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Lightweight Design of Multi-Objective Topology for a Large-Aperture Space Mirror
摘要： For a large-aperture space telescope, one of the key techniques is the method for designing the lightweight primary mirror assembly (PMA). In order to minimize the mirror surface error under axial gravity, lateral gravity, and polishing pressure at the same time, a method for topology optimization with multi-objective function combined with parametric optimization is introduced in this paper. The weighted compliance minimum is selected as the objective function to maximum the mirror structural stiffness. Then sensitivity analysis method and size optimization are used to determine the mirror structure parameters. Compared with two types of commonly used lightweight configurations, the new configuration design shows obvious superiority. In addition, the surface figure root mean square (RMS) of the mirror mounted by given bipod flexure (BF) under 1 g lateral gravity is minimized only with a value of 3.58 nm, which proves the effectiveness of the design method proposed in this paper.
关键词： lightweight structure,space mirror,multi-objective topology optimization,sensitivity analysis
更新于2025-09-23 15:23:52
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Design of a distributed compliant mechanism using spring-lever model and topology optimization for piezoelectrically actuated flapping wings
摘要： We present a distributed compliant mechanism, which acts like a transmission between a flapping wing of a micro air vehicle and a laminated piezoelectric actuator. The piezoelectric bimorph actuator is connected in cantilever configuration with the compliant mechanism at its free end. The mechanism takes translational deflection at its input from the piezoelectric actuator to provide angular deflection at its output, which causes flapping. We used spring-lever model and topology optimization to obtain the design of the mechanism. The design of the mechanism has been finalized by analyzing the design considering beam model with geometric nonlinearity. The final mechanism is a planar structure of 1 mm thickness and 40 mm × 24 mm in-plane footprint. The input stiffness of the compliant mechanism is 711 N/m and the output torsional stiffness is 0.014 Nm/rad. The compliant mechanism is tested with a piezoelectric bimorph actuator. The mechanism takes ±1 mm deflection with ±0.2 N block force at 30 Hz as an input and produces ±6° flap angle at 30 Hz as an output. The first fundamental frequency of the mechanism is 391 Hz, which is almost 13 times greater than our assumed wing flapping frequency 30 Hz. The final mechanism is prototyped with a 3D printer using VeroWhitePlus RGD835 material and tested with a piezoelectric bimorph actuator using a bench-top experimental set-up.
关键词： Mechanism,flapping,piezo-actuated flapping mechanism,flapping wing micro air vehicle,spring-lever model,distributed compliant mechanism,topology optimization
更新于2025-09-23 15:22:29
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A methodology for topology optimization based on level set method and its application to piezoelectric energy harvester design
摘要： Compared to a density based procedure, the level set method can acquire a clear boundary without any intermediate density elements, and has become a topical issue in topology optimization studies. In this method, the material properties of the discretized elements are usually defined as the design variables, giving rise to the so called discrete or sawtooth topologies. In this paper, a topology optimization methodology based on level-set method (LSM) and radial basis function (RBF) is proposed. To enhance the performance of the LSM, an improved material interpolation model is proposed. The RBF based post-processor is proposed to smooth the preliminary optimized topology. The proposed method is applied to the topology design of a piezoelectric energy harvester. The effect of different penalization factors is compared and analyzed. The numerical results validate the feasibility and effectiveness of the proposed method.
关键词： Coupled problems,topology optimization,level set method
更新于2025-09-23 15:22:29
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[SEMA SIMAI Springer Series] Recent Advances in Differential Equations and Applications Volume 18 || Optimal Design of Piezoelectric Microactuators: Linear vs Non-linear Modeling
摘要： The main point of this work is the comparison between linear and geometrically non-linear elasticity modeling in the field of piezoelectric actuators fabricated at the micro-scale. Manufacturing limitations such as non-symmetrical lamination of the structure or minimum length scale are taken into account during the optimization process. The robust approach implemented in the problem also reduces the sensitivity of the designs to small manufacturing errors.
关键词： Large displacements,Electrode profile,Piezoelectric actuators,Heterogeneous bimorph,Topology optimization
更新于2025-09-23 15:22:29
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Topology optimization of flextensional piezoelectric actuators with active control law
摘要： This work deals with the concept of Topology Optimization Method (TOM) applied to the design of a flextensional piezoelectric actuator (FPEA) targeting vibration attenuation of its dynamic response. On these actuators the piezoceramic shape is usually fixed and it is more advantageous to optimize the host structure topology. The flextensional actuator is formed by two piezo-ceramic layers that act as a sensor and an actuator coupled with a constant gain active velocity feedback control law (AVFC). The optimization procedure is fully described and implemented, with no simplification for the piezo-ceramic AVFC introduced to the model acts by modifying the damping matrix according to the measurements of the state variables of the system in time-domain. The dynamic equation analyzed throughout the response for the rectangular four-noded finite element (FE) analysis is obtained by the Newmark’s time-integration method, which is applied to the physical equation and to the adjoint equation needed for the sensitivity analysis. A gradient-based optimization method is applied to minimize the response signal energy of the FPEA under a transient mechanical load. Results are obtained for different control gain values to evaluate their influence on the final topology. The optimized host structure material topology for the nc-nodes model is compared with the collapsed nodes (c-nodes) model. In addition, the nc-nodes model is useful to future developments that intends to provide an external circuit to this FPEA structure aiming to intensify the AVFC damping effect.
关键词： Topology Optimization Method,Time domain transient analysis,Flextensional Piezoactuator,Active control law,Non-collapsed piezoelectric nodes
更新于2025-09-23 15:22:29
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Material distributive topology design of UWB antenna using parallel computation of improved BPSO with FDTD
摘要： In this article, the material distributive topology-based design optimization of ultra-wide band (UWB) antenna is proposed by using improved binary particle swarm optimization (BPSO) with finite difference time domain (FDTD) method. In the improved BPSO implementation, the velocity of each particle is calculated based on complete set of bits of particle position vector. The V-shaped transfer function is employed to transform all real values of velocities to values in the interval [0,1]. The fitness function of all the particles in BPSO algorithm are computed parallely by using FDTD simulation. The usage of FDTD and the parallel computation helps in analyzing the broadband frequency characteristics of the antenna with a single simulation run. The return loss of the optimized UWB antenna obtained from FDTD, Computer Simulation Technology (CST) simulation and practical measurement are in good agreement and show good impedance matching.
关键词： UWB antenna,finite difference time domain (FDTD) method,topology optimization,Binary particle swarm optimization (BPSO)
更新于2025-09-23 15:21:21
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Topology Optimization-Based Inverse Design of Plasmonic Nanodimer with Maximum Near-Field Enhancement
摘要： The near-field enhancement factor is one of the most significant parameters to evaluate the performance of plasmonic nanostructures. Numerous efforts have been made to maximize the enhancement factor through optimizing the size, shape, and spatial arrangement of metallic nanostructures with simple geometries, such as disk, triangle, and rod. This work implements topology optimization to inversely design a metallic nanoparticle dimer with the goal of optimizing the near-field enhancement factor in its sub-10 nm gap. By optimizing the material layout within a given design space, the topology optimization algorithm results in a plasmonic nanodimer of two heart-shaped particles having both convex and concave features. Full-wave electromagnetic analysis reveals that the largest near-field enhancement in the heart-shaped nanoparticle dimer is originated from the greatest concentration of surface charges at the nano-heart apex. Inversely designed heart-, bowtie-, and disk-shaped nanodimers are fabricated by using focused helium ion beam milling with a “sketch and peel” strategy, and their near-field enhancement performances are characterized with nonlinear optical spectroscopies at the single-particle level. Indeed, the heart-shaped nanodimer exhibits much stronger signal intensities than the other two structures. The present work corroborates the validity and effectiveness of topology optimization-based inverse design in achieving desired plasmonic functionalities.
关键词： topology optimization,near-field enhancement,plasmonic nanostructures,inverse design,nonlinear optics
更新于2025-09-23 15:21:01
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Designing photonic materials with complete band gaps by topology optimization
摘要： Photonic materials may exhibit the propagation of electromagnetic waves is totally prohibited. To achieve a complete photonic band gap (CPBG) for transverse magnetic (TM) and transverse electric (TE) modes, the bi-directional evolutionary structure optimization (BESO) method originated from structural design is extended for this purpose. The optimization problem is formulated with maximizing the minimum imaginary part of complex wave vectors for TM and TE modes. According to sensitivity analysis, the material distribution within the primitive unit cell of photonic materials is adjusted step by step so as to enlarge the minimum imaginary part of wave vectors. In doing so, the CPBG at the specific frequency is obtained at the desired frequency, and the optimized structures of photonic materials with novel topological patterns are achieved. Numerical examples demonstrate that the effectiveness of the proposed topology optimization method for opening the CPBGs at various specified frequencies, which is of significance in controlling the propagation of electromagnetic waves of any polarization.
关键词： Topology optimization,Complete band gap,Evanescent waves,Photonic materials
更新于2025-09-23 15:21:01
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Maximizing the quality factor to mode volume ratio for ultra-small photonic crystal cavities
摘要： Small manufacturing-tolerant photonic crystal cavities are systematically designed using topology optimization to enhance the ratio between the quality factor and mode volume, Q/V. For relaxed manufacturing tolerance, a cavity with a bow-tie shape is obtained which confines light beyond the diffraction limit into a deep-subwavelength volume. Imposition of a small manufacturing tolerance still results in efficient designs, however, with diffraction-limited confinement. Inspired by numerical results, an elliptic ring grating cavity concept is extracted via geometric fitting. Numerical evaluations demonstrate that for small sizes, topology-optimized cavities enhance the Q/V-ratio by up to two orders of magnitude relative to standard L1 cavities and more than one order of magnitude relative to shape-optimized L1 cavities. An increase in cavity size can enhance the Q/V-ratio by an increase in the Q-factor without a significant increase in V. Comparison between optimized and reference cavities illustrates that significant reduction of V requires big topological changes in the cavity.
关键词： topology optimization,mode volume,light-matter interaction,photonic crystal cavities,quality factor
更新于2025-09-16 10:30:52