Topology Design Research Articles

Topologic-thermal synergism analysis for wedge-shaped channels leveraging data mining and self-organization geometries

Heat transfer enhancement is particularly difficult to achieve within narrow space and turning channels due to strong structural constraints plus flow recirculations. Traditional designs usually follow periodic topology layout of simple geometric features, such as pin-fin arrays, to distribute cooling for narrow turning channels, lacking alignment with specific design objectives and the constraints. This is attributed to three main issues: the absence of control methods for complex structures, the lack of data for variable topologies, and insufficient understandings of Topologic-thermal Synergism. To address these challenges, the integration of self-organization geometry and the constrained Bayesian optimization method is employed. The channel is divided into 15 regions: the left region is subjected to solid presence control and anisotropy determination, while other regions are assigned control parameters, enabling self-organizing parameterization in design region. The parameters then are optimized using a constrained Bayesian optimization approach, aimed at maximizing the thermal performance factor (TPF) while constraining the area of low heat transfer regions. The optimization process begins with 216 samples to build the initial surrogate model, followed by 30 optimization iterations, resulting in the creation of high-performance complex structures and the establishment of a topology database. Furthermore, the SHAP method is utilized to extract topology design guidelines based on the most influential parameters and their beneficial variation directions. The guideline serves to guide the topology layout of other cooling structures in similar design scenarios. Results demonstrate that optimized self-organized structure enhanced the overall thermal parameter by 70% and decreased the low heat transfer zones by 74% when compared with pin fin structures. Data mining identified material orientation and generation on the left-side region as critical factors in topological structures, significantly influencing overall heat transfer performance. Leveraging the obtained design guidelines, a topological layout for a guiding pin fin structure is redesigned in wedge-shaped channels with varying contraction ratios, achieving performance improvements without the need for additional computational resources. The outcomes of this work hold scientific significance and industrial application value in enabling rapid design of high performance heat transfer structures.

Programmable Shape-Morphing Enables Ceramic Meta-Aerogel Highly Stretchable for Thermal Protection.

Ceramic aerogels hold significant potential for thermal insulation, yet their mechanical stretchability and thermal stability fall short in extreme environments. Here, the study presents a programmable shape-morphing strategy aimed at engineering a binary network topology structure within ceramic aerogels to effectively dissipate stress and block heat transfer. The special topology design, which includes kirigami lamellated aerogels for bearing loading stress and randomly assembled aerogels for mechanical energy pre-storage to transfer tensile stress, effectively achieves unexpected mechanical tensile properties and thermal stability. The resulting robust meta-aerogels demonstrate remarkable structural stability with topology-derived mechanical tensile of up to 85% strain, excellent resilience to 500 cycles of 50% tensile strain, 1000 cycles of 60% buckling strain, and 500 cycles of 50% compressive strain, temperature-invariant tensile recovery capability; simultaneously, low thermal conductivity of 33.01mW m-1 K-1 and tensile-invariant thermal insulation makes the ceramic meta-aerogels an ideal substitute material for various applications.

Topology optimization of multi-material structures subjected to dynamic loads

Traditional designs for multi-material structures are mostly based on static loads. However, engineering structures are often subjected to dynamic loads. This paper firstly and systematically conducts an in-depth study on the topological design of multi-material structures under dynamic loads. In this method, the definition of design variable adopts the ordered solid isotropic material with penalization (ordered-SIMP) method to normalize the design variable, without introducing any additional variables, the HHT-α method is employed to solve the dynamic optimization problem. To address the dynamic optimization problems with constraints on mass and cost, a convex optimization method based on the concept of sensitivity separation is used to update the design variables, and search for the structural topologies. Finally, this paper provides some numerical examples with respect to time-varying, material parameters, load amplitude, load direction and multiple loads, to discuss in depth the topological and numerical results of these examples.

Analysis of Laser Intersatellite Links and Topology Design for Mega-Constellation Networks

Analysis of Laser Intersatellite Links and Topology Design for Mega-Constellation Networks

Two-dimensional magnetic field diagnostics of plasma based on nano-thin-film probe

In this paper, we propose a method to determine the diagnostics of magnetic fields based on arrays of nano-thin-film probes that are manufactured by using magnetron sputtering-based fabrication and arranged in a two-dimensional (2D) topological design. Measurements of the magnetic field and its wave number based on the proposed method were validated in a linear cylindrical plasma device, the linear experimental advanced device. We manufactured nano-thin-film probes, each with a thickness of 500 nm, a diameter of 9 mm, and a shape similar to the Greek letter “omega” by depositing silver nanoparticles generated through magnetron sputtering to improve the accuracy of the fabrication as well as their time response. The 2D topological arrangement of the array of probes enabled the determination of the diagnostics of the magnetic field and its wave number at a high spatial resolution. Measurements of the amplitude of the magnetic field and its wavenumber obtained using the proposed method were in good agreement with the results of theoretical simulations in COMSOL, which verifies its high reliability and accuracy in obtaining low-pressure plasma diagnostics. In future work, we plan to apply our diagnostic method based on the array of thin-film probes to scenarios that require a high spatial resolution.

Multidisciplinary Optimization of Gyroid Topologies for a Cold Plate Heat Exchanger Design

Abstract The strive to reduce the environmental impact of aviation has led to electrification and increasing demand for powerful on-board power electronic systems. These high-performance electrical components are bound to produce significant amounts of low-quality heat waste that, if not dissipated properly, will lead to malfunctioning and even permanent damage. For this reason, high-performance heat exchangers (HX) represent a key enabler for future advances in aircraft systems electrification and are vital to meet net zero goals and reduce the aviation's carbon footprint. For a given volume of the exchanger, the heat flow rate can be increased by adopting more sophisticated fluid domains. However, excessive geometrical complexity will lead to an increase in pressure losses, often resulting in inhomogeneous temperature distributions. In this paper, a novel optimization procedure is employed to maximize the efficiency of a high-performance heat exchanger, while minimizing overall pressure loss and temperature gradients. The optimization is performed with full three-dimensional high-fidelity computational flow simulations. The geometry of the fluid domain is constituted by triply periodic minimal surfaces (TPMS), with a parametrization based on thickness and aspect ratios, done by using the ntopology suite. To assess the performance gain, the topology-optimized design is compared against the datum case and a conventional serpentine design.

Topological Design and Mechanical Manipulation of Matrix-Free Polymer Grafted Nanoparticles Driven by Bond Exchanging

Topological Design and Mechanical Manipulation of Matrix-Free Polymer Grafted Nanoparticles Driven by Bond Exchanging

Topology optimization for metamaterials with negative thermal expansion coefficients using energy-based homogenization

Since the existing topology designs of negative thermal expansion metamaterials are primarily based on the asymptotic homogenization theory, this paper conducts a topology optimization method of negative thermal expansion metamaterials based on the computationally efficient energy-based homogenization for the first time. In this research, (1) a new effective thermal stress coefficient equation is pioneeringly proposed using energy-based homogenization frame, where its theoretical derivation process is presented as well as its effectiveness and computational efficiency are verified by comparative cases. Additionally, the matlab code is open-sourced for public learning. (2) A topology optimization design of both 2D and 3D metamaterials with negative thermal expansion properties is established innovatively with Discrete Material Optimization (DMO). Its advantages are illustrated compared with the convectional method and its results are validated by Finite Element Method simulations. The new methods have promising applications in the evaluation and optimization of thermal expansion properties of composites.

Current status and challenges of lightweight design and manufacturing technology for aerospace structures

Lightweight technology refers to the technology of reducing the structural mass by optimizing materials, structures and manufacturing processes while meeting the requirements of structural performance. It has become one of the key technologies for the development of the new generation of aerospace equipment. This paper first analyzes the development history of lightweight technology. Secondly, from the perspectives of design principles, composition methods and optimization methods, three types of lightweight design methods are introduced: bionic structure design, cellular structure design and efficient topology optimization design. Then, from the perspective of lightweight manufacturing processes and modes, the application of additive manufacturing, collaborative manufacturing and composite material manufacturing in lightweight manufacturing of aerospace structures is explained. Finally, the challenges and future development of lightweight technology are discussed.

Multi-objective topological design considering functionally graded materials and coated fiber reinforcement

This study presents a multi-objective topology optimization method tailored to structures fabricated from functionally graded materials (FGMs), coated FGMs, and coated fiber-reinforced composite materials (FRCMs) with fixed fiber thickness. The design objective is the simultaneous minimization of elastic and thermal compliance. The material properties of these composite materials were derived to generate datasets using the representative volume element method under periodic boundary conditions. Subsequently, machine learning modules were developed based on the datasets to combine with the design process. The multi-objective optimization problem was addressed using the weighted sum method ensuring the generation of the Pareto front. The adaptive weighting strategy is employed to avoid biased results toward a single objective function. To define the coated boundaries within the design domain, image post-processing techniques such as convolution filters, interpolation schemes, and erosion methods were employed on the material layout information of the optimized FGM structures. Through numerical examples, optimized material layouts for coated assemblies incorporating FGMs and FRCMs are presented, with the performance verified through objective function values.

Enhancing interconnection network topology for chiplet-based systems: An automated design framework

Chiplet-based systems integrate discrete chips on an interposer and use the interconnection network to enable communication between different components. The topology of the interconnection network poses a significant challenge to overall performance, as it can greatly affect both latency and throughput. However, the design of the interconnection network topology is not currently automated. They rely heavily on expert knowledge and fail to deliver optimal performance. To this end, we propose an automated design framework for chiplet interconnection network topology, called CINT-AD. To implement CINT-AD, we first investigate topology-related properties from the perspective of design constraints and structural symmetry. Then, using these properties, we develop an automated framework to generate the topology for interposer interconnections between different chiplets. A deadlock-free routing scheme is proposed for the topologies generated by CINT-AD to fully utilize the resources of the interconnection network. Experimental results show that CINT-AD achieves lower average latency and higher throughput compared to existing state-of-the-art topologies. Furthermore, power and area analysis show that the overhead of CINT-AD is negligible.

Steering linkage topology design using angle-based block partitioning symmetric model (APSM)

Steering linkage topology design using angle-based block partitioning symmetric model (APSM)

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 %.

Research on multi-objective topology optimization of unmanned sightseeing vehicle frame based on Analytic Hierarchy Process

To optimize the frame of a sightseeing vehicle, this paper proposes a multi-objective topology optimization method combining Analytic Hierarchy Process (AHP) and topology optimization. Firstly, the edges of the unmanned sightseeing car are statically analyzed. The rectangular steel frame structure of the original frame is replaced with square plates, the basic model of the unmanned sightseeing car frame is established, and a single-objective topology optimization mathematical model of the frame is established to optimize the topology design of the frame. Then, in order to design a frame structure that meets all the working conditions at the same time, a mathematical model of multi-working condition topology optimization is established, and the weights of each working condition are determined by using AHP, and the multi-working condition topology optimization design of the frame is carried out. Finally, a comparison of the comprehensive performance of the frame before and after optimization shows that the proposed method enables the optimized frame to meet the strength requirements under various working conditions, resulting in a weight reduction of 16.5 kg.

Phononic crystal-based acoustic demultiplexer design via bandgap-passband topology optimization

The wave demultiplexer, which selectively transports specific frequencies from incident waves, has garnered considerable interest for its applications across various engineering disciplines. This study introduces a new customizable design method for acoustic demultiplexers based on the topology optimization of phononic crystals (PnCs). To achieve an acoustic demultiplexer capable of filtering multiple frequencies, a topological design model for PnCs that simultaneously considers bandgaps and passbands is proposed. By assembling the optimized PnCs within the structure, the demultiplexer can separate sound waves of different frequencies into distinct output channels. In the optimization model, an objective function based on transmission rates is proposed to determine whether specific frequencies fall within the specified bandgap or passband. To solve this complex topology optimization problem, the Kriging-based material-field series expansion (KG-MFSE) approach is used to describe the material distribution and optimization of PnCs. The designed PnC unit cells can be directly integrated into the demultiplexer without requiring additional space. Based on specified combinations of passbands and bandgaps, different PnCs are designed to realize a programmable acoustic demultiplexer capable of filtering various sound waves. Numerical analyses demonstrate that the constructed acoustic demultiplexer effectively separates the specified frequencies. Finally, experimental validation of the 3D printed acoustic demultiplexer model confirms the effectiveness of the proposed optimization method.

Topology design of variable speed drive systems for enhancing power quality in industrial grids

In the last two decades, a rapid increase in the utilization of non-linear loads within electrical grids has been observed. Consequently, elevated levels of harmonics are found in both voltage and current waves, and adverse effects on power quality are caused. In this context, the variable speed drive (VSD) systems are considered a significant non-linear contributor. To mitigate the harmonic content in VSD systems, various techniques are explored, such as electronic smoothing inductor incorporation in the DC-link, active filters utilization at the grid side, and passive filters integration. A technique centered on the reconfiguration of the DC-link in the VSD systems is proposed in this paper to improve the overall performance of the VSD systems. The configuration comprises two transistors and two diodes, along with smoothing inductors and a capacitor to enhance power quality in the VSD systems. The utilization of three-stage sine pulse width modulation (SPWM) control technology ensures accurate control of the switches, generating optimal control signals that enhance the power quality of the voltage and current waves at the grid side. The effectiveness of the proposed approach is tested via time-domain simulation in MATLAB/Simulink under both constant and variable loading conditions and is verified using a laboratory prototype. The obtained results demonstrate a notable improvement in power quality, showcasing reduced total harmonic distortion (THD) in AC voltage and current waveforms, as well as minimized ripple factor in the DC-link when compared to existing methods.

Stress-constrained concurrent multiscale topological design of porous composites based on discrete material optimisation

Porous composites have attracted increasing attention in recent decades. This study develops a concurrent multiscale topology optimisation (CMTO) method under a prescribed stress constraint for designing porous composites with multi-domain microstructures. First, to address the difficulty of predicting local stress due to varying of microstructural type throughout the optimisation process, a continuous and differentiable stress measure is proposed to effectively approximate the local stress. Second, an inverse homogenisation method based on isogeometric analysis (IGA) is developed to improve the accuracy of stress prediction, and then it is integrated into a CMTO which is developed based on the discrete material optimisation (DMO) interpolation scheme. Third, a stress constraint which is differentiable with respect to both macro and micro design variables is proposed to enable the stress-constrained concurrent optimisation of the macrostructural configuration, microstructural configuration and distribution. Fourth, a novel post-processing approach is established to achieve smooth while volume preserving contour of unit cells with layouts. Finally, two benchmark design examples, namely l-bracket and Crack problems, are implemented using the presented CMTO under a global stress constraint to demonstrate the effectiveness of the proposed method. The result indicates that the proposed method can effectively decrease the stress concentration via three design manners, i.e., the macrostructural configuration, microstructural configuration and distribution. Also, an “interface-enlarging” phenomenon was interestingly but reasonably found in those cases when subjected to stress-constraint considerations.

Development and Optimization of Micro‐Nanotopographical Platforms for Surface Enhanced Raman Scattering Biomolecular Detection

AbstractTopologically designed micro‐ and nanostructured surface‐enhanced Raman scattering (SERS) substrates propel the advancements of innovative applications, including environmental and forensic point‐of‐care miniaturised devices via enhancing the localised electric fields for accurate analyte sensing. Herein, a method for designing, optimising and fabricating fine‐tuneable concentric hexagonal, triangular and rectangular SERS‐active micronano‐substrates is developed, with each unit yielding significant enhancement. Numerical simulations of the 3D near‐field electric field guided the optimal design process. While the coaxial SERS substrates consistently outperformed their solid counterparts, the hexagonal micro‐nano topologies exhibited ×21 higher signal than coaxial square arrays and a 12‐15‐fold increase over the triangle structures. Alternation of the topological designs from square to triangle lattice yielded more uniform plasmonic modes propagating along the 60°‐directions with various resonance modes playing key roles in light reflectance. This enables the engineering of platforms with tailor‐enhanced signals by changing the arrangement of micro‐nano patterned coaxial arrays. The fabricated SERS substrates are validated by detecting traumatic brain injury biomarkers, effectively yielding the characteristic fingerprint spectra of each neuro‐molecule. The straightforward development of sub‐micrometre tuneable SERS‐active architectures enables anelegant route for high‐throughput biochemical sensing, laying a platform for amplified bimolecular detection of disease biomarkers and integration in bioanalytical systems.

Tailored Functionally Graded Materials design and concurrent topology optimization with implicit fields

Tailored Functionally Graded Materials (FGMs) offer the ability to design and engineer materials with specific properties at a changing volume fraction and are widely used in various fields such as aerospace, biomedical engineering, etc. The precise control of physical properties and the connectivity of microstructural sequences are two main challenges in multiscale problems. This paper constructs a novel optimization model for generating FGMs under customized performance, employing an implicit field representation governed by tensor product B-splines. The cross-sectional profile aligns with a microstructure, and thus varying heights correspond to a sequence of microstructures. Fine-tuning the implicit field on connectable FGMs is achieved by optimizing specific properties and addressing the 2-norm problem under connectivity constraints. Therefore, these FGMs can serve as fundamental units for bottom-up multiscale infills. Additionally, we also develop a new model to investigate a more universally applicable concurrent topology optimization method without initial input restrictions. These multiscale optimization results demonstrate excellent performance under tested working conditions.

Imine‐linked covalent organic frameworks: Recent advances in design, synthesis, and application

AbstractCovalent organic frameworks (COFs) are new porous organic materials made of organic building blocks precisely constructed by strong covalent bonds. These new materials feature tunable structure, permanent porosity, high crystallinity, high specific surface area, and excellent stability, which enable COFs to be used in many applications. Linkage chemistry is a key factor in the synthesis of COFs and the control of their physicochemical properties. The boroxine, boronate‐ester, imine, hydrazone, imide, and C=C linkages have been widely used in the construction of COFs. Among the various linkages, imine has become the most important linkage for the COFs due to the easy formation of imine linkage with structural and functional diversity. Over the past decade, imine‐linked COFs have made significant progress and become an indispensable part of various applications of COFs. Here, we aim to provide a comprehensive review of the research progress in the field of imine‐linked COFs, especially the advances in topology design and COF powder and film preparation, and their important advances in gas adsorption, catalysis, and optoelectronic devices. Finally, we discuss the challenges in the design, synthesis, and application of imine‐linked COFs, and present our views on the further development of imine‐linked COFs.