Structural Configuration Design Research Articles

Research on the Structural Design of a Pressurized Cabin for Civil High-Speed Rotorcraft and the Multi-Dimensional Comprehensive Evaluation Method

For civil high-speed rotorcraft designed to operate at specific cruising altitudes, this study proposes nine structural design schemes for pressurized cabins. These schemes integrate commonly used materials and processing technologies in the aviation industry with advanced PRSEUS (Pultruded Rod Stitched Efficient Unitized Structure) technology. An analysis of the structural composition reveals that frames constitute 8–19% of the total structural weight, while stringers and beams make up 15–50%, and skins account for 11–25%, with thicknesses ranging from 1.0 mm to 2.0 mm. The separating interface of the pressurized cabin contributes 4–29% of the total structural weight. The weight distribution of each component in the pressurized cabin structure varies significantly depending on the chosen materials and processing technologies. Utilizing the Analytic Hierarchy Process (AHP), along with Gray Relational Analysis (GRA) and Dempster–Shafer (D-S) evidence theory, this study compares the simulation results of the nine schemes across multiple dimensions. The findings indicate that the configuration combining 7075 aluminum alloy and T300 composite material has the greatest advantages in terms of the high structural reliability of the configuration, light weight, mature processing technology, and low production cost. This comprehensive evaluation method quantitatively analyzes the factors influencing the structural configuration design of the pressurized cabin for civil high-speed rotorcraft, offering a valuable reference for the design of similar structures in related fields.

Multi‐physical honeycomb metastructure fabricated by fused deposition modeling with broadband radar absorption and mechanical resistance for drones

AbstractComplex structural configuration design is necessary for dielectric‐magnetic lossy composites to achieved broadband microwave absorption in civil and defense applications. Based on the unique space filling characteristic of fractal structure, the honeycomb metastructure can possess microwave absorption and mechanical resistance. However, traditional molding technique was difficult to realize complex shape of metastructure. Herein, the dielectric‐magnetic filament with different concentration of carbonyl iron particles was fabricated by high‐temperature extrusion process. The multi‐physical honeycomb metastructure with gradient layers was printed by fused deposition modeling (FDM) in a large size. The printed dielectric‐magnetic samples exhibited strong dielectric‐magnetic loss with high printing quality. The honeycomb metastructure achieved broadband microwave absorption in the −10 dB bandwidth of 9.6–18 GHz with tensile strength of 31 MPa. The results indicate that FDM is useful to fabricate metastructure with complex shape for broadband microwave absorption. The dielectric‐magnetic properties of filament are magnified by metastructure design. The proposed design‐fabrication process is promising for functional structure realization with complex shape in the future.Highlights1. Magnetic filament was fabricated for functional 3D printing.2. Structural magnetic dissipation mechanism for microwave was presented.3. Magnetic metastructure was designed and printed for broadband absorption.4. Integrated design of mechanical and electromagnetic function was presented.5. Structural absorption effect of honeycomb metastructure was revealed.

Evaluation Model of Product Shape Design Scheme Based on Fuzzy Genetic Algorithm Mining Spatial Association Rules

Put forward a kind of association rules mining method based on fuzzy genetic algorithm, this approach by building a mining model, the association rules and fuzzy genetic algorithm fuses in together, and then given to the fitness function of the mining space, and uses threshold to limit the fuzzy genetic algorithm will cross distribution and compile the fitness function, the improved method excavation stability is strong, the mining accuracy is high. The clustering analysis method of multidimensional fuzzy genetic algorithm mapping association network is studied, and the multidimensional module layout target is analyzed by using fuzzy hierarchical analysis technology and improved genetic algorithm combined with the clustering target of each angle, and the module division of each angle is realized. The main structure of the product is constructed with process model as the integration framework, style as the organization form, and feature list as the expression mechanism. The product characteristics based on fuzzy genetic algorithm are studied, the main structure configuration design process model mapping relation analysis, combined with the main structure of the joint model, together to achieve the fuzzy genetic algorithm (GA) variant design of fine-grained axiomatic mode, based on the associated network building and integration of new product design process, product structure of multidimensional optimization problem is solved.

Stiffness modulation for soft robot joint via lattice structure configuration design

Soft materials have been applied on the soft robots built with high deformation and compliance. Additive manufacturing (AM) technology has the ability to fabricate functional soft materials or structures. However, soft robots generally have shortages in strength to manipulate relatively heavy objects. This paper proposes a novel concept on the application of lattice structure configuration for the lightweight functional spherical joint of soft robotics with variable stiffness modulation. A novel active spherical joint driven by air pressure is mainly composed of a rigid ball and soft porous socket. The stiffness can be adjusted by changing air pressure in the soft socket. In order to obtain a high-speed response performance and large-scale linear stiffness, the socket is divided into inner and outer layers. Parametric uniform strut-based lattice structures are populated within the inner layer of the socket to guarantee the flow of air. Trimmed TPMS-based lattice structures are infilled within the outer to keep the stable external shape of the socket. The manufacturability for two lattice structure configurations is also analyzed. In order to achieve a linear variable stiffness, the type and size of lattice unit cells and the thickness of lattice struts can be changed parametrically.

An 89-line code for geometrically nonlinear topology optimization written in FreeFEM

Topology optimization has emerged as a powerful tool for structural configuration design. To further promote the development of topology optimization, many computer programs have been published for educational purposes over the past decades. However, most of the computer programs are constructed based on a linear assumption. This paper presents an 89-line code for nonlinear topology optimization written in FreeFEM based on the popular SIMP (solid isotropic material with penalization) method. Excluding thirteen lines which are used for explanation, only 76 lines are needed for the initialization of the design parameters, nonlinear finite element analysis, sensitivity calculation, and updated design variables. Different design problems can be solved by modifying several lines in the proposed program. The complete program is given in the Appendix and is intended for educational purposes only.

CAVITY MODES IN DUAL PHONONIC AND PHOTONIC CRYSTAL WITH WIDE ABSOLUTE BANDGAP

In this paper, we discuss theoretically the simultaneous existence of dual phononic and photonic band gaps and cavity modes in a PhoXonic crystal. The cavity is created in the center of a square lattice PhoXonic crystal made from silicon using the one-missing-holes point defect (L1). Following the design, dispersion diagrams and the resonant frequency are numerically analyzed by the finite elements method (FEM). Optimization of the PhoXonic crystal design by modulating the structure parameter yields a complete phononic gap together with a photonic gap. Furthermore, we demonstrate the existence of the largest number of cavity modes with a high quality factor of 10 5 . This structure configuration design shows considerable promise as regards the simultaneous confinement of acoustic and optical waves and thus more attractive for experimental observation of optomechanical coupling.

Configuration design of structures under dynamic constraints by a hybrid bat algorithm and teaching–learning based optimization

Optimal design of steel trusses is an interesting task due to existence of many alternatives for their spatial configuration. Meanwhile, performance criteria have enforced their vibration to maintain within certain limits. The present work concerns implementation of frequency constraints as a common approach to implicitly satisfy such practical requirements. The problem objective is to minimize the cost of steel material by simultaneous size and geometry optimization of trusses. In this regard teaching–learning-based-optimization and bat-algorithm are hybridized via a new effective framework. The former acts as a global search engine, the latter provides search refinement to access higher quality solutions. Effectiveness and efficiency of the proposed hybrid method are evaluated using a number of bridge and space structures via comparison with literature works. Numerical simulations show enhanced effectiveness and less deviation about final optimum design as a result of implementing the proposed hybridization.

Optimization of Q-factor in nonlinear planar photonic crystal nanocavity incorporating hybrid silicon/polymer material

We present a novel design for a high quality (Q)-factor, nonlinear planar photonic crystal (PhC) nanocavity incorporating a silicon/polymer material that is well suited to ultrafast all-optical switching. The hybrid nanocavity is created in the centre of a triangular lattice planar PhC made from silicon using the three-missing-holes point defect (L3). It is formed by infiltrating the air hole array of the PhC with polymer and by depositing a polymer layer on top of a PhC membrane. To determine the hybrid nonlinear cavity performance, we analyze the dependence of the refractive index (RI) of the top cladding on the Q-factor and resonant wavelength. The results show that, when the top cladding RI is increased from 1.5 to 1.6, corresponding to that of polymer materials, the Q-factor decreases markedly (Q < 103). Optimization of the hybrid nonlinear silicon/polymer cavity design by modulating the structure parameters yields a high Q-factor of 54 000 with a small modal volume across the telecommunications band. In addition, the field distribution of the resonant mode indicates that the radiation loss is sufficiently small. Due to the overwhelmingly large Kerr nonlinearity of polymer over silicon, this structure configuration design shows considerable promise as regards the realization of ultrafast response speed in small-sized all-optical switching integrated devices.

Selection of manipulator system for multiple-goal task by evaluating task completion time and cost with computational time constraints

The focus of this study is on the problem of manipulator system selection for a multiple-goal task by evaluating task completion time and cost with computational time constraints. An approach integrating system selection, structural configuration design, layout design, motion planning, and relative cost calculation is proposed to solve this problem within a reasonable computational time. In the proposed approach, multiple-objective particle swarm optimization (MOPSO) is utilized to search for the appropriate manipulator system with appropriate structural configuration from a set of candidate systems. Particle swarm optimization (PSO) and the nearest neighborhood algorithm are employed in layout design and motion planning due to their high convergence speed. Three methods involving a random search algorithm are compared to the proposed approach through a simulation. The simulation is done with a set of tasks and the result shows the effectiveness of the proposed approach.

The lattice structure configuration design for stereolithography investment casting pattern using topology optimization

PurposeThe purpose of this paper is to introduce, for the first time, the topology optimization method into the lattice structure configuration design for rapid casting patterns.Design/methodology/approachA structural topology optimization procedure in combination with thermo‐mechanical finite element analysis for the lattice structure configuration design has been developed.FindingsA new mixed stress‐compliance optimization model is proposed for the strength and rigidity design. Numerical modeling about the mathematical formulation of the objective function and design constraints is established and an optimal material layout inside a given domain of the stereolithography (SL) resin pattern is found.Originality/valueVarious optimal results of lattice structure configurations are obtained numerically. By comparing the optimal designs with the existing lattice structure configurations, the newly obtained designs have shown better performances both in reducing the stress in the ceramic shell and in maintaining the stiffness of the SL pattern.

Automated structural optimization system for integrated topology and shape optimization

This paper combines previously developed techniques for image‐preprocessing and characteristic image‐interpreting together with a newly proposed automated shape‐optimization modeling technique into an integrated topology‐optimization and shape‐optimization system. As a result, structure designers are provided with an efficient and reliable automated structural optimization system (ASOS). The automated shape‐optimization modeling technique, the key technique in ASOS, uses hole‐expanding strategy, interference analysis, and hole shape‐adjusting strategy to automatically define the design variables and side constraints needed for shape optimization. This technique not only eliminates the need to manually define design variables and side constraints for shape optimization, but during the process of shape optimization also prevents interference between the interior holes and the exterior boundary. The ASOS is tested in three different structural configuration design examples.

A New Method of Structural Synthesis about the Partly-DOF Parallel Robot Mechanisms Based on the Screw Theory

In this paper, based on some disciplinarians about the configuration design of Parallel Robot Mechanisms (PRM), the theory bases was established for parallel structural configuration design by developing different types of the partly degrees of freedom (DOF) parallel configuration designs. The new method to synthesize the partly DOF parallel mechanisms, called constraint accession, is provided to the classification of kinematical chains by use of screw theory. The active kinematical chains control the necessary DOF and the passive kinematical chains control the needless ones. In this paper, the relevant active and passive kinematical chains are put forward and the constraint chains are classified in detail. It is demonstrated by an example that new configurations can be obtained by assembling different kinematical limbs.

A hybrid deterministic/stochastic optimization approach for the shape configuration design of structures

This paper presents a computer-based shape configuration design methodology to generate optimum design of specified structures satisfying the structural performance requirements and the geometric connectivity of the model. Mathematically, this problem can be categorized as a large-scale, nonconvex and nonlinear problem. The solution methods, grouped into two main categories, deterministic and stochastic approaches, require enormous computational efforts to find global optimum designs, a matter of major importance since many local suboptimal solutions can exist. In this study, two popular methods belonging to each class are examined and compared. The methods understudied are selected as the enumeration technique for deterministic approach and the simulated annealing for the stochastic method. The advantages and disadvantages of each technique are investigated. Using the best properties of each method and an algorithm for phase change between the two, a hybrid global shape optimization approach is formulated. The hybrid method is structured to combine the enumeration method for local minimization process and the simulated annealing for global minimum search phase. The hybrid method can find global optimum designs in a robust and efficient way, contrary to the signle phase solutions examined in this study. To demonstrate the hybrid method and its effectiveness, several design examples are presented.

Optimal configuration design of structures using the binary enumeration technique

This paper presents an optimization methodology for the design of structural members. The objective is to develop a fully stressed design while satisfying constraints on the maximum stress value and maintenance of the connectivity of finite elements in the model. This work is based on altering the finite element model of structure by removing or keeping elements in the discretized design. Such a problem is categorized into a large-scale, non-convex and non-linear discrete problem. Thus, it can have many local optimum solutions and it is important to develop methodologies that find global optimum solutions as opposed to local. In this study, to solve the problem, a discrete optimization technique based on enumeration method is used. To improve the computational efficiency, the non-linear design problem has been linearized. An error intensity analysis is implemented to account for the difference between the non-linear and the linearized values. To illustrate the approach, several design examples are presented and examined.

Configuration design sensitivity analysis of built‐up structures part II: Numerical method

AbstractA numerical method is presented for structural configuration design sensitivity calculations using established finite element analysis codes. The theoretical foundation of the configuration design sensitivity analysis is given in Part I of this paper1 using the continuum elasticity formulation. A linear approximation between design parameterizations and design velocity fields is derived for line and surface design components. A regular design velocity that avoids the calculation of corner terms at the boundary is implemented to show a unified configuration design sensitivity analysis. The design sensitivity analysis method is demonstrated using the post‐processing data of an existing finite element code. Configuration design sensitivity results of displacement, stress and eigenvalue performance measures are illustrated for several built‐up engineering structures.

An Integrated Environment for Structural Configuration Design

SUMMARY Structural design is a mature field of engineering. The relatively recent efforts for lightweight structures have motivated increasing use of formal mathematical optimization techniques for selecting the shape and sizes of structural members. How to obtain rigorous optimal topologies has been an elusive goal until the very recent introduction of the homogenization method. The present article describes a system for designing complete structures from only an initial space and loading specifications. A three–phase design process is followed: generate an approximate topological image with homogenization, process the image to obtain a practical realistic structure, and refine the final topology by detailed shape and size optimization. An overview of the system at its present state of development is given together with some examples.