The realization of unidirectional acoustic transmission (UAT) has recently aroused great attention owing to the versatile possibility in acoustics-based applications. This paper extends the ...bi-directional evolutionary structural optimization (BESO) method to the design of phononic crystal (PC) for achieving UAT. The optimization objective is to enlarge the minimum imaginary part of wave vectors along Γ-X while keep that along Γ-M less than the constraint value. We systematically studied the design of symmetric and asymmetric PCs at various frequencies. Numerical examples demonstrate that the proposed optimization algorithm is effective for creating the partial band gap at the specified frequency. The UAT with high rectifying efficiency is then successfully realized by placing the optimized PC in a bend wave guide. The results also show that the asymmetric PCs are more favorable for the design of broadband UAT devices compared with symmetric ones.
Additive Manufacturing (AM) has become popular for rapid prototyping and it is presently widely used in different branches of industry because of its advantages such as freedom of design, mass ...customization, waste minimization and the ability to manufacture complex shape. AM is the process of making 3D object from computer model data by depositing of material layer by layer. Topology optimization is iterative modifying the shape and optimizing material within a given designs space for load, boundary condition thus leading to weight reduction of components. Thus, to form lightweight components which have great advantage where energy consumption is minimal, topology optimization is used. Reducing weight and decreasing the material usage while keeping the product functions are the main challenges. Studies on the integration of the topology optimization and additive manufacturing, specifically mass reduction attract considerable attention. The topology optimization process is employed in this case study, to redesign a lightweight automotive brake pedal to show the potential of topology optimized design for additive manufacturing. As a result of this study 54.07% weight reduction was achieved in the total mass. The thermo- mechanical analysis for additive manufacturing showed that the part without topological optimization 108 MPa of stress and 1,099 mm of displacement were obtained and after optimization they were 196,1 MPa and 1,295 mm, respectively.
The periodic truss structures in mechanical metamaterials have received widespread attention, yet stress concentration at nodes promotes the failure of truss structures, in particular under tension ...load. Here we report that tensile properties (in particular, ductility) of truss structures can be remarkedly improved by replacing the surface at the node with a triply periodic minimal surface (TPMS) structure. The intrinsic stress concentration at nodes in truss lattice structure can be readily dissipated at TPMS-modified nodes and transferred to the connected ligaments, leading to the enhanced tensile ductility. Moreover, the efficacy of TPMS modification is found to be correlated with the node coordination number, where lattice structures with a high coordination number of nodes possess better property improvements. The role of TPMS nodes on stress transfer and deformation de-localization behaviors is well interpreted by the in-situ microstructural analyses as well as finite element modeling simulations.
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Phononic band gap crystals offer great flexibility for manipulating elastic waves and can be used for many applications. The occurrence of band gaps highly depends on the spatial ...distribution of material phases in phononic crystals. This paper investigates topology optimization of two-dimensional (2D) solid/solid hexagonal-latticed phononic crystals with sixfold symmetry for maximizing specified band gaps. The optimization algorithm based on the bi-directional evolutionary structural optimization (BESO) method is established and verified by numerical examples. Various novel patterns with large band gaps for out-of-plane and in-plane waves are obtained and optimized solutions are discussed and compared with those of square-latticed ones. Based on the optimized solutions for out-of-plane waves and in-plane waves, the proposed method is extended to the design of the complete band gaps. The transmission analysis of the finite phononic structure formed by optimized phononic crystals shows that out-of-plane waves and in-plane waves can be transmitted or prohibited, which agrees well with the obtained band gaps in optimization. The further improvement of the proposed BESO method is also recommended.
Microwave absorption plays an important role on many aspects such as stealth technologies and electromagnetic compatibility. In this work, topological optimization is applied for the proposed ...laminate metastructure (LM) to achieve broadband and wide incident-angle microwave absorption. A new and efficient version of genetic algorithms (GA), namely the large mutation genetic algorithms (LMGA) is introduced in the bi-directional evolutionary optimization (BEO) methodology which is distinguishing from the traditional bi-directional evolutionary structural optimization (BESO). Topological optimization for patterned resistive films and size optimization for spacer thickness are integrated in the program. The optimized two-dimensional patterns of the metasurface are given. The thickness optimization range is limited below 4 mm to reduce the total thickness of LM. The optimized and fabricated specimen achieves −10dB absorption bandwidth in 2.0–22.9 GHz with total thickness of 16.05 mm, small areal density of 4.19 kg/m2 and equivalent flexural strength of 23.12 MPa. A three-stage nonlinear model on the bending and buckling of LM is given, and the experimental and theoretical deflection-load curves match well. The proposed LM achieves multifunctional features of broadband microwave absorption and effective mechanical resistance.
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It is challenging to extract satisfactory building outlines from LiDAR data due to the unorganized point cloud and complex building shapes. To solve the issues, a method using adaptive tracing alpha ...shapes (ATAS) and contextual topological optimization is proposed. First, the ATAS method is used to extract sequential boundary points. After that, a method based on point cloud distribution analysis is developed to obtain building dominant directions and line segments of outlines. Finally, regularized outlines are obtained by adjusting all line segments simultaneously under the framework of global energy optimization that considers the geometric errors and contextual geometric relationships between adjacent line segments. Experimental results verify that the proposed ATAS method can efficiently extract sequential boundary points with a minimum 98.49% correctness. In addition, the extracted outlines are attractive and the minimum values of the RMSE, PoLiS, and RCC metrics of the extracted outlines are 0.48 m, 0.44 m, and 0.31 m, respectively, showing the effectiveness of the proposed method.
•Adaptive tracing alpha shapes method (ATAS) is proposed to efficiently extract sequential boundary points directly from unorganized building point clouds with complex shapes, without pre-processing (e.g., triangulation, gridding).•A method based on point cloud distribution analysis is proposed to detect accurate and reliable building dominant directions, which is beneficial to subsequent outline extraction.•The proposed method can extract smooth and attractive outlines from complex buildings by formulating outline regularization as an optimal labeling problem under the framework of global energy optimization, which balances geometric errors of boundary points and contextual geometric relationships between adjacent line segments.
•Artificial corals were designed by minimizing resistance to matter interchange.•External morphology of the coral was simulated with an iterative design domain.•The function of folds was revealed for ...providing coverage and obtaining nutrients.•Prototypes of poriferous designs were made from biologically compatible materials.
This paper presents a study of the morphogenesis of brain corals based on an experimental investigation and a topological optimization method. The resistance to matter interchange was employed to allocate the optimal space for the growth of polyp colonies from the perspective of topological optimization, where the optimized structures are those of natural brain corals. Computational fluid dynamics simulations revealed that these complicated structures can provide shelter to protect polyps from ocean currents. A reverse mold was prepared from silica gel and used to cast models from mixtures of cement and calcium carbonate, where the mixture ratio was determined based on compressive strength and biocompatibility. Based on an acid corrosion experiment, the matter interchange capability was verified. This study also proved that the many folds in the structure of brain corals contribute to the circulation of seawater, thus maintaining the concentration of nutrients and hindering the deposition of harmful substances. This paper establishes an innovative methodology for the creation of artificial brain corals, which is important for environmental restoration.
•Topological optimization of the sole to reduce material wastage while improving both its aesthetics and ecological impact.•Feet’s plantar pressure maps taken from 3 participants provide ...differentiated weight distribution of each foot.•Sole personalization according the plantar pressure maps for each foot.•Possibility to obtain the best least material design according to the feet’s pressure.
Innovative technologies are shaping the future of product development in many industries. From the wide range of applications apparel industry as garments, footwear and accessories has involved advanced technologies in different steps of product development. The focus of companies is quality and fit of products, especially for footwear products, where fit is one of the most important elements for the wearer. This is strongly related with comfort and poor fit leads to foot injuries. Considering this fact, a case study of different steps for shoe designing according to individual foot shape will be presented. Taking into consideration the aesthetics of the sole and in a more sustainable view, through topological optimization reducing of material wastage for sole production will be presented. By means of the topological optimization in the shoe design process, sole optimization is realized. As a part of personalization, feet’s plantar pressure maps taken from 3 participants gave a better explanation of weight distribution of each foot. Following, sole personalization according the plantar pressure maps for each foot gives the possibility to obtain the best least material design according to the feet’s pressure while maintaining biomechanical performance and aesthetics.
Topological optimization of the “Earring” element Kamardina, Natalia V.; Guseynov, Ruslan M.; Danilov, Igor K. ...
Vestnik Rossiĭskogo universiteta druzhby narodov. Serii͡a︡ Inzhenernye issledovanii͡a,
12/2020, Letnik:
21, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In recent decades, computer technologies and software such as computer-aided design (CAD) have been actively developing. Thanks to this, modern machine-building enterprises increase the reliability ...and quality of their products while reducing their weight and complexity of manufacturing. In order to meet numerous requirements, leading companies are increasingly using topological optimization tools at various design stages. The use of this method for effective product design is growing rapidly, due to the continuously increasing computing power of computers and software capabilities. Modern software for topological optimization allows to design the shape of the part from scratch, setting only the conditions for fixing and touching surfaces, and also allows to improve existing structures by reducing their weight based on the set restrictions (equal strength with the original part, equal deformation, preservation of natural frequency, etc.). However, the result of topological optimization is often a complex spatial structure. Using the example of the Earring element, a topological optimization of the structure was performed to ensure that the strength requirements were met and that the minimum mass was obtained. As a result of optimization, the design of a reduced weight compared to the prototype is obtained. The results of the verification calculation showed the sufficiency of the values of the strength reserves of the final design of the Earring.
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