In this paper, a finite-time convergent continuous action iterated dilemma (CAID) with topological optimization is proposed to overcome the limitations of traditional methods. Asymptotic stability in ...traditional CAID does not provide information about the rate of convergence or the dynamics of the system in the finite time. There are no effective methods to analyze its convergence time in previous works. We made some efforts to solve these problems. Firstly, CAID is proposed by enriching the players’ strategies as continuous, which means the player can choose an intermediate state between cooperation and defection. And discount rate is considered to imitate that players cannot learn accurately based on strategic differences. Then, to analyze the convergence time of CAID, a finite-time convergent analysis based on the Lyapunov function is introduced. Furthermore, the optimal communication topology generation method based on the Deep Q-learning (DQN) is proposed to explore a better game structure. At last, the simulation shows the effectiveness of the proposed method.
•The dynamic model of Continuous Action Iterated Dilemma (CAID) with continuous strategy is more realistic.•The convergence time of CAID is analyzed by proposed finite-time convergent analysis method based on the Lyapunov function.•The optimal communication topology generation method based on DQN is proposed to enhance the game structure.
In current 3D printing technologies, it remains a great challenge to print continuous carbon fibre reinforced composites with complex shapes and high mechanical performances. The main reason lies in ...the limitation of printing path design, which cannot guarantee to print carbon fibres along load transmission paths of composite parts. Here we address this issue by proposing an ingenious path-designed 3D (PD-3D) printing approach that considers the load transmission path and anisotropic property of the continuous carbon fibre reinforced filament. Complex structures of carbon fibre reinforced composites, with enhanced lightweight, were demonstrated. Such structures of carbon fibres paving along load transmission paths, greatly reduce stress concentration and achieve a quasi-isotropic performance. By comparing printed specimens with drilled holes and semicircles, the PD-3D printed specimens with holes and semicircles are 67.5% and 62.4% higher in tensile and flexural strength, respectively. And the strength to weight ratio of the tensile and flexural specimens also increase by 55.1% and 35.2%, compared with the drilled ones.
Based on the local resonance effect of elastic waves, three single-phase acoustic metamaterials are proposed in this paper. Based on the finite element method and Bloch's theorem, the energy band ...structure diagrams and vibration modes are plotted, and the band gap properties and band gap opening mechanism of these structures are explored. New structures possessing lower frequency band gaps are obtained by topological optimization. The transmission curves verify the accuracy of the band gap and the vibration attenuation ability of the structure. Finally, the structural parameters were adjusted and the effect of each parameter change on the band gap characteristics was analyzed. The results show that the proposed structure has a maximum band gap coverage of 72.4 % and a strongest attenuation peak of less than −400 (dB) due to the occurrence of a local resonance. This paper provides a methodology for analyzing the vibration and noise reduction performance of single-phase material phononic crystals, as well as a three-dimensional phononic crystal with potential for practical applications.
•Based on the local resonance effect, we obtained three models by adjusting the model structure.•Four forms of vibration that open the bandgap have been discovered.•Verification of bandgap accuracy based on transmission curves and stress clouds.•The analytical and validation methods in this paper provide ideas for studying the damping characteristics of 3D models.
•Optimal design of various periodic unit cells aiming at high thermal conductivity.•Schemes to modulate porous microstructure based on topology optimization.•Computational and experimental validation ...of effective thermal conductivity with error less than 10 %.
Porous structures are lightweight and thus possess tailorable thermophysical properties through topological design. A multi-constraint topology optimization scheme is developed for designing 2D periodic lattice material with controllable porosity and optimal thermal conductivity. The porosity, pore size and specific surface area are modulated by imposing local density constraints, and thus the structure-determined thermal conductivity can be systematically investigated. The isotropic porous structures after optimization show effective thermal conductivity close to the Hashin-Shtrikman theoretical bound. The specific surface area of base cell is enlarged with imposing local density constraint. In addition, microstructure with anisotropic thermal conductivity can be also obtained. The samples of lattice structure are additively manufactured via selective laser melting, and the thermal conductivities are experimentally validated with deviation within 10 %. The proposed porous structures with targeted porosity have potential application in skeleton embedded with phase change materials.
Recent works introduced topology optimization in the design of robots, but the proposed methodologies led to a local optimization of the performance. Moreover, most of performance indices used are ...not in strong relation with easy-to-understand technological requirements.
We propose a methodology that is able to perform a topology optimization for robots, valid globally in the workspace or for a set of given trajectories, and which is based on the use of technology-oriented performance criteria. In order to enforce the chosen performance indices to be valid globally, optimal robot configurations or trajectories for which extreme performance will be attained are computed, and iteratively updated.
In order to decrease the computational time associated with these performance indices, we exploit the structure of the elastic models in order to reduce their computational complexity.
Finally, we use an optimization algorithm called the Linearization Method which gives results in a computational time equivalent to standard topology optimization algorithms, but its implementation is less complex and makes it quite easy to perform modification or improvement.
The methodology is applied for the design of a five-bar mechanism. We show that our approach leaded to a robust optimization of the robot performance over the whole workspace.
Lattice and porous structures have attracted attention in scientific literature due to the development of 3D printers that facilitate their manufacturing. A thorough understanding of the mechanical ...behaviour of these structures is necessary. In this work, several lattice and porous structures are analysed using the finite element method. Eleven configurations have been studied using periodic boundary conditions, in order to numerically estimate their elastic mechanical properties (Young’s modulus, shear modulus and Poisson’s ratio) as a function of the structure porosity. In addition, a tensile fracture test has been modelled to analyse the predicted fracture pattern as well as the stress-strain curve for each structure. It is shown that structures based on spherical holes distributions lead to stiffer structures in tensile and shear conditions. The distribution of cavities has a strong influence on the mechanical behaviour. The square distribution improves stiffness, while the hexagonal distribution improves the shear modulus. Random distributions clearly decrease the stiffness and strength of the structure, although the damage in these structures is more progressive. Therefore, this work provides a comparative study to assess the influence of the lattice topological structure on some mechanical properties of interest in structural engineering, as a function of porosity.
Phononic crystals (PnCs) are artificially made materials composed of periodically arranged structures capable of manipulating acoustic/elastic wave propagation characteristics. In this paper, an ...improved fast plane wave expansion method (IFPWEM) is developed to obtain the band structures of PnCs. In the method presented, the continuity of the algorithm has been improved by eliminating the jump discontinuity points as well as decreasing the number of wave vectors used. Implementing these changes results in increased computational efficiency when compared to the traditional fast plane wave expansion method (FPWEM). In order to increase the band gap width produced by the PnCs, an adaptive genetic algorithm is adopted to optimize the PnCs structural topology for in-plane wave mode (xy mode). The numerical results yielded from optimization of two-dimension (2D) PnCs with a symmetric square lattice microstructure verifies that the efficiency of the IFPWEM is significantly greater than the conventional FPWEM and finite element methods.
•AGA-IFPWEM is proposed for topology optimization of PnCs.•IFPWEM is introduced to analyze the band structures of PnCs.•Wave vectors for band structure analysis decrease from 625 to 81 by IFPWEM.•AGA significantly decreases the iterative times required for convergence.
Advances introduced by additive manufacturing have significantly improved the ability to tailor scaffold architecture, enhancing the control over microstructural features. This has led to a growing ...interest in the development of innovative scaffold designs, as testified by the increasing amount of research activities devoted to the understanding of the correlation between topological features of scaffolds and their resulting properties, in order to find architectures capable of optimal trade-off between often conflicting requirements (such as biological and mechanical ones). The main aim of this paper is to provide a review and propose a classification of existing methodologies for scaffold design and optimization in order to address key issues and help in deciphering the complex link between design criteria and resulting scaffold properties.
Topology optimization of an ATV wheel hub Karthikeyan, K; Kishore, R; Jeeva, K ...
Journal of physics. Conference series,
09/2021, Letnik:
2027, Številka:
1
Journal Article
Recenzirano
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Abstract
The article is based on the Topology Optimization of an ATV Wheel Hub. So, we use this methodology to reduce the unwanted material of the All-Terrain Vehicle(ATV) Wheel HUB and to reduce the ...weight. ATV is mainly designed for a competition, where the Hub is used to connect the wheel to chassis via steering knuckles and arm linkages. Hub plays a vital role in the ATV. So, designing of hub should be in proper dimensions. The hub material is designed with a help of SOLIDWORKS. And it was analysed by SolidWorks simulation. The material used for a hub is Aluminium alloy 6063-T6.
The work explores a specific scenario for structural computational optimization based on the following elements: (a) a relaxed optimization setting considering the ersatz (bi-material) approximation, ...(b) a treatment based on a non-smoothed characteristic function field as a topological design variable, (c) the consistent derivation of a relaxed topological derivative whose determination is simple, general and efficient, (d) formulation of the overall increasing cost function topological sensitivity as a suitable optimality criterion, and (e) consideration of a pseudo-time framework for the problem solution, ruled by the problem constraint evolution.
In this setting, it is shown that the optimization problem can be analytically solved in a variational framework, leading to, nonlinear, closed-form algebraic solutions for the characteristic function, which are then solved, in every time-step, via fixed point methods based on a pseudo-energy cutting algorithm combined with the exact fulfillment of the constraint, at every iteration of the non-linear algorithm, via a bisection method. The issue of the ill-posedness (mesh dependency) of the topological solution, is then easily solved via a Laplacian smoothing of that pseudo-energy.
In the aforementioned context, a number of (3D) topological structural optimization benchmarks are solved, and the solutions obtained with the explored closed-form solution method, are analyzed, and compared, with their solution through an alternative level set method. Although the obtained results, in terms of the cost function and topology designs, are very similar in both methods, the associated computational cost is about five times smaller in the closed-form solution method this possibly being one of its advantages. Some comments, about the possible application of the method to other topological optimization problems, as well as envisaged modifications of the explored method to improve its performance close the work.
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