Web Layout Design of Large Cavity Structures Based on Topology Optimization

Large cavity structures are widely employed in aerospace engineering, such as thin-walled cylinders, blades andwings. Enhancing performance of aerial vehicles while reducing manufacturing costs and fuel consumptionhas become a focal point for contemporary researchers. Therefore, this paper aims to investigate the topologyoptimization of large cavity structures as a means to enhance their performance, safety, and efficiency. By usingthe variable density method, lightweight design is achieved without compromising structural strength. Theoptimization model considers both concentrated and distributed loads, and utilizes techniques like sensitivityfiltering and projection to obtain a robust optimized configuration. The mechanical properties are checked bycomparing the stress distribution and displacement of the unoptimized and optimized structures under the sameload. The results confirm that the optimized structures exhibit improved mechanical properties, thus offering keyinsights for engineering lightweight, high-strength large cavity structures.

A strategy for lightweight designing of a railway vehicle car body including composite material and dynamic structural optimization

Rolling stock manufacturers are finding structural solutions to reduce power required by the vehicles,and the lightweight design of the car body represents a possible solution.Optimization processes and innovative materials can be combined in order to achieve this goal.In this framework,we propose the redesign and optimization process of the car body roof for a light rail vehicle,introducing a sandwich structure.Bonded joint was used as a fastening system.The project was carried out on a single car of a modern tram platform.This preliminary numerical work was developed in two main steps:redesign of the car body structure and optimization of the innovated system.Objective of the process was the mass reduction of the whole metallic structure,while the constraint condition was imposed on the first frequency of vibration of the system.The effect of introducing a sandwich panel within the roof assembly was evaluated,focusing on the mechanical and dynamic performances of the whole car body.A mass saving of 63%on the optimized components was achieved,corresponding to a 7.6%if compared to the complete car body shell.In addition,a positive increasing of 17.7%on the first frequency of vibration was observed.Encouraging results have been achieved in terms of weight reduction and mechanical behaviour of the innovated car body.

Multi-Scale Design and Optimization of Composite Material Structure for Heavy-Duty Truck Protection Device

In this paper,to present a lightweight-developed front underrun protection device(FUPD)for heavy-duty trucks,plain weave carbon fiber reinforced plastic(CFRP)is used instead of the original high-strength steel.First,the mechanical and structural properties of plain carbon fiber composite anti-collision beams are comparatively analyzed from a multi-scale perspective.For studying the design capability of carbon fiber composite materials,we investigate the effects of TC-33 carbon fiber diameter(D),fiber yarn width(W)and height(H),and fiber yarn density(N)on the front underrun protective beam of carbon fiber compositematerials.Based on the investigation,a material-structure matching strategy suitable for the front underrun protective beam of heavy-duty trucks is proposed.Next,the composite material structure is optimized by applying size optimization and stack sequence optimization methods to obtain the higher performance carbon fiber composite front underrun protection beam of commercial vehicles.The results show that the fiber yarn height(H)has the greatest influence on the protective beam,and theH1matching scheme for the front underrun protective beamwith a carbon fiber composite structure exhibits superior performance.The proposed method achieves a weight reduction of 55.21% while still meeting regulatory requirements,which demonstrates its remarkable weight reduction effect.

Lightweight Design and Verification of Gantry Machining Center Crossbeam Based on Structural Bionics

The lightweight and high efficiency of natural structures are the inexhaustible sources for engineering improvements. The goal of the study is to find innovative solutions for mechanical lightweight design through the application of structural bionic approaches. Giant waterlily leaf ribs and cactus stem are investigated for their optimal framework and superior performance. Their structural characteristics are extracted and used in the bio-inspired design of Lin MC6000 gantry machining center crossbeam. By mimicking analogous network structure, the bionic model is established, which has better load-carrying capacity than conventional distribution. Finite Element Method （FEM） is used for numerical simulation. Results show better specific stiffness of the bionic model, which is increased by 17.36%. Finally the scaled models are fabricated by precision casting for static and dynamic tests. The physical experiments are compared to numerical simulation. The results show that the maximum static deformation of the bionic model is reduced by about 16.22%, with 3.31% weight reduction. In addition, the first four natural frequencies are improved obviously. The structural bionic design is a valuable reference for updating conventional mechanical structures with better performance and less material consumption.

The Lightweight Design of Low RCS Pylon Based on Structural Bionics

A concept of Specific Structure Efficiency (SSE) was proposed that can be used in the lightweight effect evaluation ofstructures.The main procedures of bionic structure design were introduced systematically.The parameter relationship betweenhollow stem of plant and the minimum weight was deduced in detail.In order to improve SSE of pylons, the structural characteristicsof hollow stem were investigated and extracted.Bionic pylon was designed based on analogous biological structuralcharacteristics.Using finite element method based simulation, the displacements and stresses in the bionic pylon were comparedwith those of the conventional pylon.Results show that the SSE of bionic pylon is improved obviously.Static, dynamic andelectromagnetism tests were carried out on conventional and bionic pylons.The weight, stress, displacement and Radar CrossSection (RCS) of both pylons were measured.Experimental results illustrate that the SSE of bionic pylon is markedly improvedthat specific strength efficiency and specific stiffness efficiency of bionic pylon are increased by 52.9% and 43.6% respectively.The RCS of bionic pylon is reduced significantly.

Carbody Structural Lightweighting Based on Implicit Parameterized Model

Most of recent research on carbody lightweighting has focused on substitute material and new processing technologies rather than structures. However, new materials and processing techniques inevitably lead to higher costs. Also, material substitution and processing lightweighting have to be realized through body structural profiles and locations. In the huge conventional workload of lightweight optimization, model modifications involve heavy manual work, and it always leads to a large number of iteration calculations. As a new technique in carbody lightweighting, the implicit parameterization is used to optimize the carbody structure to improve the materials utilization rate in this paper. The implicit parameterized structural modeling enables the use of automatic modification and rapid multidisciplinary design optimization （MDO） in carbody structure, which is impossible in the traditional structure finite element method （FEM） without parameterization. The structural SFE parameterized model is built in accordance with the car structural FE model in concept development stage, and it is validated by some structural performance data. The validated SFE structural parameterized model can be used to generate rapidly and automatically FE model and evaluate different design variables group in the integrated MDO loop. The lightweighting result of body-in-white （BIW） after the optimization rounds reveals that the implicit parameterized model makes automatic MDO feasible and can significantly improve the computational efficiency of carbody structural lightweighting. This paper proposes the integrated method of implicit parameterized model and MDO, which has the obvious practical advantage and industrial significance in the carbody structural lightweighting design.

Effect of Lightweight Aggregate Pre-wetting on Microstructure and Permeability of Mixed Aggregate Concrete

The influence of lightweight aggregate （LWA） pre-wetting on the chemical bound water and pore structure of the paste around aggregate as well as concrete permeability were investi-gated. The results show that, in early age the dry LWA has significant effect on the formation of dense paste around it and improving the concrete impermeability. However the prewetted LWA has strong water-releasing effect in later age, which increases the hydration degree of the paste around it, and makes the adjacent paste develop a structure with low porosity and finer aperture, furthermore the concrete impermeability can be improved. It is suggested that, as for concrete with low durability requirement, the LWA without pre-wetting treatment can be used as long as meet the workability re-quirement of fresh concrete, the good impermeability of concrete can be gained as well. As for con-crete with high durability requirement, the prewetted LWA should be used, and the pre-wetting time should be extended as long as possible, in order to optimize the concrete structure in long term, and improve the concrete durability.

Improving the design of reinforcing frames by simulating the arch and peltate venation structures

Based on the analyses on arch and peltate venation structures, the design of reinforcing frames was improved. First, distribution rules of the arch structure were summarized. According to the load condition and the structure of the frame, a mechanical model of arch structure was devel- oped, and two solutions for the model were analyzed and compared with each other. Through the a- nalysis, application rules of arch structure for improving the design were obtained. Then, distribu- tion rules of peltate venation structure were summarized. By using the same method, application rules of peltate venation structure for improving the design were also obtained. Finally, mechanical problem of the frame was described, and rib arrangement of the frame was redesigned. A parameter optimization for the widths of ribs in bionic arrangement was also carried out to accomplish the im- proving design. Comparison between bionic and conventional reinforcing frames shows that the weight is reduced by as much as 15.3%.

Design and Optimization of Steel Car Body Structures via Local Laser-Strengthening

Continuously rising demands of legislators require a significant reduction of CO2-emission and thus fuel consumption across all vehicle classes. In this context, lightweight construction materials and designs become a single most important factor. The main engineering challenge is to precisely adapt the material and component properties to the specific load situation. However, metallic car body structures using “Tailored blanks” or “Patchwork structures” meet these requirements only insufficiently, especially for complex load situations (like crash). An innovative approach has been developed to use laser beams to locally strengthen steel crash structures used in vehicle bodies. The method tailors the workpiece hardness and thus strength at selected locations to adjust the material properties for the expected load distribution. As a result, free designable 3D-strengthening-patterns surrounded by softer base metal zones can be realized by high power laser beams at high processing speed. The paper gives an overview of the realizable process window for different laser treatment modes using current high brilliant laser types. Furthermore, an efficient calculation model for determining the laser track properties (depth/width and flow curve) is shown. Based on that information, simultaneous FE modelling can be efficiently performed. Chassis components are both statically and cyclically loaded. Especially for these components, a modulation of the fatigue behavior by laser-treated structures has been investigated. Simulation and experimental results of optimized crash and deep drawing components with up to 55% improved level of performance are also illustrated.

Configuration Synthesis and Lightweight Networking of Deployable Mechanism Based on a Novel Pyramid Module

Deployable mechanism with preferable deployable performance,strong expansibility,and lightweight has attracted much attention because of their potential in aerospace.A basic deployable pyramid unit with good deployability and expandability is proposed to construct a sizeable deployable mechanism.Firstly,the basic unit folding principle and expansion method is proposed.The configuration synthesis method of adding constraint chains of spatial closed-loop mechanism is used to synthesize the basic unit.Then,the degree of freedom of the basic unit is analyzed using the screw theory and the link dismantling method.Next,the three-dimensional models of the pyramid unit,expansion unit,and array unit are established,and the folding motion simulation analysis is carried out.Based on the number of components,weight reduction rate,and deployable rate,the performance characteristics of the three types of mechanisms are described in detail.Finally,prototypes of the pyramid unit,combination unit,and expansion unit are developed to verify further the correctness of the configuration synthesis based on the pyramid.The proposed deployable mechanism provides aference for the design and application of antennas with a large aperture,high deployable rate,and lightweight.It has a good application prospect in the aerospace field.

CFRP在汽车轻量化与安全中的应用进展

碳纤维复合材料(Carbon Fiber Reinforced Polymer,CFRP)具有比强度高、吸能性好等优点,在汽车结构安全及轻量化中的应用优势明显,前景广阔。本文综述了CFRP在汽车轻量化及安全性中应用的研究进展,从汽车车身、底盘以及配件等方面阐述了CFRP在汽车轻量化的应用,从安全性的角度分析了CFRP在汽车安全部件的优势,指出了制约CFRP应用的结构设计理论及异质连接工艺等难点,并展望了未来CFRP在汽车领域的应用前景。旨在拓展CFRP在汽车轻量化与安全中的应用范围,为其在汽车工业发展及轻量化中的广泛应用提供参考。

结合CWT和LightweightNet的滚动轴承实时故障诊断方法

针对普通的深度学习算法用于轴承故诊断分类时计算量大、消耗成本高的问题,提出一种结合连续小波变换和轻量级神经网络的滚动轴承实时故障诊断方法。首先,使用Morlet母小波函数对轴承振动加速度数据进行连续小波变换,提取出时频域特征并将一维信号转换成二维图片;然后,结合分组卷积、通道混洗、倒残差结构等轻量级神经网络设计元素设计一个轻量级卷积神经网络LightweightNet用于时频图片的故障分类,LightweightNet网络在保证具有足够特征提取能力的同时还具有轻量级特点。使用凯斯西储大学轴承故障数据集进行实验表明,本方法相比于其他使用经典轻量级神经网络的方法具有更少的参数、最高的准确率和更快的诊断速度,基本可以实现滚动轴承的实时故障诊断,且在内存消耗与模型存储占用空间方面远小于其他同类方法。

Lightweight Technologies in Sustainable Architecture:The Importance of Connections in Disassembly

The aim of this paper is to investigate the role of lightweight structures and connections in the DfD(design for disassembly)framework.The construction sector is facing pressure to reduce its environmental impact,which has led to heightened interest in DfD as a strategy for transitioning from a linear“Cradle to Grave”economic model to a circular“Cradle to Cradle”model.At the social level,DfD’s technological and spatial flexibility provides opportunities for self-build and self-maintenance processes,which can decrease land consumption and reduce costs for both owners and tenants.In this context,lightweight structures and connections are crucial for enabling these processes.The methodology used for analysis involves breaking down three technological elements chosen from three different projects to evaluate ease of disassembly,flexibility,potential for reuse,and recyclability.As a result,this paper aims to promote the development of an abacus of existing technological solutions,to provide designers with a tool that can help them pursue DfD strategies.

探测器机械结构静力学分析与轻量化设计

在产品设计过程中,机械结构的静力学分析与轻量化设计对产品的整体质量有着极为重要的影响。对产品的机械结构进行静力学分析可以保证产品有较好稳定性,对产品进行轻量化设计则是提高产品的综合性能,比如在不影响强度的情况下减小产品质量,从而提高产品综合品质。基于此,本文将结合3He管探测器的设计,对其主要部件进行静力学分析,并借助静力学分析结果对探测器的密闭腔体与盖板进行轻量化设计。

装配式轻钢框架-轻钢骨架轻混凝土墙板结构抗震性能

为研究装配式轻钢框架-轻钢骨架轻混凝土墙板结构抗震性能,对1个足尺轻钢框架结构试件和3个足尺轻钢框架-轻钢骨架轻混凝土墙板结构试件进行了低周反复荷载下的抗震性能试验及理论分析,试件变量包括:2种装配构造,即内嵌式装配墙板、外贴式装配墙板;2种轻钢骨架轻混凝土墙板,即框架式轻钢骨架轻混凝土墙板、桁架式轻钢骨架轻混凝土墙板。研究了各试件的破坏特征和损伤演化过程,分析了结构滞回特性、承载力、变形能力、刚度退化、耗能性能和应变。结果表明:装配式轻钢框架-轻钢骨架轻混凝土墙板结构共同工作性能良好,其水平承载力相比轻钢框架提高了204.7%~210.4%,抗侧刚度提高了257.3%~512.5%,结构变形及耗能能力有显著提高;内嵌墙板的自攻钉连接构造以及外贴墙板的螺栓连接构造传力性能可靠,结构具备2道抗震防线的受力特征;基于简化塑性分析模型以及拉压杆软化桁架模型,对试件承载力进行了计算,计算结果与试验符合较好。

应力驱动的2.5D梯度各向异性维诺多孔零件轻量化建模方法

为了提高多孔零件的设计自由度、内部力学性能梯度与实际应力分布的匹配度,提出一种应力驱动的2.5D梯度各向异性维诺多孔零件轻量化设计方法。将零件有限元分析结果分解为应力标量场和应力方向场,通过加权随机采样算法将应力标量场映射为零件设计域内的维诺站点分布,实现零件内部力学性能的梯度分布;将应力方向场映射为二维黎曼流形,提出一种基于胞元择优方向生长策略的各向异性维诺图生成算法,生成胞元沿黎曼流形分布的各向异性维诺图。在此基础上,通过偏置算法、调和距离场和拉伸算法生成光滑的梯度各向异性维诺多孔零件。最后,采用有限元分析、三点弯曲实验等方法将所设计的多孔零件和其他多孔零件进行比较分析。实验结果表明,所提出的梯度各向异性维诺多孔零件建模方法能有效提升零件内部力学性能梯度与实际应力分布的匹配度,降低材料消耗,实现轻量化设计。

武器装备轻量化结构正向设计方法及应用

为满足武器装备轻量化的迫切需求,提升装备结构优化设计水平,提出了一种代理模型辅助多目标优化的结构正向设计方法。按照从概念设计到参数优化设计的流程,通过优化信息交互和代理模型重构来实现结构多目标优化设计。以轻型车载高炮弹箱架优化设计为例,首先,根据拓扑优化获得的最佳传力路径,建立几何模型和有限元分析模型。其次,通过灵敏度分析缩减设计变量,建立以一阶模态频率和结构强度为约束、最小化质量和最大化刚度为目标的优化模型。然后,使用差分进化算法求解基于Kriging模型的多目标优化问题;在优化过程中,通过比较中间优化结果调整优化模型,并采用基于期望改进的填充样本策略重构代理模型。最后,兼顾结构轻量化和安全,筛选44组优化解中的3组优势方案与初始设计进行比较,结果显示:在满足弹箱架结构性能的前提下,重量分别可减轻31.2%、24.7%和21.8%;所提结构正向设计方法能够明显提升轻量化效果,也可为相关结构优化设计提供参考。

轻量化高速列车制动盘材料-结构研究进展

400 km/h高速列车紧急制动的强热负荷,导致制动盘温升高、温度分布梯度大和热衰减强,已超出钢质制动盘能载极限,开发耐高温强耐磨的制动盘材料,同时提升制动盘通风散热能力成为制动技术发展瓶颈。综述高速制动盘材料从高强度铸钢和锻钢、轻量化铝基复合材料至耐高温耐磨碳陶复合材料和表面改性技术发展历程,随着碳陶复合材料的台架试验和表面改性技术的摩擦磨损试验研究的深化,表面改性轻质复合材料是制动盘材料未来发展方向。概述通风制动盘内部散热层散热筋结构形貌优化、摩擦层表面耐磨性能改善的发展现状,内部散热筋由直通道设计逐渐演化为弯曲、支柱以及分形通道,镂空结构能更好地加速空气流动提高散热;表面摩擦层引入打孔或划线,更易于摩擦粉尘的抛离从而稳定摩擦因数,保持制动效果;但复杂通风导流结构和打孔划线增加了制备工艺的难度,提出高速制动盘结构构型设计需要综合材料热力学性能、制备工艺及耐热耐磨需求,形成材料-结构-功能—体化设计理念,为实现更高速的制动盘优化设计提供参考。

轻钢装配式建筑性能优化设计综述

轻钢装配式结构施工周期短、抗震节能、可回收利用率高,但也存在热惰性差、重复热桥多、隔振性能差等缺陷。以CNKI数据库筛选出的有关轻钢装配式建筑的383篇文献和Web of Science核心合集的731篇文献为数据来源,利用CiteSpace对发文情况、研究热点及发展趋势进行可视化分析,为以后的相关研究提供参考。综述包括轻钢龙骨、轻钢轻质混凝土、轻钢框架等在内的典型装配式轻钢结构性能优化设计的研究现状。首先,从整体抗震性能、自攻螺钉连接、龙骨截面及腹板开孔、保温材料及构造角度分析了组合墙体力学性能优化设计的特点、效果和改进思路。之后,从增设保温材料、热桥阻断设计、相变储能应用和接缝密封处理4个方面提出优化墙体热工性能的方法和效果。最后,阐述了围护结构隔绝空气声、结构振动噪声及振动舒适度的优化设计方法,总结了多目标并行优化的研究现状和未来发展方向。

太阳电池阵弧形基板结构振动分析及优化设计

针对弧面型太阳电池阵新型基板结构,在满足结构安全的前提下以多参数轻量化设计为目标。本文基于等效板理论获得弧形太阳电池阵基板的各向异性等效性能参数,建立新构型太阳电池阵基板的三维有限元数值模型,并通过正弦扫频振动试验验证了模型的可靠性,进而初步实现了结构薄弱区域定位。最后结合工程实际,基于参数化建模结合多目标迭代优化的方法,分析结构在典型随机振动载荷作用下的最大应力随各特征参数的变化规律,从而获得满足结构安全条件下的补强优化方案,相比于原始结构,可使面板最大应力下降21%,若加强结构为单向无纬布,结构最大应力可进一步下降15.6%,为新构型太阳电池阵基板的轻量化设计提供支撑。