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优化 18

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Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

《结构与土木工程前沿(英文)》 2022年 第16卷 第12期   页码 1565-1580 doi: 10.1007/s11709-022-0867-4

摘要: This study proposes a shape optimization method for K6 aluminum alloy spherical reticulated shells with gusset joints, considering geometric, material, and joint stiffness nonlinearities. The optimization procedure adopts a genetic algorithm in which the elastoplastic non-linear buckling load is selected as the objective function to be maximized. By confinement of the adjustment range of the controlling points, optimization results have enabled a path toward achieving a larger elastoplastic non-linear buckling load without changing the macroscopic shape of the structure. A numerical example is provided to demonstrate the effectiveness of the proposed method. In addition, the variation in structural performance during optimization is illustrated. Through parametric analysis, practical design tables containing the parameters of the optimized shape are obtained for aluminum alloy spherical shells with common geometric parameters. To explore the effect of material nonlinearity, the optimal shapes obtained based on considering and not considering material non-linear objective functions, the elastoplastic and elastic non-linear buckling loads, are compared.

关键词: shape optimization     aluminum alloy     spherical reticulated shell     non-linear buckling     material nonlinearity     genetic algorithm    

Topology optimization and seismic collapse assessment of shape memory alloy (SMA)-braced frames: Effectiveness

Aydin HASSANZADEH; Saber MORADI

《结构与土木工程前沿(英文)》 2022年 第16卷 第3期   页码 281-301 doi: 10.1007/s11709-022-0807-3

摘要: This paper presents a seismic topology optimization study of steel braced frames with shape memory alloy (SMA) braces. Optimal SMA-braced frames (SMA-BFs) with either Fe-based SMA or NiTi braces are determined in a performance-based seismic design context. The topology optimization is performed on 5- and 10-story SMA-BFs considering the placement, length, and cross-sectional area of SMA bracing members. Geometric, strength, and performance-based design constraints are considered in the optimization. The seismic response and collapse safety of topologically optimal SMA-BFs are assessed according to the FEMA P695 methodology. A comparative study on the optimal SMA-BFs is also presented in terms of total relative cost, collapse capacity, and peak and residual story drift. The results demonstrate that Fe-based SMA-BFs exhibit higher collapse capacity and more uniform distribution of lateral displacement over the frame height while being more cost-effective than NiTi braced frames. In addition to a lower unit price compared to NiTi, Fe-based SMAs reduce SMA material usage. In frames with Fe-based SMA braces, the SMA usage is reduced by up to 80%. The results highlight the need for using SMAs with larger recoverable strains.

关键词: topology optimization     shape memory alloy     Fe-based SMA     steel braced frames     performance-based seismic design     collapse assessment    

Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

《结构与土木工程前沿(英文)》 2019年 第13卷 第4期   页码 852-862 doi: 10.1007/s11709-019-0522-x

摘要: Due to an increased need in hydro-electricity, water storage, and flood protection, it is assumed that a series of new dams will be build throughout the world. The focus of this paper is on the non-probabilistic-based design of new arch-type dams by applying means of robust design optimization (RDO). This type of optimization takes into account uncertainties in the loads and in the material properties of the structure. As classical procedures of probabilistic-based optimization under uncertainties, such as RDO and reliability-based design optimization (RBDO), are in general computationally expensive and rely on estimates of the system’s response variance, we will not follow a full-probabilistic approach but work with predefined confidence levels. This leads to a bi-level optimization program where the volume of the dam is optimized under the worst combination of the uncertain parameters. As a result, robust and reliable designs are obtained and the result is independent from any assumptions on stochastic properties of the random variables in the model. The optimization of an arch-type dam is realized here by a robust optimization method under load uncertainty, where hydraulic and thermal loads are considered. The load uncertainty is modeled as an ellipsoidal expression. Comparing with any traditional deterministic optimization method, which only concerns the minimum objective value and offers a solution candidate close to limit-states, the RDO method provides a robust solution against uncertainty. To reduce the computational cost, a ranking strategy and an approximation model are further involved to do a preliminary screening. By this means, the robust design can generate an improved arch dam structure that ensures both safety and serviceability during its lifetime.

关键词: arch dam     shape optimization     robust optimization     load uncertainty     approximation model    

An ANN-exhaustive-listing method for optimization of multiple building shapes and envelope properties

Yaolin LIN, Wei YANG

《能源前沿(英文)》 2021年 第15卷 第2期   页码 550-563 doi: 10.1007/s11708-019-0607-1

摘要: With increasing awareness of sustainability, demands on optimized design of building shapes with a view to maximize its thermal performance have become stronger. Current research focuses more on building envelopes than shapes, and thermal comfort of building occupants has not been considered in maximizing thermal performance in building shape optimization. This paper attempts to develop an innovative ANN (artificial neural network)-exhaustive-listing method to optimize the building shapes and envelope physical properties in achieving maximum thermal performance as measured by both thermal load and comfort hour. After verified, the developed method is applied to four different building shapes in five different climate zones in China. It is found that the building shape needs to be treated separately to achieve sufficient accuracy of prediction of thermal performance and that the ANN is an accurate technique to develop models of discomfort hour with errors of less than 1.5%. It is also found that the optimal solutions favor the smallest window-to-external surface area with triple-layer low-E windows and insulation thickness of greater than 90 mm. The merit of the developed method is that it can rapidly reach the optimal solutions for most types of building shapes with more than two objective functions and large number of design variables.

关键词: ANN (artificial neural network)     exhaustive-listing     building shape     optimization     thermal load     thermal comfort    

An isogeometric numerical study of partially and fully implicit schemes for transient adjoint shape sensitivity

Zhen-Pei WANG, Zhifeng XIE, Leong Hien POH

《机械工程前沿(英文)》 2020年 第15卷 第2期   页码 279-293 doi: 10.1007/s11465-019-0575-5

摘要: In structural design optimization involving transient responses, time integration scheme plays a crucial role in sensitivity analysis because it affects the accuracy and stability of transient analysis. In this work, the influence of time integration scheme is studied numerically for the adjoint shape sensitivity analysis of two benchmark transient heat conduction problems within the framework of isogeometric analysis. It is found that (i) the explicit approach ( = 0) and semi-implicit approach with <0.5 impose a strict stability condition of the transient analysis; (ii) the implicit approach ( =1) and semi-implicit approach with > 0.5 are generally preferred for their unconditional stability; and (iii) Crank–Nicolson type approach ( =0.5) may induce a large error for large time-step sizes due to the oscillatory solutions. The numerical results also show that the time-step size does not have to be chosen to satisfy the critical conditions for all of the eigen-frequencies. It is recommended to use for unconditional stability, such that the oscillation condition is much less critical than the Crank–Nicolson scheme, and the accuracy is higher than a fully implicit approach.

关键词: isogeometric shape optimization     design-dependent boundary condition     transient heat conduction     implicit time integration     adjoint method    

Shape and topology optimization for tailoring the ratio between two flexural eigenfrequencies of atomic

Qi XIA,Tao ZHOU,Michael Yu WANG,Tielin SHI

《机械工程前沿(英文)》 2014年 第9卷 第1期   页码 50-57 doi: 10.1007/s11465-014-0286-x

摘要:

In an operation mode of atomic force microscopy that uses a higher eigenmode to determine the physical properties of material surface, the ratio between the eigenfrequency of a higher flexural eigenmode and that of the first flexural eigenmode was identified as an important parameter that affects the sensitivity and accessibility. Structure features such as cut-out are often used to tune the ratio of eigenfrequencies and to enhance the performance. However, there lacks a systematic and automatic method for tailoring the ratio. In order to deal with this issue, a shape and topology optimization problem is formulated, where the ratio between two eigenfrequencies is defined as a constraint and the area of the cantilever is maximized. The optimization problem is solved via the level set based method.

关键词: atomic force microscopy     cantilever probe     eigenfrequency     optimization    

An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memoryeffect in shape memory alloys

S. HASHEMI,H. AHMADIAN,S. MOHAMMADI

《结构与土木工程前沿(英文)》 2015年 第9卷 第4期   页码 466-477 doi: 10.1007/s11709-015-0300-3

摘要: Thermo-mechanical coupling in shape memory alloys is a very complicated phenomenon. The heat generation/absorption during forward/reverse transformation can lead to temperature-dependent variation of its mechanical behavior in the forms of superelasticity and shape memory effect. However, unlike the usual assumption, slow loading rate cannot guarantee an isothermal process. A two-dimensional thermo-mechanically coupled algorithm is proposed based on the original model of Lagoudas to efficiently model both superelasticity and shape memory effects and the influence of various strain rates, aspect ratios and boundary conditions. To implement the coupled model into a finite element code, a numerical staggered algorithm is employed. A number of simulations are performed to verify the proposed approach with available experimental and numerical data and to assess its efficiency in solving complex SMA problems.

关键词: shape memory alloy     thermo-mechanical coupling     superplasticity     shape memory effect    

A novel shape memory alloy actuated soft gripper imitated hand behavior

《机械工程前沿(英文)》 2022年 第17卷 第4期 doi: 10.1007/s11465-022-0700-8

摘要: The limited length shrinkage of shape memory alloy (SMA) wire seriously limits the motion range of SMA-based gripper. In this paper, a new soft finger without silicone gel was designed based on pre bent SMA wire, and the finger was back to its original shape by heating SMA wire, rather than relying only on heat exchange with the environment. Through imitating palm movement, a structure with adjustable spacing between fingers was made using SMA spring and rigid spring. The hook structure design at the fingertip can form self-locking to further improve the load capacity of gripper. Through the long thin rod model, the relationship of the initial pre bent angle on the bending angle and output force of the finger was analyzed. The stress-strain model of SMA spring was established for the selection of rigid spring. Three grasping modes were proposed to adapt to the weight of the objects. Through the test of the gripper, it was proved that the gripper had large bending amplitude, bending force, and response rate. The design provides a new idea for the lightweight design and convenient design of soft gripper based on SMA.

关键词: shape memory alloy (SMA)     pre bent     wire     gripper     grasping mode     lightweight    

Size and shape effects of MnFeO nanoparticles as catalysts for reductive degradation of dye pollutants

《环境科学与工程前沿(英文)》 2021年 第15卷 第5期   页码 108-171 doi: 10.1007/s11783-021-1396-4

摘要: The magnetic nanoparticles that are easy to recycle have tremendous potential as a suitable catalyst for environmental toxic dye pollutant degradation. Rationally engineering shapes and tailoring the size of nanocatalysts are regarded as an effective manner for enhancing performances. Herein, we successfully synthesized three kinds of MnFe2O4 NPs with distinctive sizes and shapes as catalysts for reductive degradation of methylene blue, rhodamine 6G, rhodamine B, and methylene orange. It was found that the catalytic activities were dependent on the size and shape of the MnFe2O4 NPs and highly related to the surface-to-volume ratio and atom arrangements. Besides, all these nanocatalysts exhibit selectivity to different organic dyes, which is beneficial for their practical application in dye pollutant treatment. Furthermore, the MnFe2O4 NPs could be readily recovered by a magnet and reused more than ten times without appreciable loss of activity. The size and shape effects of MnFe2O4 nanoparticles demonstrated in this work not only accelerate further understanding the nature of nanocatalysts but also contribute to the precise design of nanoparticles catalyst for pollutant degradation.

关键词: Dye degradation     MnFe2O4 nanoparticles     Size and shape-control    

一种将拓扑优化设计转化为增材制造结构的实现方法 Article

刘书田, 李取浩, 刘君欢, 陈文炯, 张永存

《工程(英文)》 2018年 第4卷 第2期   页码 277-285 doi: 10.1016/j.eng.2017.09.002

摘要:
拓扑优化是一种用于确定最佳结构构型以获得所需性能的功能强大的设计方法。它已被广泛用于工程领域,如航空航天和汽车行业,以提高所设计结构的性能。然而,拓扑优化和工程应用之间仍然存在着一些明显阻碍拓扑优化应用的空白。其中一个空白是如何将拓扑结果(尤其是那些使用变密度框架获得的拓扑结果)解释为参数化计算机辅助设计(CAD)模型,以为随后进行的形状优化和制造创造条件。本文提出了一种将拓扑优化结果解释为适用于增材制造的STL 模型和参数化CAD 模型的新方法。在这个方法中,我们将首先提取拓扑优化结果的骨架,以确保可以保持原有形状,并使用滤波手段来获得更加光滑的边界。经过这一过程后,拓扑优化结果边界的节点分布更密集,这将为后续的曲线拟合提供便利。该方法基于均匀B 样条曲线的曲率和曲率导数,提出了一种自适应的B 样条拟合方法,以获得满足误差要求的含最少控制点的参数化CAD 模型。通过一个案例研究对所提出的方法进行了详细的描述,并通过另外两个示例证明了所提出方法的有效性和鲁棒性。

关键词: 拓扑优化     增材制造     特征保持     自适应拟合     形状优化    

300m 级特高拱坝建设关键技术与实践

王仁坤

《工程(英文)》 2016年 第2卷 第3期   页码 350-359 doi: 10.1016/J.ENG.2016.03.012

摘要:

中国于2000 年成功建设二滩拱坝( 高240 m)以来,至2014 年年底已建成7 座坝高超过200 m 的特高拱坝,其中锦屏一级拱坝(高305 m)、小湾拱坝(高294.5 m)、溪洛渡拱坝(高285.5 m)不仅坝高达300 m 级,而且因地质条件复杂,水推力巨大,抗震要求高,在安全控制技术等方面取得了新的突破。本文主要阐述300 m 级特高拱坝的基础可利用岩体及合理建基面、体形优化设计、安全设计准则、抗震研究与抗震措施、复杂地基的典型处理、混凝土及施工期温控防裂等关键技术。

关键词: 特高拱坝     优化设计     整体安全     抗震安全     混凝土温控    

Temperature effects of shape memory alloys (SMAs) in damage control design of steel portal frames

Xiaoqun LUO, Hanbin GE, Tsutomu USAMI

《结构与土木工程前沿(英文)》 2012年 第6卷 第4期   页码 348-357 doi: 10.1007/s11709-012-0176-4

摘要: The objective of the present study is to analytically investigate temperature effects of an axial-type seismic damper made of shape memory alloys (SMAs) equipped in steel frames. Based on a modified multilinear one dimensional constitutive model of SMAs, two types of SMAs are employed, which have different stress plateau and different stress growth rate with temperature increase. Temperature effects of SMA dampers on seismic performance upgrading are discussed in three aspects: different environment temperatures; rapid loading rate induced heat generation and different SMA fractions. The analysis indicates that the effect of environment temperature should be considered for the SMA damper in steel frames. However, the rapid loading rate induced heat generation has little adverse effect.

关键词: damage control design     shape memory alloy     temperature effect    

A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

《能源前沿(英文)》 2023年 第17卷 第4期   页码 504-515 doi: 10.1007/s11708-022-0855-3

摘要: Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies. As a solid-solid phase change material, shape-memory alloys (SMAs) have the inherent advantages of leakage free, no encapsulation, negligible volume variation, as well as superior energy storage properties such as high thermal conductivity (compared with ice and paraffin) and volumetric energy density, making them excellent thermal energy storage materials. Considering these characteristics, the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle. The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2 °C at 9.85 s, which is reduced by 9.8 °C, and the energy storage efficiency of the device is 66%. The influence of initial temperature, elastocaloric materials, and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed. Since SMAs are both solid-state refrigerants and thermal energy storage materials, hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.

关键词: shape-memory alloy (SMA)     elastocaloric effect (eCE)     cooled seat     cold thermal energy storage    

板形计法的定义及实验应用

张进之,段春华,朱健勤

《中国工程科学》 2001年 第3卷 第12期   页码 47-51

摘要:

板形测控数学模型、解析板形刚度理论和板形板厚协调规律的综合称为板形计法。采用两种实验方式验证了板形计法的正确性和实用性,其一是通过轧铝板实验,计算轧机板形刚度和轧件板形刚度,由实测铝板凸度验证板形刚度方程;其二是由CVC板形控制热连轧机实测数据,用离线计算自适应系数的方法验证板形测控数学模型。

关键词: 板形计法     板形刚度方程     测控数学模型     后计算     自适应    

Calculation method on shape finding of self-anchored suspension bridge with spatial cables

Yan HAN, Zhengqing CHEN, Shidong LUO, Shankui YANG

《结构与土木工程前沿(英文)》 2009年 第3卷 第2期   页码 165-172 doi: 10.1007/s11709-009-0021-6

摘要: Based on the spatial model, a reliable and accurate calculation method on the shape finding of self-anchored suspension bridge with spatial cables was studied in this paper. On the principle that the shape of the main cables between hangers is catenary, the iteration method of calculating the shapes of the spatial main cables under the load of hanger forces was deduced. The reasonable position of the saddle was determined according to the shape and the theoretical joint point of the main cables. The shapes of the main cables at completed cable stage were calculated based on the unchanging principle of the zero-stress lengths of the main cables. By using a numerical method combining with the finite element method, one self-anchored suspension bridge with spatial cables was analyzed. The zero-stress length of the main cables, the position of the saddle, and the pre-offsetting of the saddle of the self-anchored suspension bridge were given. The reasonable shapes of the main cables at bridge completion stage and completed cable stage were presented. The results show that the shape-finding calculation method is effective and reliable.

关键词: bridge engineering     self-anchored suspension bridges     special cables     shape-finding     calculation method    

标题 作者 时间 类型 操作

Shape optimization of aluminium alloy spherical reticulated shells considering nonlinearities

Wei LIU; Lishu XU; Shaojun ZHU; Lijuan LI; Feng LIU; Zhe XIONG

期刊论文

Topology optimization and seismic collapse assessment of shape memory alloy (SMA)-braced frames: Effectiveness

Aydin HASSANZADEH; Saber MORADI

期刊论文

Shape design of arch dams under load uncertainties with robust optimization

Fengjie TAN, Tom LAHMER

期刊论文

An ANN-exhaustive-listing method for optimization of multiple building shapes and envelope properties

Yaolin LIN, Wei YANG

期刊论文

An isogeometric numerical study of partially and fully implicit schemes for transient adjoint shape sensitivity

Zhen-Pei WANG, Zhifeng XIE, Leong Hien POH

期刊论文

Shape and topology optimization for tailoring the ratio between two flexural eigenfrequencies of atomic

Qi XIA,Tao ZHOU,Michael Yu WANG,Tielin SHI

期刊论文

An extended thermo-mechanically coupled algorithm for simulation of superelasticity and shape memoryeffect in shape memory alloys

S. HASHEMI,H. AHMADIAN,S. MOHAMMADI

期刊论文

A novel shape memory alloy actuated soft gripper imitated hand behavior

期刊论文

Size and shape effects of MnFeO nanoparticles as catalysts for reductive degradation of dye pollutants

期刊论文

一种将拓扑优化设计转化为增材制造结构的实现方法

刘书田, 李取浩, 刘君欢, 陈文炯, 张永存

期刊论文

300m 级特高拱坝建设关键技术与实践

王仁坤

期刊论文

Temperature effects of shape memory alloys (SMAs) in damage control design of steel portal frames

Xiaoqun LUO, Hanbin GE, Tsutomu USAMI

期刊论文

A fully solid-state cold thermal energy storage device for car seats using shape-memory alloys

期刊论文

板形计法的定义及实验应用

张进之,段春华,朱健勤

期刊论文

Calculation method on shape finding of self-anchored suspension bridge with spatial cables

Yan HAN, Zhengqing CHEN, Shidong LUO, Shankui YANG

期刊论文