Structural Design Method Research Articles

A parameterized level set method for structural topology optimization using the approximate re-initialization scheme

This article proposes an efficient parameterized level set method (PLSM) for structural topology optimization design with minimum compliance as the objective function and volume fraction as the constraint condition. In the stage of establishing the optimization model, the level set function (LSF) is interpolated using compactly-supported radial basis functions (CS-RBFs) to transform the Hamilton-Jacobi partial differential equation (PDE) into ordinary differential equations (ODEs), thereby making the evolution of the LSF more convenient and efficient, and ensuring the smoothness of the optimization result boundary. The method of moving asymptotes (MMA) is used for solving the established optimization model, and meanwhile the shape sensitivity constraint factor is added to improve computational efficiency. During the evolution of the LSF, an approximate re-initialization scheme is employed to prevent the gradient of the LSF boundary from being too large or too small, thereby improving the numerical stability and the convergence speed of structural topology optimization process. Furthermore, the proposed method is also extensible and applicable to topology optimization of multi-material structures. The feasibility and effectiveness of this method have been verified through several typical numerical examples involving topology optimization of single-material structures and multi-material structures within the framework of minimum compliance design. HIGHLIGHTS An efficient parameterized level set method using the approximate re-initialization scheme is proposed for structural topology optimization. The approximate re-initialization scheme is employed when solving the parameterized level set function via the MMA algorithm. This scheme can prevents the gradient of the level set function boundary from being too large or too small, making the level set function update more stable and accelerating the convergence speed of structural topology optimization. The effectiveness and feasibility of the proposed method are demonstrated through examples of single-material and multi-material structural topology optimization.

The Development of Structural Design Method of Composite Pavement in Japan

The Development of Structural Design Method of Composite Pavement in Japan

A New Design of Composite Pavement with Asphalt Interlayer between CRCP and Cement Treated Base Course

In Japan, composite pavements are adopted in expressways to ensure a long service life with minimum maintenance work. A typical design of the composite pavement utilizes a porous asphalt surface and a CRCP over a cement treated base course (CTB). An investigation on a 20 years old composite pavement revealed that the CTB was damaged due to water penetration and erosion. This finding promoted us to develop a new type of composite pavement, which introduces an asphalt interlayer (AIL) over the CTB to prevent the erosion. A structural design method for the new design of the new composite pavement was developed based on thermal and load stress calculations and fatigue analysis. Full scale test composite pavements were constructed and thermal and load strains measured on the pavements. A 3DFEM model was developed for stress calculation and validated by comparing the calculated and measured strains. The new design method provides 10 % reduction of fatigue damage by introducing AIL. It was also found that the fatigue damage increases six times if AIL is not used and CTB is eroded.

4D Printed Cardiac Occlusion Device with Efficient Anticoagulation, Proendothelialization, and Precise Localization

AbstractCongenital heart defects (CHDs) are one of the most common congenital malformations, accounting for ≈30% of all congenital malformations. Interventional implantation of occlusion devices is becoming the preferred treatment for CHDs. However, current occlusion devices suffer from serious problems, such as thrombosis, slow endothelialization, imprecise localization, abrasion, displacement, etc. Here, a multifunctional drug‐carrying fiber platform with structural similar to the extracellular matrix is innovatively designed to develop 4D printed cardiac occlusion devices, with characteristics of efficient anticoagulation, proendothelialization, and precise localization. Biomimetic ligament structures are designed to achieve a similar mechanical response to myocardial tissue, which helps to synergize deformation and reduce tissue wear. A structural design method for biomimetic personalized multilevel occlusion devices is proposed, facilitating further improvement of sealing reliability. The radiopaque 4D printed shape memory composites are developed, realizing the complete visualization and precise localization of the device in vivo. The novel 4D printed cardiac occlusion device provides an effective way to reduce the risk of complications and contributes to versatility. It is expected to be a next‐generation multifunctional repair device for personalized treatment of CHDs.

Research on High-Speed Railway Subgrade Design Method Based on Energy Dissipation and Dynamic Stability Characteristics

The subgrade structure of high-speed railways is an important foundation for the safe and smooth operation of high-speed trains, and the scientific design of the subgrade structure provides a fundamental guarantee of its durability and technical economy. As, in the development of high-speed railways in China, higher speeds are being pursued, more requirements have been put forward for the dynamic stability of subgrade structures. To address this issue, this article focuses on the control requirements for the long-term stability of subgrade deformation, and various design methods for high-speed railway subgrade structures are presented. Considering the energy dissipation and dynamic stability characteristics of subgrade filling materials, the dynamic performance of coarse-grained soil filling materials in the bottom layer and graded crushed stones in the surface layer are revealed. The methods for determining the values of dynamic parameters such as the dynamic modulus and damping ratio are provided. Based on the dynamic shakedown theory, the stress–strain hysteresis characteristics of fillers and the variation law of dissipated energy are revealed. The correlation between unit volume dissipated energy and shakedown state under cyclic loading conditions is identified. A criterion for determining the critical shakedown state of high-speed railway subgrade structures based on equivalent unit volume dissipated energy is proposed, and a method for determining the design threshold of dynamic stress and dynamic strain is also proposed. The results show that the shakedown design critical values of equivalent unit volume dissipated energy in the bottom and surface layers of the foundation were between 0.0103~0.0133 kJ/m3 and 0.0121~0.0149 kJ/m3, respectively. The critical dynamic strain range was 0.8 × 10−3~1.3 × 10−3. On this basis, a high-speed railway subgrade design method based on energy dissipation and dynamic shakedown characteristics was developed. The results can provide theoretical support for the design of high-speed railway subgrade structures with different filling material alternatives and control standards.

Research of Grasping Strategy of Bionic Manipulator

This article reviews the research progress of bionic manipulator grabbing strategies in recent years, subsequently, the classification of existing bionic manipulator grabbing strategies was sorted out in detail, including crawling strategies based on the principle of biological inspiration, crawling strategies based on mechanical models and crawling strategies based on intelligent algorithms. First, the paper outlines the structural design and control methods of bionic manipulators. Next, the classification and characteristics of existing crawling strategies are summarized. These include strategies based on biological mechanisms, those guided by intelligent optimization algorithms, and data-driven learning methods. On this basis, the advantages and disadvantages of various crawling strategies and their performance in practical applications are compared and analyzed. Finally, the paper discusses the flexibility of bionic manipulator grabbing strategies, challenges and future development trends in adaptability and intelligence. This review not only provides a comprehensive theoretical reference for researchers in the field of bionic manipulator grasping strategies but also identifies key areas for future technological development.

Elastic robotic structures: a multidisciplinary framework for the design and control of shape-morphing elastic system for architectural and design applications

The design of adaptive structures and objects takes place at the intersection of design, architecture, robotics and engineering. Evolving from 1960s cybernetics to today’s interactive projects, technological advancements shape new visions for adaptive systems. A key challenge in this field is developing human-scale, shape-morphing structures. Elastic materials offer a promising solution for creating lightweight systems capable of large transformations with minimal components and energy, unlike conventional rigid systems. This approach requires methodologies for designing and controlling complex material deformations. While architectural and structural design methods focus on large-scale but static elastic structures, soft robotics explores dynamic behaviors. However these approaches are limited for complex shapes and large-scale, as their focus is on specialized applications. To address these issues, this research introduces a multidisciplinary framework for the design and control of shape-morphing elastic system for architectural and design applications. It also presents the concept of elastic robotic structures (ERS), which refers to a body of work developed with the framework. ERS are defined as large-scale elastic systems that are robotically actuated and can achieve multiple geometrical states, interacting with humans and adapting to diverse conditions. The multidisciplinary framework is presented for ERS design, characterization and control, showing how it leverages the integration of architecture, engineering and robotics to overcome the limitations of discipline-specific traditional approaches. The framework is applied in the realization of different types of ERS, which are presented and categorized. Combining the flexibility and interactivity of design methodologies with the reliability of robotic solutions will enable designers and engineers to develop innovative elastic shape-changing systems and program their behaviors.

4D Printing of Direct-Driven Deformable Wheel with Multiple Programmable Configurations

Abstract Conventional deformable wheel systems in robots and other mechatronic systems face significant challenges in achieving miniaturization, intelligence, and integration. To address these issues, we propose a novel integrated structural design method and 4D printing strategy for deformable wheels capable of shaping among multiple programmable direct-driven deformation configurations. The load-bearing capability of the printed wheel is enhanced by utilizing deformed components in various locations and actuated states. Additionally, a novel analytical design method is presented to determine the structure, actuation, and deformation parameters of each component under complex coupled deformation. Our findings reveal that the designed wheel can transform into three different configurations, exhibiting desired deformations of 14.7% in the radial direction and 14.4% in the axial direction. It also demonstrates robust deformation behavior and structural stability under multi-directional loads. By integrating a terrain sensing system, the designed wheel exhibits highly adaptive deformation capabilities on various terrains, showing great potential for exploring complex environments.

Design Method of Gyroid Lattice Structure Based on the Load Paths Direction and Capacity

The Design of lattice structures with triply periodic minimal surface (TPMS) can improve the specific stiffness, strength, heat dissipation, and energy absorption functions of their physical structures. The load-transferred law in the structure can serve as a crucial basis for the design, including the distribution and anisotropy of the unit cells. In this paper, a design method based on load paths is proposed and a series of Gyroid lattice structures with variable density cells, variable direction cells, and combination of variable density and direction cells, are designed with better mechanical properties. The load paths within a given structure are extracted to explicitly provide the load-transferred law. The capacity of the load paths is then proposed to guide the distribution of the cells, and a mapping relationship with the parameters controlling the porosity is established. The lattice structures with variable density cells are designed. Afterwards, the pointing stress vectors of the load paths is defined as the main load-transferred direction in the local region to guide the direction of the cells. Based on the anisotropic behavior of the Gyroid cells, the direction setting principles are formulated, and the lattice structures with variable direction cells are designed. Furthermore, a model generation method is proposed, and the Gyroid lattice structures that combine variable density and direction cells are implemented. Two models are applied to validate the proposed method, including a two-dimensional three-point bending beam and a three-dimensional supporting beam. The obtained results show that for the same porosity, both the variable density and variable direction designs of Gyroid cells allow to improve the mechanical properties. The variable density design outperforms the variable direction design. In addition, the Gyroid lattice structures combining variable density and direction cells have significantly higher performance, which indicates that the proposed design method can more effectively increase the load-bearing performance.

A Novel CTTC Structure and Optimization Design Method for CLLC Bidirectional Resonant Converter

A Novel CTTC Structure and Optimization Design Method for CLLC Bidirectional Resonant Converter

Mathematically inspired structure design in nanoscale thermal transport.

Mathematically inspired structure design has emerged as a powerful approach for tailoring material properties, especially in nanoscale thermal transport, with promising applications both within this field and beyond. By employing mathematical principles, based on number theory, such as periodicity and quasi-periodic organizations, researchers have developed advanced structures with unique thermal behaviours. Although periodic phononic crystals have been extensively explored, various structural design methods based on alternative mathematical sequences have gained attention in recent years. This review provides an in-depth overview of these mathematical frameworks, focusing on nanoscale thermal transport. We examine key mathematical sequences, their foundational principles, and analyze the influence of thermal behavior, highlighting recent advancements in this field. Looking ahead, further exploration of mathematical sequences offers significant potential for the development of next-generation materials with tailored, multi-functional properties suited to diverse technological applications.

Research Progress on Forming Porous Structures based on Selective Laser Melting Technology

Background: Based on the development of selective laser melting technology, the machining of porous structures has become more delicate than conventional machining methods and has great advantages in manufacturing in many fields. Objective: Types, properties, and design methods of porous structures are described, along with the application areas of porous structures. The influence of SLM process parameters on the molding of porous structures is also described. Methods: Journals on porous structures are cited and used to demonstrate the excellent properties, application areas, and molding processes of porous structures. Results: Porous structures formed based on selective laser melting have excellent properties and are used in a wide range of applications, such as medical phytomers and aerospace. Conclusion: With the combination of selective laser melting technology and porous structure design methods, porous structures are better developed and applied to many fields.

Semiconductive Coordination Polymer with Multi‐Channel Charge Transfer for High‐Performance Direct X‐ray Detection

Coordination polymers (CPs) are promising for direct X‐ray detection and imaging owing to higher designability and outstanding stability, however, it remains a challenge to achieve highly X‐ray detection performance, particularly both high sensitivity and low detection limit at the same operating voltage. Herein, we construct a new conjugated CP {[Co(BPTTz)(DIPA)] DMA}n (1, BPTTz = 2,5‐bis(pyridine‐4‐yl)thiazolo[5,4‐d]thiazole, H2DIPA = 2,5‐diiodoterephthalic acid, DMA = N, N'‐dimethylacetamide), with multi‐channel charge transfer by regulating the linker mediated electronic‐state, which reduces carrier losses resulting from recombination or quenching, enhances the efficiency of charge separation and transfer, thus further optimizes X‐ray detection performance. The semiconductor prepared based on this strategy achieves record values including the highest mobility‐lifetime product (μτ, 8.05 × 10–3 cm2 V–1) and the lowest detectable X‐ray dose rate (128 nGyair S–1, 35 V) among CP‐based direct radiation detectors, as well as a high sensitivity (172 μC Gyair–1cm–2, 35 V) at the same operating voltage. This detector shows excellent long‐time air stability under ambient conditions for over three months and operational stability. These findings demonstrate a rational structural design method to enhance the photoelectronic efficiency and stability of semiconductive CPs.

Semiconductive Coordination Polymer with Multi‐Channel Charge Transfer for High‐Performance Direct X‐ray Detection

Coordination polymers (CPs) are promising for direct X‐ray detection and imaging owing to higher designability and outstanding stability, however, it remains a challenge to achieve highly X‐ray detection performance, particularly both high sensitivity and low detection limit at the same operating voltage. Herein, we construct a new conjugated CP {[Co(BPTTz)(DIPA)] DMA}n (1, BPTTz = 2,5‐bis(pyridine‐4‐yl)thiazolo[5,4‐d]thiazole, H2DIPA = 2,5‐diiodoterephthalic acid, DMA = N, N'‐dimethylacetamide), with multi‐channel charge transfer by regulating the linker mediated electronic‐state, which reduces carrier losses resulting from recombination or quenching, enhances the efficiency of charge separation and transfer, thus further optimizes X‐ray detection performance. The semiconductor prepared based on this strategy achieves record values including the highest mobility‐lifetime product (μτ, 8.05 × 10–3 cm2 V–1) and the lowest detectable X‐ray dose rate (128 nGyair S–1, 35 V) among CP‐based direct radiation detectors, as well as a high sensitivity (172 μC Gyair–1cm–2, 35 V) at the same operating voltage. This detector shows excellent long‐time air stability under ambient conditions for over three months and operational stability. These findings demonstrate a rational structural design method to enhance the photoelectronic efficiency and stability of semiconductive CPs.

High‐Accuracy Recognition Triboelectric Nanogenerator System for Shooting Report and Ballistic Analysis

AbstractThe accuracy and efficiency of shooting reports constitute indispensable cornerstones in modern military training and shooting fields. However, traditional shooting report systems struggle to offer precise and sensitive instant feedback, especially in rare scenarios, such as multiple piercing and shots on the ring boundaries. Simultaneously, ballistic analysis as a pivotal approach in criminal investigations, confronts similar challenges including high costs, complex data processing, and strong professional dependency. Thus, a flexible, high‐temperature resistant, and high‐accuracy recognition intelligent target reporting and ballistic analysis (ITBA) system is designed based on the mechanism of triboelectric nanogenerator (TENG), which recognizes multiple bullet piercings and delivers bullet velocity through a time‐difference algorithm combined with shooting angle to accurately determine the shooting position. Thanks to the novel structural design and preparation method, the ITBA system achieves remarkable integration, lightweight, and industrialization, ensuring exceptional stability even in harsh environments. Furthermore, the ITBA system integrates machine learning techniques to achieve 100% accuracy in bullet material recognition and 97% accuracy in determining shooting angles, providing a solid foundation for enhancing the precision of military training and the scientific rigor of forensic investigations.

Recent Advances and Future Prospects for Construction Strategies of Flexible Electromagnetic Protection Patches

AbstractWith the rapid development of morphing aircraft, increasing demands are put forward for flexible patches (FP). In addition to sufficient deformation capability and mechanical strength, FP are required for electromagnetic continuity especially at active gaps of morphing aircraft. The existing FP are developed with enhanced deformability and load‐bearing capacity, yet their limits in electromagnetic wave (EMW) absorption and electromagnetic interference (EMI) shielding cannot meet practical applications of electromagnetic protection, and their interlayer bonding also needs to be strengthened. Besides, flexible electromagnetic protection materials (FEMPM) have been developed to address electromagnetic radiation in wearable electronics and other fields, yet their deformability and mechanical properties still need to be improved. Thereon, based on reasonable structure design and fabrication methods, delicate integration of FP and FEMPM can offer a significant paradigm to construct flexible electromagnetic protection patches (FEMPP) with great potentials in engineering applications. Herein, recent advances in FP as well as FEMPM are consolidated, and detailed development in multifunctional construction of FEMPP are involved. Furthermore, challenges and developing perspectives are also discussed, aiming to inspire the relevant researches and promote development in the related fields.

Topology Optimization: A Review for Structural Designs Under Statics Problems.

Topology optimization is a powerful structural design method that determines the optimal configuration by distributing materials efficiently within a given design domain while satisfying specified load, performance, and volume constraints. Unlike size and shape optimization, topology optimization is independent of the initial design, offering a broader design space. This paper provides a systematic review of topology optimization methods, covering two theoretical frameworks: linear elasticity and nonlinear theory. Specifically, the review focuses on sensitivity analysis, optimization criteria, and topology solution smoothing within the context of linear elasticity. In the context of nonlinear theory, the review primarily addresses nonlinear phenomena arising from stress constraints, geometric, material, and contact nonlinearities. The paper concludes by summarizing the current state of the field, identifying limitations in existing methods, and suggesting directions for future research.

Numerical simulation of shock initiation characteristics of fusion detonators

Abstract To provide an economic and safe destruction program, this paper is based on the jet detonation method of poly energy charge structure design. The use of simulation software is to establish the diameter of the 40 mm polymer charge physical model, and the combat structure model is used for the invasion and detonation simulation calculations. The results show that the theoretical calculations and simulations are in good agreement and the structure can penetrate the 40 mm thick 50SiMnVB shell, to observe the shock wave in the shielding cover and shielding explosives between the transmission process, finding that the thickness of the shell affects the impact detonation mechanism.

Lattice-like Mechanical Metamaterials Structure Design Method Based on Convolutional Neural Network and NSGA-II Algorithm

Abstract Lattice-like mechanical metamaterials have excellent mechanical properties such as ultra-low density, high specific strength, and high energy absorption, and have broad application prospects in key components of platforms such as armored vehicles, helicopters, and aerospace vehicles. Aiming at the problem of inverse design of superstructure cellular structures, a study on the design method of cellular structures was carried out. Firstly, based on the uniqueness of cellular structural characteristics and the principle of comprehensive information, the cellular structural characteristic matrix and the cellular macroscopic mechanical characteristic matrix of coupled cellular configuration and structural parameters were proposed respectively; then, with the cellular structural characteristic matrix as input data and the macroscopic mechanical characteristic matrix of the cell as output data, a superstructure material performance prediction model based on convolutional neural network was established; further, with the minimum error between the specified target value and the predicted value of the macroscopic mechanical characteristic parameter as the criterion, a multi-objective optimization function was established; finally, the performance prediction model was combined with the fast non-dominated algorithm (NSGA-II algorithm) with elite retention strategy to construct a superstructure cellular structure design model, and the effectiveness of the structural design model was verified by case studies.

A Novel Hand-held Multi-color Magnetic Particle Imaging Device based on Rapid Frequency Conversion.

Multi-color Magnetic Particle Imaging (MPI) technology offers high sensitivity and non-invasive imaging capabilities. It can simultaneously image multiple superparamagnetic iron oxide nanoparticles (SPIOs), facilitating more precise detection of multiple molecular markers in vivo. However, the fixed drive frequency of existing hand-held MPI devices makes it difficult to fully match the nonlinear magnetic response of different SPIOs, affecting the spatial resolution and quantitative accuracy of multi-color imaging. We designed a novel rapid frequency conversion based hand-held multi-color magnetic particle imaging (RFC-MPI) device. This device adjusts the drive frequency based on the nonlinear magnetic response of SPIOs at different frequencies, effectively expanding the system matrix information and thereby improving spatial resolution and multi-color imaging capabilities simultaneously. The device achieved a spatial resolution of 2 mm and an imaging speed of 1 frame/s. The scanning depth is 8 mm. It was used to scan a 22 cm x 22 cm area of a human-shaped phantom, verifying its potential for scanning humans. The ability of the device to identify and quantify SPIOs was validated using mice breast tumors. The quantitative accuracy during simultaneous imaging was determined to be 96.58%. Due to its innovative structural design and rapid frequency conversion method, the RFC-MPI device exhibits excellent in vivo imaging performance. Both simulation and phantom experiments have verified the effectiveness of the proposed method. The hand-held RFC-MPI device can effectively improve the spatial resolution and quantitative accuracy of multi-color MPI, laying the foundation for future clinical applications.