Topology Design Method Research Articles

High-Efficiency and Ultrawideband Polarization Conversion Metasurface Based on Topology and Shape Optimizaiton Design Method

This study introduces a two-stage optimization method for designing an ultrawideband polarization conversion metasurface. By integrating topology and shape optimization techniques, the proposed method expands the design space to achieve enhanced polarization conversion bandwidth. The first stage employs genetic-algorithm-based topology optimization to establish the initial structural configuration through binary coding. Subsequently, the second stage refines the design through shape optimization by extracting and modifying the boundaries of the topology-optimized structure. The optimized design demonstrates high polarization conversion efficiency (>90%) across 4.08–14.39 GHz, yielding a relative bandwidth of 111.64%, which represents a 4.88% improvement compared to topology-only optimization. This enhancement demonstrates the effectiveness of our combined optimization method in ultrawideband polarization conversion metasurface design, offering a promising method for developing high-performance electromagnetic devices.

Topology optimization of rectangular parallel plate heat exchanger unit

This research develops computational optimization applied, for the first time, to Rectangular Parallel Plate Heat Exchanger unit (RPP-HEX-U). This is by employing Finite Element Analysis coupled to topology design method. New innovative fins design are obtained that enhance importantly the overall thermal performance and efficiency of the RPP-HEX-U. The new design indicates that the new topology-optimized fins outperform traditional ones (cylindrical, rectangular, and chevron-type plate fins) in enhancing heat exchange performance and preventing local dead zones formation. The obtained Nusselt number (Nu) of the topology-optimized fins design is significantly higher, with an increase of 5.77% to 8.23% compared to traditional cylindrical and rectangular fins, respectively. The Performance Evaluation Criterion (PEC) values of the topology-optimized fins range from 1.71 to 2.12, thus indicating superior overall performance. Three-dimensional numerical simulations confirmed the effectiveness of these fins in disrupting boundary layer development and enhancing heat transfer within the RPP-HEX-U. The innovative fin design, feasible for manufacturing via stamping technology, adds additional value thanks to the industrial feasibility of the present approach.

Data-driven multi-fidelity topology design of fin structures for latent heat thermal energy storage

This work develops a data-driven multi-fidelity topology design (MFTD) method for designing fins in a latent heat thermal energy storage tube. The high-fidelity simulation resolves the actual solid-liquid phase change process using the enthalpy method, while the low-fidelity topology optimization (TO) simply considers the natural convection with Darcy flow. The above MFTD method is integrated into the framework of evolutional algorithm, and the variational autoencoder is introduced to generate new offspring. Fins for accelerating the melting and solidification processes at different Grashof number (Gr) are designed. It is found that when the fin volume fraction is low, the melt designs exhibit strong heterogeneity due to the strong convection, while the solidification designs are almost isotropic. Along with the increase of the fin volume fraction, the fins are first getting longer, then having more branches or sub-branches and finally becoming thicker. The superiority of the present data-driven MFTD method to the gradient-based direct TO method for solving optimization problems with strong multimodality has been demonstrated in this work. Results find that compared with the designs from direct TO, the MFTD melt design can further reduce the melting time by at least 27 % and 20 % at Gr = 3.3 × 103 and Gr = 3.3 × 104 respectively, and the MFTD solidification design can further shorten the solidification time by at least 9 %.

Irregular IRS-aided SWIPT secure communication system with imperfect CSI

The performance of traditional regular Intelligent Reflecting Surface (IRS) improves as the number of IRS elements increases, but more reflecting elements lead to higher IRS power consumption and greater overhead of channel estimation. The Irregular Intelligent Reflecting Surface (IIRS) can enhance the performance of the IRS as well as boost the system performance when the number of reflecting elements is limited. However, due to the lack of radio frequency chain in IRS, it is challenging for the Base Station (BS) to gather perfect Channel State Information (CSI), especially in the presence of Eavesdroppers (Eves). Therefore, in this paper we investigate the minimum transmit power problem of IIRS-aided Simultaneous Wireless Information and Power Transfer (SWIPT) secure communication system with imperfect CSI of BS-IIRS-Eves links, which is subject to the rate outage probability constraints of the Eves, the minimum rate constraints of the Information Receivers (IRs), the energy harvesting constraints of the Energy Receivers (ERs), and the topology matrix constraints. Afterward, the formulated non-convex problem can be efficiently tackled by employing joint optimization algorithm combined with successive refinement method and adaptive topology design method. Simulation results demonstrate the effectiveness of the proposed scheme and the superiority of IIRS.

Comprehensive study on fail-safe topological design method for 3D structures

Comprehensive study on fail-safe topological design method for 3D structures

Target-oriented inverse optimization design of phononic crystals with variable constraints for vibration attenuation

Previous research on phononic crystals (PnCs) design mostly focused on the maximum band gap (BG) between adjacent orders and could not optimize the desired target frequency based on actual engineering problems. In order to achieve an arbitrarily specified BG structure of PnCs near the target frequency, a new topology design method for PnCs is proposed using a special triangular lattice PnC as the object. In the genetic algorithm (GA) optimization framework, two variable constraint optimization strategies, fixed-step and adaptive, are proposed to form a variable constraint genetic algorithm (VC-GA), which enables the non gradient optimization process to be continuous and uninterrupted. This optimization model also divides optimization into two stages, which can search for target individuals and maximize BG under the constraints of the target BG. Combining the optimization model with the improved fast plane wave expansion method (IFPWEM) for optimizing the single and multi-objective BGs in the in-plane and out-of-plane modes, and the weight coefficient is introduced to broaden its scope of application. The effectiveness of the method is verified through experiments, and the vibration reduction optimization design is carried out within a specific frequency range for the engineering structure corrugated plate as an example.

Latent Crossover for Data-Driven Multifidelity Topology Design

Abstract Topology optimization is one of the most flexible structural optimization methodologies. However, in exchange for its high level of design freedom, typical topology optimization cannot avoid multimodality, where multiple local optima exist. This study focuses on developing a gradient-free topology optimization framework to avoid being trapped in undesirable local optima. Its core is a data-driven multifidelity topology design (MFTD) method, in which the design candidates generated by solving low-fidelity topology optimization problems are updated through a deep generative model and high-fidelity evaluation. As its key component, the deep generative model compresses the original data into a low-dimensional manifold, i.e., the latent space, and randomly arranges new design candidates over the space. Although the original framework is gradient free, its randomness may lead to convergence variability and premature convergence. Inspired by a popular crossover operation of evolutionary algorithms (EAs), this study merges the data-driven MFTD framework and proposes a new crossover operation called latent crossover. We apply the proposed method to a maximum stress minimization problem in 2D structural mechanics. The results demonstrate that the latent crossover improves convergence stability compared to the original data-driven MFTD method. Furthermore, the optimized designs exhibit performance comparable to or better than that in conventional gradient-based topology optimization using the P-norm measure.

Modularized Inductive Power Transfer Systems With Inherent Impedance Decoupling for High-Power Applications

Due to the capacity and costs of single power electronic devices, the modularized inductive power transfer systems (MIPT) are widely used in high-power electronic applications. To achieve safe and efficient operation of high-power IPT technology, this paper proposes a modularized topology design method with inherent impedance decoupling feature. When the module number changes, the current and voltage stresses of the devices in the proposed system remain unchanged inside modules at the rated power. Moreover, the impedance of any module will not be affected by neighboring modules, especially in cases where the module number may change abruptly. Such a desired feature significantly improves the reliability of high power IPT systems. A 15 kW MIPT prototype with 3 modules connected in parallel is implemented to verify the validity of the proposed method. The result clearly shows that both the impedance and device stress are decoupled with the module number. The system exhibits peak efficiency of 95.1% and over 92.4% when the power is between 2kW and 15kW.

Mechanical metamaterial design with the customized low-frequency bandgap and negative Poisson's ratio via topology optimization

The precise control of both the mechanical deformation and wave propagation characteristics of metamaterial through design holds significant importance and presents a challenging task. This paper proposes a novel two-stage topological optimization design method for customizing both negative Poisson's ratio and locally resonant bandgap in the mechanical metamaterial. In the optimized model, the negative Poisson’s ratio structure is firstly obtained by optimizing the material distribution within the matrix region, then the metamaterial with the customized negative Poisson’s ratio and bandgap range is obtained through the second stage optimization. In the analysis of the metamaterial unit cell, the topology-dependent Poisson’s ratio is calculated based on the equivalent elastic matrix obtained through the homogenization method. The range of bandgap is estimated using the effective mass analytical model of the spring-mass system. Thus, the range of bandgap is determined by only a few geometric parameters instead of topological structure under given assumptions. The customized bandgap ranges can be extended by introducing more resonators into the unit cell and combining different unit cells into an assembled structure. Numerical examples are provided to demonstrate the efficacy of the proposed method.

Electrical Steel Usage and Topology Design Method for HTS Wind Generators

Electrical Steel Usage and Topology Design Method for HTS Wind Generators

Redundant Topology Design Method for Schedule Traffic Transmission Based on IEEE802.1CB Standard: Optimizing NW-PSP Scheduling Performance

This study proposes a method for designing redundant topologies in time-sensitive networking to transmit scheduled traffic (ST) while considering fault tolerance. In general, redundant topologies enhance network fault tolerance and are used in safety-critical applications that demand high reliability. These applications place a premium on real-time network performance, necessitating the consideration of the quality of service for time-critical traffic during the redundant topology design process. The primary objective of this study is to optimize the flowspan, which pertained to the scheduling performance of the no-wait packet scheduling problem during the redundant topology design phase. Specifically, we introduced a methodology for designing topologies tailored to transmit ST using the IEEE802.1CB mechanism. Comparisons with existing topology design approaches revealed the ability of the proposed method to enhance network fault tolerance and yield a topology that reduced flowspan of ST, thereby freeing up bandwidth for time-critical traffic.

Electromagnetic and Mechanical Topology Optimization for SynRM Rotors Considering High Dimensional Constraints

The knowledge-based parametric design process of the rotor topology of the synchronous reluctance motor (SynRM) requires a tedious parameter definition, selection, and searching process until an optimal design can be obtained. This research proposes a topology optimization approach based on solid isotropic material with penalization method for the SynRM rotor topology design. The aim is to pursue a more intelligent and automatic design process. Specifically, the proposed method aims to generate the SynRM rotor design of high output torque profile. Meanwhile, the mechanical constraints including structural compliance and stress etc. are also considered for promising the structural reliability of the rotor. Considering the high dimensional constraints caused by the multi-physics performances, the augmented Lagrangian method based optimization framework is developed to solve the minimization problem in a compact scheme. To prove the effectiveness of the developed method, simulations and analysis on the topology optimization of SynRMs are performed in this research. Prototyping and experiment are also conducted for verifying the performance of the optimized structure.

Optimization Strategies of Covalent Organic Frameworks and Their Derivatives for Electrocatalytic Applications

AbstractCovalent organic frameworks (COFs) are crystalline organic porous polymers that can be precisely integrated by building blocks to achieve pre‐designed composition, components, and functions, making them a powerful platform for the development of molecular devices in the field of electrocatalysis. The precise control of channel/dopant positions and highly ordered network structures of COFs provide an ideal material system for the applications of advanced electrocatalysis. In this paper, the topological structure design and synthesis methods of COFs are reviewed in detail, and their design principles are deeply analyzed. In addition, the applications of COFs and their derivatives in the field of electrocatalysis are systematically summarized and the optimization strategies are proposed. Finally, the application prospects of COFs and their derivatives in electrocatalysis and the challenges that may be encountered in the future are prospected, providing helpful guidance for future research.

End‐to‐end generation of structural topology for complex architectural layouts with graph neural networks

AbstractCurrent automated structural topology design methods can only deal with limited design spaces or simplified architectural layouts for lack of data or a proper representation of structure topology. To address this, the abundant information of manually designed architectural and structural layouts should be exploited to guide the topology design. To achieve automatic generation of structural topologies according to real‐world architectural layouts, this research introduces StrucTopo‐generative adversarial network (GAN), an end‐to‐end generative model with node and edge generation stages based on proper graph representation. Nodes are generated using an image‐to‐image translation model, and edges are generated with a GAN‐based approach. The model is trained and tested on a dataset of 300 complex architectural and structural layouts. Measured against the manually designed topologies, the results indicate that the proposed model can generate reasonable structural topologies, with a recall of 97% and an intersection‐over‐union of 80% in node generation, with a precision of 92% and a recall of 91% in edge generation. Additionally, the joint generation shows a graph similarity of 72%. The proposed model is the first of its kind to consider complex architectural layout constraints in the generation of structural topology, marking a step forward in applying artificial intelligence to practical structural design.

Optimization of material distribution applied to magnet-free rotors of synchronous motors

In a relentless desire to continuously improve the performance of electric actuators, topological optimal design methods present interesting possibilities. In particular, this work applies an optimization approach of material distribution in order to define new configurations of material arrangements (air, steel, copper) for internal parts of machines, that potentially provide better performance. This methodology is applied to different design configurations of magnet-free synchronous machine rotors.

Optimization Effect of the Improved Power System Integrating Composite Motors on the Energy Consumption of Electric Vehicles

The multi-power source coupled transmission system is a high-performance and energy-saving potential power transmission system, and most of the commonly used pure electric vehicles in the market that use multi-power source coupled drive adopt the motor dual-axis distributed independent drive scheme. The configuration design method for multi-power source fusion hybrid systems mainly focuses on the search and selection of power split hybrid systems based on planetary gear mechanisms. But it has not yet covered the configuration design of transmission systems, resulting in a lack of universal expression and generation methods for the configuration of multi-power source fusion hybrid systems in pure electric vehicles. Therefore, to solve the configuration optimization design problem of a dual-motor single-planetary-array power system, an improved general matrix topology design method is proposed to generate all feasible topology structures. And energy consumption, economy, and the dynamic performance of alternative configurations are optimized and simulated through the control strategy based on a dynamic programming algorithm. Under comprehensive testing conditions, 25 alternative options that met the screening criteria were selected, and, ultimately, five optimized configuration options were obtained. Configuration 1 has the best economy, reducing energy consumption by about 6.3%and increasing driving range by about 6.7%. Its 0–100 km/h acceleration time is about 31.4% faster than the reference configuration. In addition, the energy consumption economy during actual driving is almost the same as the theoretical optimal energy consumption economy, with a difference of only 0.3%. The success of this study not only provides an innovative method for optimizing the configuration of dual-motor single-row star train power systems, but also has a positive impact on improving energy utilization efficiency, reducing energy consumption, and improving the overall performance of electric vehicles.

Monitoring information transmission topology of high voltage transmission line

High-voltage transmission lines are long and may cross areas without mobile networks. The transmission tower is equipped with monitoring equipment. The monitoring information of the transmission tower located in the non-mobile network area is difficult to return. What topology is used for transmission is an important engineering problem. When the number of transmission towers passing through the area without a mobile network is large, the traditional information transmission topology design method based on engineer experience cannot be applied. Aiming at the urgent demand of monitoring information transmission of high-voltage transmission lines in strip-shaped non-mobile network areas, an information transmission topology design method based on a unidirectional layered search algorithm is proposed. Firstly, the objective function and constraint function are designed. Then the unidirectional layered search algorithm is used to realize the planning of communication nodes and complete the design of the information transmission topology. The simulation results show that compared with the traditional information transmission topology design method, the design method proposed in this paper is suitable for complex networks, and the transmission delay of the designed information transmission topology is small.

Research on Design Method of Multilayer Metamaterials Based on Stochastic Topology.

Metamaterials are usually designed using biomimetic technology based on natural biological characteristics or topology optimization based on prior knowledge. Although satisfactory results can be achieved to a certain extent, there are still many performance limitations. For overcoming the above limitations, this paper proposes a rapid metamaterials design method based on the generation of random topological patterns. This method realizes the combined big data simulation and structure optimization of structure-electromagnetic properties, which makes up for the shortcomings of traditional design methods. The electromagnetic properties of the proposed metamaterials are verified by experiments. The reflection coefficient of the designed absorbing metamaterial unit is all lower than -15 dB over 12-16 GHz. Compared with the metal floor, the radar cross section (RCS) of the designed metamaterial is reduced by a minimum of 14.5 dB and a maximum of 27.6 dB over the operating band. The performance parameters of metamaterial obtained based on the random topology design method are consistent with the simulation design results, which further verifies the reliability of the algorithm in this paper.

Collective-Coupling Enhanced Ultrabroadband Linear Polarization Conversion on Zigzag-Split Metasurfaces

Polarization manipulation plays a pivotal role in integrated multifunctional devices. Various metasurface-based polarization converters successfully demonstrated high efficiency and broad bandwidth. However, new mechanisms to aggressively enhance performance are still in dire need. Herein, theoretical and experimental evidence corroborates an efficient ultra-wideband transmissive polarization converter based on a topological design method. The triple-layer meta-device consists of a layer of anisotropic zigzag-split resonator array amid two orthogonal wire-grating layers. By splitting double zigzag lines into compound 90°V-shaped resonators, the intra-unit cross-coupling extends to strong inter-unit cross-coupling, giving birth to the multi-resonances enhancement and significant bandwidth broadening. This polarization converter can efficiently convert linearly polarized incident waves into 90° cross-polarized transmitted waves, with a conversion efficiency above 80% over 3.98-22.71 GHz, reaching a fractional bandwidth of 140.4%. The proposed meta-device enables strong cross-coupling in mutual transition from intra-unit to inter-unit. From a physical viewpoint, the novel mechanism is elucidated by the surface current and electric field distributions upon constructive interferences stemming from V-shape-resonator combinations and the Fabry-Pérot-like cavity effect. With both spectrum and function extensions, the proposed polarization conversion strategy finds essential applications in polarization-related systematic scenarios, such as 6G communication, radar imaging, anti-interference, chiral sensing, etc.

3D printing and modelling of continuous carbon fibre reinforced composite grids with enhanced shear modulus

Within this research, continuous carbon fibre (CCF) reinforced polyamide (PA) composite grids were topologically-tailored and 3D printed to show enhanced shear modulus. Based on the 3D printing trajectories, a new numerical scheme to predict the elastic responses and behaviours of the 3D printed CCF/PA composite grids was developed. To verify the design and the numerical model, specifically created shearing tests were performed. By comparison, the modelled data agrees well with the experiments. Reinforced by CCFs, the effective shear modulus of 3D printed PA specimens was found to increase by 641.3%, 437.6% and 723% for basic structural configurations with material volume fractions of 20 vol-%, 40 vol-% and 60 vol-%, respectively. Even more, an index for evaluating the CCF reinforcement efficiency, independent of the design of the reinforced structure, was proposed and applied, indicating that the effective shear modulus can be maximally enhanced by 40.5 MP once the CCF volume content is increased by 1%. This study innovatively provides a systematic approach by integrating topological design, modelling and experimental methods for creating engineering grid structures with enhanced shear modulus, and thus proving the efficiency of using continuous fibres as structural reinforcements in 3D printing for engineering applications.