve schedules in complex large-scale water distribution networks (WDN), taking into account pressure aspects such as minimum service pressure and pressure-dependent leakage. An optimisation model is automatically generated in the GAMS language from a hydraulic model in the EPANET format and from additional files describing operational constraints, electricity tariffs and pump station configurations. The paper describes in details how each hydraulic component is modelled. To reduce the size of the optimisation problem the full hydraulic model is simplified using module reduction algorithm, while retaining the nonlinear characteristics of the model. Subsequently, a nonlinear programming solver CONOPT is used to solve the optimisation model, which is in the form of Nonlinear Programming with Discontinuous Derivatives (DNLP). The results produced by CONOPT are processed further by heuristic algorithms to generate integer solution. The proposed approached was tested on a large-scale WDN model provided in the EPANET format. The considered WDN included complex structures and interactions between pump stations. Solving of several scenarios considering different horizons, time steps, operational constraints, demand levels and topological changes demonstrated ability of the approach to automatically generate and solve optimisation problems for a variety of requirements.

APA, Harvard, Vancouver, ISO, and other styles

13

Todinov, M. T. "Risk-based reliability allocation and topological optimisation based on minimising the total cost." International Journal of Reliability and Safety 1, no. 4 (2007): 489. http://dx.doi.org/10.1504/ijrs.2007.016261.

Full text

APA, Harvard, Vancouver, ISO, and other styles

14

Almeida, Henrique A., and Paulo J. Bártolo. "Combined Elastic and Shear Stress Solicitations for Topological Optimisation of Micro-CT Based Scaffolds." Procedia Engineering 110 (2015): 159–66. http://dx.doi.org/10.1016/j.proeng.2015.07.024.

Full text

APA, Harvard, Vancouver, ISO, and other styles

15

Zhang, Junyuan, Zhongyu Li, Qiang Fang, and Chao Chen. "Topological optimisation design of passenger car seat backrest frame based on multiple-loading conditions." International Journal of Crashworthiness 25, no. 5 (June 28, 2019): 581–90. http://dx.doi.org/10.1080/13588265.2019.1634355.

Full text

APA, Harvard, Vancouver, ISO, and other styles

16

Gao, Xingjun, Riccardo Caivano, Andrea Tridello, Giorgio Chiandussi, Haitao Ma, Davide Paolino, and Filippo Berto. "Innovative formulation for topological fatigue optimisation based on material defects distribution and TopFat algorithm." International Journal of Fatigue 147 (June 2021): 106176. http://dx.doi.org/10.1016/j.ijfatigue.2021.106176.

Full text

APA, Harvard, Vancouver, ISO, and other styles

17

Finney, Mark A., Rob C. Seli, Charles W. McHugh, Alan A. Ager, Bernhard Bahro, and James K. Agee. "Simulation of long-term landscape-level fuel treatment effects on large wildfires." International Journal of Wildland Fire 16, no. 6 (2007): 712. http://dx.doi.org/10.1071/wf06064.

Full text

Abstract:

A simulation system was developed to explore how fuel treatments placed in topologically random and optimal spatial patterns affect the growth and behaviour of large fires when implemented at different rates over the course of five decades. The system consisted of a forest and fuel dynamics simulation module (Forest Vegetation Simulator, FVS), logic for deriving fuel model dynamics from FVS output, a spatial fuel treatment optimisation program, and a spatial fire growth and behaviour model to evaluate the performance of the treatments in modifying large fire growth. Simulations were performed for three study areas: Sanders County in western Montana, the Stanislaus National Forest in California, and the Blue Mountains in south-eastern Washington. For different spatial treatment strategies, the results illustrated that the rate of fuel treatment (percentage of land area treated per decade) competes against the rates of fuel recovery to determine how fuel treatments contribute to multidecade cumulative impacts on the response variables. Using fuel treatment prescriptions that simulate thinning and prescribed burning, fuel treatment arrangements that are optimal in disrupting the growth of large fires require at least 1 to 2% of the landscape to be treated each year. Randomly arranged units with the same treatment prescriptions require about twice that rate to produce the same fire growth reduction. The results also show that the topological fuel treatment optimisation tends to balance maintenance of previous units with treatment of new units. For example, with 2% landscape treatment annually, fewer than 5% of the units received three or more treatments in five decades with most being treated only once or twice and ~35% remaining untreated after five decades.

APA, Harvard, Vancouver, ISO, and other styles

18

Kang, Sungwook, J. Choi, and Sengkwan Choi. "Mechanism of Heat Transfer through Porous Media of Inorganic Intumescent Coating in Cone Calorimeter Testing." Polymers 11, no. 2 (January 29, 2019): 221. http://dx.doi.org/10.3390/polym11020221.

Full text

Abstract:

This work discusses the heat transfer process through a particular form of porous media: an inorganic-based intumescent coating in full-expansion state. Although the thermal mechanism in porous media has been vigorously studied for polymeric/ceramic/metallic foams, less information is available on its application with intumescent-type polymers. This examination demonstrates the procedure of (1) the optimisation of the coating’s internal multicellular structure for numerical modelling, based on topological analyses; (2) the finite element simulation for the coating-sample tested with cone calorimetry; and (3) the quantitative evaluation of the thermal insulation performance of its porous structure by adopting effective thermal conductivity. The modelling technique was verified using measurable data from the cone calorimeter tests. Consistent agreement between the numerical predictions and experimental measurements was achieved over the whole steel-substrate temperature history, based on the clarified thermal boundaries of the specimen and modelling of the combined conduction-radiation transfer. This numerical approach exhibits the impacts of porosity, pore-size, and external thermal load on the medium’s performance, as well as the individual contributions of the component heat transfer modes to the overall process. The full understanding of this thermal mechanism can contribute to the enhancement and optimisation of the thermal insulation performance of a porous-type refractory polymer.

APA, Harvard, Vancouver, ISO, and other styles

19

Santhanakrishnan, Mani Sekaran, Timothy Tilford, and Christopher Bailey. "Performance assessment of density and level-set topology optimisation methods for three dimensional heat sink design." Journal of Algorithms & Computational Technology 12, no. 3 (June 9, 2018): 273–87. http://dx.doi.org/10.1177/1748301818779019.

Full text

Abstract:

In this paper, two most prevalent topological optimisation approaches namely Density and Level set method are applied to a three dimensional heat sink design problem. The relative performance of the two approaches is compared in terms of design quality, robustness and computational speed. The work is original as for the first time it demonstrates the relative advantages and disadvantages for each method when applied to a practical engineering problem. It is additionally novel in that it presents the design of a convectively cooled heat sink by solving full thermo-fluid equations for two different solid-fluid material sets. Further, results are validated using a separate computational fluid dynamics study with the optimised designs are compared against a standard pin-fin-based heat sink design. The results show that the Density method demonstrates better performance in terms of robustness and computational speed, while Level-set method yields a better quality design in terms of final objective value.

APA, Harvard, Vancouver, ISO, and other styles

20

Djami, Aslain Brisco Ngnassi, and Wolfgang Nzie. "Analyse Conceptuelle Et Optimisation De La Fiabilité Des Systèmes : Cas D’une Unité De Production De Farines Des Nourrissons." European Scientific Journal, ESJ 14, no. 24 (August 31, 2018): 283. http://dx.doi.org/10.19044/esj.2018.v14n24p283.

Full text

Abstract:

The purpose of this article is to propose an approach to analyse and optimize the topology of reliability in the design of mechanical systems. The application is made on a chain of production of infant flours. Indeed, the systems that we design are more and more complex and must be realized at reduced costs. These systems are "multi-domains" because many trades come into play. High reliability for complex topology systems is required. Thus, we present a methodology for the analysis of reliability in the design process that groups models based on diagrams. Finally, to optimize the topological configuration and the reliability of the system, the so-called "robust design" method coupled with an appropriate algorithm is deployed. The expected result is: the proposal of a methodology for optimizing the topology and the reliability of the systems.

APA, Harvard, Vancouver, ISO, and other styles

21

Silva, Tiago, Afonso Gregório, Filipe Silva, José Xavier, Ana Reis, Pedro Rosa, and Abílio de Jesus. "Numerical-Experimental Plastic-Damage Characterisation of Additively Manufactured 18Ni300 Maraging Steel by Means of Multiaxial Double-Notched Specimens." Journal of Manufacturing and Materials Processing 5, no. 3 (August 2, 2021): 84. http://dx.doi.org/10.3390/jmmp5030084.

Full text

Abstract:

Additive manufacturing (AM) has become a viable option for producing structural parts with a high degree of geometrical complexity. Despite such trend, accurate material properties, under diversified testing conditions, are scarce or practically non-existent for the most recent additively manufactured (AMed) materials. Such data gap may compromise component performance design, through numerical simulation, especially enhanced by topological optimisation of AMed components. This study aimed at a comprehensive characterisation of laser powder bed fusion as-built 18Ni300 maraging steel and its systematic comparison to the conventional counterpart. Multiaxial double-notched specimens demonstrated a successful depiction of both plastic and damage behaviour under different stress states. Tensile specimens with distinct notch configurations were also used for high stress triaxiality range characterisation. This study demonstrates that the multiaxial double-notched specimens constitute a viable option towards the inverse plastic behaviour calibration of high-strength additively manufactured steels in distinct state of stress conditions. AMed maraging steel exhibited higher strength and lower ductility than the conventional material.

APA, Harvard, Vancouver, ISO, and other styles

22

HANADA, Moemi, Hiroshi ISAKARI, Toru TAKAHASHI, and Toshiro MATSUMOTO. "A Discussion on the Topological Derivative in 2D Acoustic-viscoelastic Field for a Topology Optimisation for a Sound-absorbing Material." Proceedings of Conference of Tokai Branch 2017.66 (2017): 514. http://dx.doi.org/10.1299/jsmetokai.2017.66.514.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Panigrahi, Niranjan, and Pabitra Mohan Khilar. "Optimal topological balancing strategy for performance optimisation of consensus-based clock synchronisation protocols in wireless sensor networks: a genetic algorithm-based approach." IET Wireless Sensor Systems 4, no. 4 (December 1, 2014): 213–22. http://dx.doi.org/10.1049/iet-wss.2014.0063.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Rokstad, Marius Møller. "Optimisation of Fixed-Outlet and Flow-Modulated Pressure Reduction Measures in Looped Water Distribution Networks Constrained by Fire-Fighting Capacity Requirements." International Journal of Environmental Research and Public Health 18, no. 13 (July 2, 2021): 7088. http://dx.doi.org/10.3390/ijerph18137088.

Full text

Abstract:

Pressure management is a pivotal component when reducing leakages from water distribution networks, and can be achieved by sub-dividing existing networks into partitions where the pressure can be reduced effectively. There is a need to develop methods that aid in the identification of cost-effective partitions for pressure reduction, while simultaneously verifying that the topological changes entailed in these solutions do not compromise reliability and (fire-fighting) capacity requirements, especially in systems where the capacity is ensured through looped networks. This paper presents a method that can be used to this end, in which a novel combination of hydraulic simulations and graph theory is used to determine the maximal potential for (dynamic and static) pressure reduction, and this is used as a constraint for multi-objective optimization of pressure reduction measures. Trondheim, Norway, has been used as a case study area, and it is demonstrated how the developed method aids in the process of achieving leakage reduction in Trondheim. The results for Trondheim show that an economically optimal solution for pressure management is predicted to lead to a reduction from 28 to 22% water loss volume, and furthermore that effective pressure management will rely heavily on active (dynamic) regulation in this particular system.

APA, Harvard, Vancouver, ISO, and other styles

25

Trofimova, Larysa. "Modeling and Optimization of Technology and Physics-Mechanical Properties of Composite Materials." Key Engineering Materials 864 (September 2020): 59–65. http://dx.doi.org/10.4028/www.scientific.net/kem.864.59.

Full text

Abstract:

To this day, there is a large volume collected of the results of experimental studies on structure changes in various dispersions serving as base for production of most construction materials. The analysis of collected information revealed that there is an entire category of stick-slip phenomena, the case history of which is represented by N-and S-type inflections on rheological, kinetic and other curves. We should emphasis that the view of such non-trivial charts is alike with geometry of standard curves of standard conditions. And this alikeness predetermines the possibility of applying topological models of «fold» and «ruffle» types for studying various abnormal effects. We must also note that besides N- and S-types there is a range of other characteristics («flags») pointing to applicability of the methods of catastrophe theory to studying certain processes initiating the apparition of interruptions in system development. Recognition of above-mentioned particularities allows determining the fact and type of catastrophe, the standardised structure of which facilitates finding strict patterns and thus defines directions of optimisation of various situations of research and practical nature. This work shows that pieces of evidence and consistent patters are reliably interpreted within the framework of the proposed concept.

APA, Harvard, Vancouver, ISO, and other styles

26

McEwen, Iain, David Cooper, Jay Warnett, Nadia Kourra, Mark Williams, and Gregory Gibbons. "Design & Manufacture of a High-Performance Bicycle Crank by Additive Manufacturing." Applied Sciences 8, no. 8 (August 13, 2018): 1360. http://dx.doi.org/10.3390/app8081360.

Full text

Abstract:

A new practical workflow for the laser Powder Bed Fusion (PBF) process, incorporating topological design, mechanical simulation, manufacture, and validation by computed tomography is presented, uniquely applied to a consumer product (crank for a high-performance racing bicycle), an approach that is tangible and adoptable by industry. The lightweight crank design was realised using topology optimisation software, developing an optimal design iteratively from a simple primitive within a design space and with the addition of load boundary conditions (obtained from prior biomechanical crank force–angle models) and constraints. Parametric design modification was necessary to meet the Design for Additive Manufacturing (DfAM) considerations for PBF to reduce build time, material usage, and post-processing labour. Static testing proved performance close to current market leaders with the PBF manufactured crank found to be stiffer than the benchmark design (static load deflection of 7.0 ± 0.5 mm c.f. 7.67 mm for a Shimano crank at a competitive mass (155 g vs. 175 g). Dynamic mechanical performance proved inadequate, with failure at 2495 ± 125 cycles; the failure mechanism was consistent in both its form and location. This research is valuable and novel as it demonstrates a complete workflow from design, manufacture, post-treatment, and validation of a highly loaded PBF manufactured consumer component, offering practitioners a validated approach to the application of PBF for components with application outside of the accepted sectors (aerospace, biomedical, autosports, space, and power generation).

APA, Harvard, Vancouver, ISO, and other styles

27

Guilbert, E., S. Jutras, and T. Badard. "THALWEG DETECTION FOR RIVER NETWORK CARTOGRAPHY IN FOREST FROM HIGH-RESOLUTION LIDAR DATA." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLII-4 (September 19, 2018): 241–47. http://dx.doi.org/10.5194/isprs-archives-xlii-4-241-2018.

Full text

Abstract:

<p><strong>Abstract.</strong> This paper addresses the problem of extracting the drainage network in forested areas. A precise description of the drainage network including intermittent streams is required for the planning of logging operations and environmental conservation. LiDAR provides now high-resolution point clouds from which the terrain is modelled and the drainage extracted but it also brings some challenges for traditional approaches. First, the raster DTM is interpolated from LiDAR ground points and has to be split in tiles for processing, adding approximations. Second, drainage enforcement techniques alter the terrain and rely on parameters difficult to fix and limiting the optimisation of the process. In this context, we discuss a new approach aiming at: (1) Designing a data structure to model the terrain with a Triangulated Irregular Network in order to avoid interpolation. This data structure must enable the distribution of data and processes across several nodes in Big data architectures and eventually, the processing of complete watersheds with no tiling. (2) Modelling the river network through thalwegs and avoiding the filling and breaching operations. Thalweg detection is more robust, removing the need for filling and breaching. However, it yields a very dense network requiring a simplification step. Combining this model and the architecture will enable the design and modelling of a new tool for river network computation directly from LiDAR ground points. In this paper, we mainly discuss the second point and propose to model the drainage by a network of thalwegs computed from the terrain. Thalwegs are extracted from the surface network, a topological structure formed of peaks, pits and saddles as vertices and ridges and thalwegs as vertices. We present preliminary results comparing the thalweg network and the drainage network.</p>

APA, Harvard, Vancouver, ISO, and other styles

28

Yin, Ge, Xiao Xiao, and Fehmi Cirak. "Topologically robust CAD model generation for structural optimisation." Computer Methods in Applied Mechanics and Engineering 369 (September 2020): 113102. http://dx.doi.org/10.1016/j.cma.2020.113102.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Matsika, Emmanuel, Conor O’Neill, Marzio Grasso, and Antonio De Iorio. "Selection and ranking of the main beam geometry of a freight wagon for lightweighting." Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit 232, no. 2 (November 16, 2016): 495–513. http://dx.doi.org/10.1177/0954409716677075.

Full text

Abstract:

The traditional freight wagons employ I-beam sections as the main load-bearing structures. The primary loads they carry are vertical (from loading units) and axial (from train traction and buffers). Ease of manufacturing has played an important role in the selection of the I-beam for this role. However, with lightweighting increasingly becoming an important design objective, an evaluation needs to be done to assess if there are other existing or new section profiles (geometry) that would carry the same operational loads but are lighter. This paper presents an evaluation of 24 section profiles for their ability to take the operational loads of freight wagons. The profiles are divided into two categories, namely ‘conventional – made by wagon manufacturers (including the I-beam)’ and ‘pre-fabricated’ sections. For ranking purposes, the primary design objectives or key performance indicators were bending stress, associated deflection and buckling load. Subsequently, this was treated as a multi-criteria decision-making process. The loading conditions were applied as prescribed by the EU standard EN 12663-2. To carry out structural analysis, finite element analysis was implemented using ANSYS software. To determine the validity of the finite element analysis results, correlation analysis was done with respect to beam theory. Parameters considered were: maximum stress, deflection, second moment of area, thickness, bending stiffness and flexural rigidity. The paper discusses the impreciseness related to the use of beam theory since the local stiffness of the beam is neglected leading to an inaccurate estimation of the buckling load and the vertical displacement. Even more complicated can be the estimation of the maximum stress to be used for comparison when features such as spot welds are present. The nominal stress values computed by means of Navier equation lead to an inaccurate value of the stress since it neglects the variations in the local stiffness, which can lead to an increase in the bending stress values. The main objective of the paper is the applicability of particular section profiles to the railway field with the aim of lightweighting the main structure. Sections commonly adopted in civil applications have also been investigated to understand the stiffness and strength under railway service loads. The common approach reported in literature so far makes use either of the beam theory or topological finite element approach to determine the optimised shape under the action of the simplified loading conditions. Although the previous approaches seem to be more general, the assumptions made affect the optimisation process since the stress state differs from that attained under the actual service load in the real structure. In this paper, the use of complex shape cross sections and detailed finite element models allows to take account of the real behaviour in terms of stiffness distribution and local stress effects due to manufacturing features like welds. The structural assessment carried out with the detailed models also allows for the proper comparison among the considered sections. Analysis of the results showed that three out of the 24 section profiles have the highest potential to be fitted as the main load-bearing beams for freight wagons, with the pre-fabricated Z-section being the optimum of the three.

APA, Harvard, Vancouver, ISO, and other styles

30

Silva, Miguel R., João A. Dias-de-Oliveira, António M. Pereira, Nuno M. Alves, Álvaro M. Sampaio, and António J. Pontes. "Design of Kinematic Connectors for Microstructured Materials Produced by Additive Manufacturing." Polymers 13, no. 9 (May 6, 2021): 1500. http://dx.doi.org/10.3390/polym13091500.

Full text

Abstract:

The main characteristic of materials with a functional gradient is the progressive composition or the structure variation across its geometry. This results in the properties variation in one or more specific directions, according to the functional application requirements. Cellular structure flexibility in tailoring properties is employed frequently to design functionally-graded materials. Topology optimisation methods are powerful tools to functionally graded materials design with cellular structure geometry, although continuity between adjacent unit-cells in gradient directions remains a restriction. It is mandatory to attain a manufacturable part to guarantee the connectedness between adjoining microstructures, namely by ensuring that the solid regions on the microstructure’s borders i.e., kinematic connectors) match the neighboring cells that share the same boundary. This study assesses the kinematic connectors generated by imposing local density restrictions in the initial design domain (i.e., nucleation) between topologically optimised representative unit-cells. Several kinematic connector examples are presented for two representatives unit-cells topology optimised for maximum bulk and shear moduli with different volume fractions restrictions and graduated Young’s modulus. Experimental mechanical tests (compression) were performed, and comparison studies were carried out between experimental and numerical Young’s modulus. The results for the single maximum bulk for the mean values for experimental compressive Young’s modulus (Ex¯) with 60%Vf show a deviation of 9.15%. The single maximum shear for the experimental compressive Young’s modulus mean values (Ex¯) with 60%Vf, exhibit a deviation of 11.73%. For graded structures, the experimental mean values of compressive Young’s moduli (Ex¯), compared with predicted total Young’s moduli (ESe), show a deviation of 6.96 for the bulk graded structure. The main results show that the single type representative unit-cell experimental Young’s modulus with higher volume fraction presents a minor deviation compared with homogenized data. Both (i.e., bulk and shear moduli) graded microstructures show continuity between adjacent cells. The proposed method proved to be suitable for generating kinematic connections for the design of shear and bulk graduated microstructured materials.

APA, Harvard, Vancouver, ISO, and other styles

31

Nikulshin, Vladimir, and Viktoria Von Zedtwitz. "OPTIMAL DISIGN OF ENERGY SUPPLY NETS ON GRAPHS." International Journal of Computing, August 1, 2014, 68–73. http://dx.doi.org/10.47839/ijc.6.3.453.

Full text

Abstract:

In the design and operation of energy intensive systems, the possibility of improving the system’s efficiency is very important to explore. The main way of improving efficiency is through optimisation. This paper describes the application of exergy topological models and, in particular, the graph of thermoeconomical expenditure for thermoeconomical optimal design s of circled nets for energy supply (CNES). The questions of thermoeconomical optimisation of CNES, as well as suggested modelling algorithms, are illustrated in the numerical example of the optimisation of a energy supply system for a city with seven regions of energy consumption.

APA, Harvard, Vancouver, ISO, and other styles

32

Kalliorinne, Kalle, Roland Larsson, and Andreas Almqvist. "Application of topological optimisation methodology to hydrodynamic thrust bearings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, November 11, 2020, 135065012097259. http://dx.doi.org/10.1177/1350650120972594.

Full text

Abstract:

The bearing geometry has a big impact on the performance of a hydrodynamic thrust bearing. For this reason, shape optimisation of the bearing surface has been carried out for some time, with Lord Rayleigh’s early publication dated back to 1918. There are several recent results e.g. optimal bearing geometries that maximise the load carrying capacity for hydrodynamic thrust bearings. Currently, many engineers are making an effort to include sustainability in their work, which increases the need for bearings with lower friction and higher load carrying capacity. Improving these two qualities will result in lower energy consumption and increase the lifetime of applications, which are outcomes that will contribute to a sustainable future. For this reason, there is a need to find geometries that have performance characteristics of as low coefficient of friction torque as possible. In this work, the topological optimisation method of moving asymptotes is employed to optimise bearing geometries with the objective of minimising the coefficient of friction torque. The results are both optimised bearing geometries that minimise the coefficient of friction torque and bearing geometries that maximise the load carrying capacity. The bearing geometries are of comparable aspect ratios to the ones uses in recent publications. The present article also covers minimisation of friction torque on ring bearing geometries, also known as thrust washers. The results are thrust washers with periodical geometries, where the number of periodical segments has a high impact on the geometrical outcome.

APA, Harvard, Vancouver, ISO, and other styles

33

Ladeira, Artur Hallack, and Amilton Rodrigues da Silva. "Strut-and-tie models obtained by way of topological optimisation." Proceedings of the Institution of Civil Engineers - Structures and Buildings, September 7, 2021, 1–12. http://dx.doi.org/10.1680/jstbu.20.00116.

Full text

APA, Harvard, Vancouver, ISO, and other styles

34

Kalliorinne, Kalle, and Andreas Almqvist. "Application of topological optimisation methodology to finitely wide slider bearings operating under incompressible flow." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology, May 23, 2020, 135065012091605. http://dx.doi.org/10.1177/1350650120916053.

Full text

Abstract:

The search for the optimal bearing geometry has been on for over a century. In a publication from 1918, Lord Rayleigh revealed the infinitely wide bearing geometry that maximises the load carrying capacity under incompressible flow, i.e. the Rayleigh step bearing. Four decades ago, Rohde, who continued on the same path, revealed the finitely wide bearing geometry that maximises the load carrying capacity, referred to as the Rayleigh-pocket bearing. Since then, the numerical results have been perfected with highly refined meshes, all converging to the same Rayleigh-pocket bearing. During recent years new methods for performing topology optimisations have been developed and one of those is the method of moving asymptotes, frequently used in the area of structural mechanics. In this work, the method of moving asymptotes is employed to find optimal bearing geometries under incompressible flow, for three different objectives. Among the results obtained are (i) show new bearing geometries that maximise the load carrying capacity, which performs better than the ones available, (ii) new bearing geometries minimising the coefficient of friction and (iii) new bearing geometries minimising the friction force for a given load carrying capacity are presented as well.

APA, Harvard, Vancouver, ISO, and other styles

35

Farmer, Benjamin L., Mark A. Beard, Oana Ghita, Robert Allen, and Ken E. Evans. "Assembly Strategies for Fully Aligned and Dispersed Morphology Controlled Carbon Nanotube Reinforced Composites Grown in Net-Shape." MRS Proceedings 1304 (2011). http://dx.doi.org/10.1557/opl.2011.602.

Full text

Abstract:

ABSTRACTLong carbon fibre polymer composites represent the state-of-the-art materials technology for high performance weight driven structures, such as airframes. Although a significant amount of optimisation remains to be done to fully exploit the benefits of long fibre composites, these materials are relatively speaking still very crude, when compared to what nature has achieved with wood or bone for example. Nanomaterials, and specifically carbon nanotubes (CNTs), have teased with their spectacular mechanical and physical properties in isolation. These headline properties have prompted much work into the manufacturing of composite materials using CNTs as reinforcements, but thus far, successful exploitation of these impressive properties has been modest. A gap remains before these materials represent a real competition to long carbon fibre composites, even though fairly modest applications such as CNTs as fillers for matrix toughening and imparting electrical functionality are showing some promise. In this paper a critique is made of various reinforcement approaches through the lens of ’nano-augmented, ’nano-engineered’ and ’nano-enabled’ categories as defined by Airbus. These approaches are compared to an analysis of nature’s ’baseline’. A new ’nano-enabled’ strategy for the growth of fully aligned and dispersed bulk CNT composite materials and structures, allowing for simultaneous multi-scalar morphological and topological optimisation, is described. This new strategy, analogous to nature’s approach, consists of the vapour phase growth of aligned forests of carbon nanotubes coupled to the environment of Additive Layer Manufacturing (ALM). Early feasibility results are presented and currently identified challenges to successful scale-up are discussed.

APA, Harvard, Vancouver, ISO, and other styles

36

"Papillary Trunk Bifurcation Angles as Major Determinants of Ocular Perfusion: A Cross-Sectional Study." Journal of Clinical Review & Case Reports 5, no. 6 (June 3, 2020). http://dx.doi.org/10.33140/jcrc.05.06.03.

Full text

Abstract:

Background: Notable work has been done by Cecile and Murray in as early as 1926, on the structural and topological aspects of vasculature based on the concept that blood vessel size and arrangement is such that it provides blood flow with minimum energy loss. In the theoretical analysis of arterial networks, the existence of geometric optimisation for enabling functional adequacy has long been suggested, but observational studies have not yet fully corroborated these theories. Data on branching or bifurcation angles of retinal microvasculature is not only insufficient but also inconclusive. Aim: Attending to this gap in information, we compared the central retinal artery (CRA) branching angles of known diabetics with healthy subjects and explored their possible role in determining the circulatory adequacy of human retina. Methods: This study was done on North Indian subjects attending retina clinics of prominent tertiary centers of north India during 2019 through 2020. Fundus images were acquired through convenience sampling from 860 consecutive eyes of 430 subjects. Fluorescein fundus angiography was followed up for diabetics. CRA branching angles from digitalized fundus photographs of known diabetics and healthy subjects was analyzed through semi-automated digital image management tool and the readings were clinically correlated to note the occurrence and severity of retinopathic perfusion defects was Results: We found marked differences between CRA branching angles among diabetics and healthy subjects and a significant correlation between branching anless and the occurrence and severity of retinopathic perfusion defects. Discussion and Conclusion: The orientation of retinal blood vessels on the fundus plane is not merely ‘a matter of chance’ in the anatomic chronicle of the human body; rather, it has biological heralds and functional consequences. Direction, branching, angles; all determine the efficacy and abundance of blood flow in the human retina that hold indispensible relevance for optimal vision and might be subtle indicators of micro vascular damage in disease states. This study has elucidated retinal vascular geometrics of healthy and diseased Indians, a knowledge that can improve our understanding of ‘abnormal features’ and ‘natural variants’ in retinal vascular architecture. In this study, we quantified the ‘structural factors’ behind perfusion defects of the Diabetic retina.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Topological Optimisation'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles