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•A new design optimization methodology for a multifunctional metamaterial is proposed.•A 3D metamaterial with tunable thermal expansion and wide bandgaps is designed.•The effects of ...geometric parameters on metamaterial properties are discussed.
Metamaterials have been extensively investigated owing to their unusual properties. However, the design of multifunctional metamaterials requires further investigation. This study focused on the design of three-dimensional (3D) metamaterials to achieve tunable negative thermal expansion and phononic bandgap properties. First, the independent continuous mapping (ICM) topology optimisation method was applied to create metamaterial microstructures with negative thermal expansion properties based on the multi-scale asymptotic homogenisation theory. Secondly, the conceptual structure from the topology optimisation was reconstructed and parameterized to achieve the desired phononic bandgap widths under negative thermal expansion, using a surrogate model-based optimisation method. Both the negative coefficient of thermal expansion and phononic bandgaps were verified through numerical simulations. The results reveal that, by selecting appropriate parameters, the designed metamaterials can have both a negative coefficient of thermal expansion and a maximum bandgap width ratio. The proposed method provides an important reference for the rational design of multifunctional metamaterials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Several important design criteria have been suggested on designing optimal structures with minimum weight and without fatigue failure.•Several case studies have been provided to illustrate the ...effects of different fatigue criteria on optimal structures with minimum weight.•The effectiveness of the those criteria is partially proved through comparison with conventional stiffness optimization on various examples.•The results and suggestions are based on reliable bi-directional structural optimization method and has great potential to be used in various structures involving a possible fatigue failure.
As one of the failure criteria with ascending importance for engineering problems, fatigue has recently been considered in topology optimization and different optimal topologies have been obtained which satisfying one or two fatigue failure criteria considered in the codes. The topologies and performance of those optimal designs are different if a different fatigue criterion is considered. Those difference may bring some concerns when those topologies are used in the real practice. In this paper, three different fatigue criteria are considered as constraints in structural optimization based on bi-directional evolutionary structural optimization. A modified p-norm approach is employed to decrease the computational cost for all examples. Comparisons of topologies and performance of the resultant optimal designs together with that from traditional compliance minimization designs clarify the effect of different fatigue criteria on those optimal designs for different design problems. These results will provide useful reference for engineers to design structures to avoid high frequency fatigue failure.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Breakthroughs in the field of object recognition facilitate ubiquitous applications in the modern world, ranging from security and surveillance equipment to accessibility devices for the visually ...impaired. Recently-emerged optical computing provides a fundamentally new computing modality to accelerate its solution with photons; however, it still necessitates digital processing for in situ application, inextricably tied to Moore's law. Here, from an entirely optical perspective, we introduce the concept of neuro-metamaterials that can be applied to realize a dynamic object- recognition system. The neuro-metamaterials are fabricated from inhomogeneous metamaterials or transmission metasurfaces, and optimized using, such as topology optimization and deep learning. We demonstrate the concept in experiments where living rabbits play freely in front of the neuro-metamaterials, which enable to perceive in light speed the rabbits' representative postures. Furthermore, we show how this capability enables a new physical mechanism for creating dynamic optical mirages, through which a sequence of rabbit movements is converted into a holographic video of a different animal. Our work provides deep insight into how metamaterials could facilitate a myriad of in situ applications, such as illusive cloaking and speed-of-light information display, processing, and encryption, possibly ushering in an "Optical Internet of Things" era.
•New fin pattern for liquid-cooled heat sink is generated by topology optimization.•Performance of fin patterns with different spanwise lengths of design domain are compared.•Three rows of sectional ...fins reduced the overall pressure drop in present TO design.•Topology design required 54 % lower pumping power compared to straight channels.•Topology design delivered 3 to 4 °C lower junction temperature compared to existing designs.
Topology optimization generate promising ‘heat sink fin layouts’ to satisfy the thermo-hydraulic objectives with lightweight designs. This article evaluates the performance of topology-optimized liquid-cooled heat sinks with different spanwise length-based design domains. A reduced-scale model (with 1/8th the width of the full-scale heat sink model) is selected and optimized with ‘pressure drop’ and ‘average junction temperature’ as objective functions and constraints, respectively. Fin layouts consisting of non-continuous fins are derived for different inlet flow velocities and temperature constraints using an accurate two-dimensional (2D) mathematical model, mimicking a three-dimensional (3D) heat sink geometry. Three-dimensional CFD simulation is used to compare the performance of the present fin layout with a reference topology-optimized design (with 1/16th the width of the full-scale model) and an augmented straight channel-based heat sink. To cool the heat sink to an average junction temperature of 50 °C, the present design requires 17 % and 54 % lower pumping power compared to the reference design and straight channel with significantly reduced material volume. Flow phenomena such as secondary flow-induced mixing and frequent reinitialization of boundary layers at leading edges of fins are observed during numerical investigation which are illustrated using velocity and temperature contours. The optimized fin layout's overall performance is compared with existing fin designs of heat sinks such as step fins, offset strip fins, oblique fins, and oblique and trapezoidal fins. Oblique and trapezoidal fin and oblique fin compete with topology optimized design which outperforms at lower flow rates (for velocity ranging from 0.05 m/s to 0.175 m/s). The average junction temperature using Oblique and trapezoidal fins and oblique fins are 63 °C and 61.22 °C, respectively compared to 58.5 °C for topology-optimized design with a similar pressure drop of 300 Pa.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The study discussed in this paper focuses on additive manufacturing (AM) of intricate geometrically structured components of a prosthetic leg. The objective is to optimize the original design to ...reduce the need for support structures while maximizing stiffness and reducing weight. Making a prosthetic leg lighter can improve the mobility of a person and reduce the energy required to climb stairs, enhancing their quality of life and independence. Traditional manufacturing methods, such as injection molding and computerized numerical control (CNC) machining, have limitations in terms of design flexibility. The study used Selective Laser Melting (SLM) technology with 316L-A stainless steel powder. The optimization process focused on the knee, upper leg, lower leg, hydraulic, and oil support system. The workflow procedure for additive manufacturing was discussed. Overall, the study successfully reduced the weight of the prosthetic leg by 50% from the original model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper proposes a multidisciplinary topology optimization design model and method for the cold plate of active phased antenna array. Aiming at the characteristics of multidisciplinary integration ...of active phased antenna array, a multidisciplinary analysis model considering the thermal effect is established. Based on the multidisciplinary analysis model of antenna array, topology optimization method is used to establish a multidisciplinary optimal design model for the cold plate of antenna array. Since there is no explicit relationship between the electrical performance indicators of the antenna and the topological design variables, the adjoint method is used to derive the adjoint-governing equations that simultaneously consider fluid flow, system heat dissipation, and antenna electrical performance. The corresponding sensitivity information is obtained by solving the adjoint-governing equation. The correctness and effectiveness of the proposed model and method are verified by typical cases.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Periodic cellular structures are widely used in structural protection due to their lightweight and excellent energy absorption characteristics, but the corresponding crashworthy design is still ...limited. Based on the framework of hybrid cellular automata (HCA), the optimal design of periodic cellular structure for crashworthiness is carried out. To guarantee the periodicity of cellular structure, elemental internal energy (EIE) is redistributed averagely as a periodic constraint. Then, by iteratively modifying the local EIE target, the cellular structure is optimized until the maximum energy absorption (EA) is obtained under the specific volume fraction constraint. Through several 2D and 3D numerical examples, this design method is proved to be efficient for the crashworthiness design of periodic cellular structures. Specifically, EA of the optimized cellular structures in this study can be improved by design comparing with solid structures and classical honeycombs. Effects of cellular number and volume gradient on crashworthiness are also discussed.
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•An intelligent approach for designing acoustic TIs is proposed.•Topology optimization finds double Dirac cones at the desirable frequency.•Topological trivial and non-trivial ...phononic crystals are optimized.•Robust propagation and spin-locked unidirectional transmission are presented.•The acoustic topological insulators show high transmission over a wide band.
For the realization of topologically protected wave propagation, engineering artificial structures of topological insulators (TIs) inspired by quantum mechanics has attracted extensive attention over the last few years. However, the existing structures commonly compose of a regular shape of inclusions for the limited arrangements in the unit cell. This paper develops a topology optimization approach for designing novel structures of acoustic TIs. With the mechanism of acoustic TIs based on the quantum spin Hall effect (QSHE), topology optimization first seeks sonic crystals (SCs) with double Dirac cones of dipolar and quadrupolar modes. Then, topology optimization creates topological trivial and non-trivial SCs by breaking the double Dirac cones, which freely assemble into acoustic TIs. The optimized structures exhibit the typical functionalities of acoustic TIs, the robust propagation and spin-locked unidirectional transmission of topological edge states, verifying the effectiveness of the proposed approach.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Lightweight cellular structure generation and topology optimization are common design methodologies in additive manufacturing. In this work, we present a novel optimization strategy for designing ...functionally graded cellular structures with desired mechanical properties. This approach is mainly by generating variable-density gyroid structure and then performing graded structure optimization. Firstly, the geometric properties of the original gyroid structures are analyzed, and the continuity and connectivity of the structures are optimized by adding a penalty function. Then, a homogenization method is used to obtain mechanical properties of gyroid-based cellular structures through a scaling law as a function of their relative densities. Secondly, the scaling law is added directly into the structure optimization algorithm to compute the optimal density distribution in part being optimized. Thirdly, the density mapping and interpolation approach are used to map the output of structure optimization into the parametric gyroid structure which results in an optimum lightweight lattice structure with uniformly varying densities across the design space. Lastly, the effectiveness and robustness of the optimized results are analyzed through finite element analysis and experiments.
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•The geometric continuity and connectivity of gyroid is optimized.•Scaling law of gyroid is obtained by using homogenization method.•Generating gyroid-based FGCS by structure optimization method.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Isogeometric topology optimization (ITO) uses the same mathematical representation to integrate design, analysis and optimization, with high efficiency and accuracy. However, due to the complex ...optimized structures, the automatic generation of an editable model is still challenging. To solve this problem, we present an automatic construction method to generate editable CAD models in terms of the control points of ITO. This method takes the design variables as high-dimensional coordinates of the control points, and based on the coordinates, the boundary information of an optimized 3D geometric model can be automatically obtained by a series of geometric algorithms such as surface/plane intersection algorithm, surface skinning algorithm, and plane trimming algorithm. Therefore, the ITO result model is a boundary representation (B-Rep) consisting of skinned non-uniform rational B-spline (NURBS) surfaces and trimmed planes. Four examples are tested to demonstrate that the proposed method can automatically obtain selectable and editable CAD models, which break through the bottleneck of integrating design, analysis, and optimization.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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