基于Kriging代理模型的加筋柱壳结构优化

基于Kriging代理模型,研究了加筋柱壳型飞行器舱体结构形状和尺寸优化方法.对加筋柱壳结构建立了三维参数化模型,参数化设计变量包括纵向加强筋数量、尺寸和环向加强筋的位置、尺寸,利用试验设计法选取设计变量采样点,使用有限元静力分析和线性屈曲分析得到采样点的应力、变形、屈曲强度因子等响应值,依据设计变量和响应建立Kriging代理模型,使用优化算法对代理模型进行寻优,获得最优设计结果.整个优化过程在Workbench平台中实现,最优结构比初始模型重量减少了11.91％.加筋柱壳结构优化结果分析表明,所使用优化方法优化效果明显、工作流程清晰、优化效率高,具有较大的工程应用价值.     

电热水器的原理与检修

详细分析储水式电热水嚣的电路原理,以鲁斌牌QZD-1型热水器为饲介绍电热水器的电源电路,水位显示电路,防止干烧电路和防止漏电电路.重点介绍水位显示电路和防止干烧电路,水位显示电路主要以ICl(MC4069)反相器为核心,可以检测注水到莱一位置;防止干烧电路主要以IC2(LM339)比较器为棱心,实现当水箱水位低于2/6...     

基于单片机的水箱水位控制系统的设计

本设计旨在监测水箱水位,实现对水箱水位进行自动或者手动控制.系统以51单片机作为主控芯片,通过水泵为水箱上水和放水,通过按键对系统水位上、下限进行调整.     

基于有限元的绕线机主轴箱的结构改进及优化

为提高绕线机主轴箱的振动性能,采用基于有限元方法的COSMOS软件对绕线机的主轴箱进行了模态分析和结构的优化,仿真主轴箱前10阶固有频率和对应的振动模态.结果发现,基频共振频率仅有767 Hz,变形比例达1.31%;第2阶共振频率为801 Hz,变形比例为1.19%,对共振频率极大地限制了绕线机工作转速的提升.通过增设加强筋进行结构的改进,使主轴箱的基频提高了5.4%.第2阶共振频率提高了23.6%.采用结构优化方法使基频得到改善,并在增设加强筋的条件下,优化支撑板间距可使基频共振频率提高28.7%.     

太阳能热水器水位显示器的制作

随着太阳能技术的成熟、安装太阳能热水器的越来越多,水位显示器在太阳能热水器中能指示水箱的存水量。因水箱安装在楼顶上、用户无法观察水箱的水位,水位显示器安装在用户家中,探测器安装在水箱中通过电线相连,用户在家中就能观察到水箱中的水位,做到用热水有数,缺水时及时上水。水位显示器装在塑料盒中,一般安装在浴室墙上以便于观察。水位显示分三档,用三个指示灯分别显示桶容量的1/3,2/3和水满,水到三种水位时相应的指示灯     

基于MSP430的水温加热控制系统

加热控制系统是以MSP430单片机为核心,通过一定的人机交互实现水箱水位和温度的控制。利用定时器实现系统的定时加热;使用不同数目的加热棒实现功率的调节;使用温度传感器LM35H采集数据,经A/D转换后把数据传送给单片机,控制水箱的温度;利用浮球、磁电开关、电磁阀控制水箱水位。     

水箱水位控制器的设计与实现

介绍了水箱水位控制中一种新型的实用电路。它是采用数字电路与模拟电路相结合、集成电路与分立元件相结合的方法，通过红外光电传感器将水箱水位的高低信号转换成开关数字信号，然后在控制电路和驱动电路的作用下实现对水箱水位的自动控制和故障报警。该电路具有简单、经济、稳定可靠、容易实现的特点，适用于城镇居民楼房，特别是农村住宅楼房生活用水水箱的水位自动控制。     

液体晃动条件下飞艇水箱动力响应仿真分析

为了增加重载飞艇的载重能力,在满足结构强度要求下飞艇上的贮水水箱需要采用薄壁结构、轻质材料等方法来减轻重量。水箱在空中受到风载荷或其他载荷的作用,会导致水箱中的液体发生晃动,水箱在液体晃动和外部载荷共同作用下,可能会遭到破坏。考虑流固耦合作用对水箱结构的影响,分别从液体小幅晃动和大幅晃动两种情况对水箱动力响应进行研究。对于大幅晃动的情况,以试验所得风载荷加速度函数作为激励,利用计算流体动力学(CFD)方法进行仿真分析。分析结果表明,小幅晃动条件下,即使水箱发生共振,其结构也不会遭到破坏;大幅晃动条件下,1. 3 mm以下壁厚钢材料水箱和2.1 mm以下壁厚铝合金材料水箱结构会遭到破坏。该分析结果可为水箱部分设计参数的确定提供参考依据。     

一种新的简单的水位控制电路

这里向大家介绍最近实验的一种简单的水位控制器电路。它是利用现代电子技术进行水位自动控制,可以可靠地防止水箱溢水和无水现象的发生,适用于农村家庭和小城镇居民自制的自来水水箱水位的控制。下面介绍这种控制器的工作原理及制作方法。图1是水箱示意图,图2是控制电路原理图。     

通过模具CAE技术改善LED面板变形研究

本文以LED面板为例,阐述CAE软件在改善塑料产品变形中的应用.研究表明,采用CAE软件进行变形分析可以在试模之前找到翘曲变形的主要原因,如产品结构和壁厚、注射工艺参数设定、浇口位置和顺序等,将问题可视化,最终确定优化方案,减少试模次数和提高一次试模成功率.     

优化模型在挤出吹塑工艺模拟中的运用

为减轻汽车塑料燃油箱的总质量,模拟挤出吹塑工艺中燃油箱的壁厚变化。将模拟问题分为3部分,即型坯长度优化、静态柔性变形板优化和垂直厚度分布系统优化。每个优化过程抽象为一个数学模型,在MATLAB中求解数学模型并获得最优解。优化结果与实际试验结果基本一致,产品总质量偏差小于3%,壁厚偏差小于7%,证明模拟方法合理。     

A systematic topology optimization approach for optimal stiffener design

A systematic topology optimization based approach is proposed to design the optimal stiffener of three-dimensional shell/plate structures for static and eigenvalue problems. Optimal stiffener design involves the determination of the best location and orientation. In this paper, the stiffener location problem is solved by a microstructure-based design domain method and the orientation problem is modelled as an optimization orientation problem of equivalent orthotropic materials, which is solved by a newly developed energy-based method. Examples are presented to demonstrate the application of the proposed approach.     

粒子群算法在汽包锅炉水位控制系统中的应用研究

锅炉汽包水位控制系统是一种典型的过程控制系统,水位过高容易烧坏过热器,水位过低会造成水冷壁破裂,因此汽包水位的控制是锅炉控制的一个难点。由于锅炉水位控制系统的不确定性和非线性,传统的PID控制方法很难得到满意的控制效果,将利用粒子群算法对PID控制器参数进行优化,通过MATLAB工具,进行仿真研究,利用粒子群算法能够极大地缩短调节时间,减小超调量,增加结果准确度,对过程控制系统的参数优化提供一定的理论指导意义。     

A numerical approach to the analysis of circular cylindrical water tanks

This paper presents a novel numerical approach to the solution of differential equations governing the deformation of a circular cylindrical water tank whose axis is vertical. The approach is a combination of the Runge-Kutta numerical method of solution of ordinary differential equations and of numerical optimization methods. The results obtained using this approach are compared with the results from other methods. The usefulness of the method is discussed.     

Two-stage size-layout optimization of axially compressed stiffened panels

In this study, a two-stage optimization framework is proposed for cylindrical or flat stiffened panels under uniform or non-uniform axial compression, which are extensively used in the aerospace industry. In the first stage, traditional sizing optimization is performed. Based on the buckling or collapse-like deformed shape evaluated for the optimized design, the panel can be divided in sub-regions each of which shows characteristic deformations along axial and circumferential directions. Layout optimization is then performed using a stiffener spacing distribution function to represent the location of each stiffener. A layout coefficient is assigned to each sub-region and the overall layout of the panel is optimized. Three test problems are solved in order to demonstrate the validity of the proposed optimization framework: remarkably, the load-carrying capacity improves by 17.4 %, 66.2 % and 102.2 % with respect to the initial design.     

Predictive control and thermal energy storage for optimizing a multi-energy district boiler

As part of the OptiEnR research project, the present paper deals with optimizing the multi-energy district boiler of La Rochelle (France) adding to the plant a controlled thermal storage tank. This plant supplies domestic hot water and heats residential and public buildings, using renewable and fossil resources. Due to the complexity of the district boiler as a whole and the strong interactions between the sub-systems, previous works focused first on a modular approach used for the modeling of the plant. Next, a methodology based on both a multi-resolution analysis and the use of artificial neural networks was proposed to forecast the outdoor temperature and the thermal power consumption of the hot water distribution network. The present paper deals first with the modeling of a stratified thermal storage tank. Next, a basic and easy-to-implement controller was developed. Finally, using the global model of the district boiler, a model predictive controller generated optimal command sequences dealing with the flow of the water passing through the storage tank and the wood boiler set-point temperature. As a result, the consumption of fossil fuels, CO₂ emissions and functioning cost were significantly reduced. Energy is stored during low-demand periods and used when demand is high, instead of engaging the gas–fuel oil boiler.     

Optimization of load-transfer and load-diffusion

The problem of optimization of a stringer, or a stiffener, attached to an elastic infinite plate is investigated. The plate is exposed to tensioning by uniformly distributed forces, and also to contact stresses due to forces as a result of enforced continuity with the reinforcing stiffener. The novelty of the optimization problem is emphasized in an elongated, needle-shaped form of the stringer. The cross-section together with its axial stiffness is variable along the axis of the stiffener. The cross-section, which is primarily unknown, represents the searchable function in the optimization problems. A flattened, plate-shaped stiffener that supports a semi-infinite prismatic body is also briefly pursued. Optimization problems of the flattened stiffener are proved to be quite similar to those of the elongated one. The governing equations of both studied cases transform into each other by means of alternation of the elastic constants. Consequently, the optimal cross-sections of both problems turn out to be identical after the appropriate choice of material parameters. The article studies two optimization problems: minimization of the ultimate stress along the stringer and minimization of the stringer mass under the constraints on the integral compliance of the reinforced body. The shape optimization is studied in the case of an isolated stiffener and in the case of a periodic array of stiffeners. The analytical expressions for the optimal cross-section profiles are found.     

Design optimization of stiffened storage tank for spacecraft

Stiffened storage tank is an important structural component in spacecraft. Its structural weight is one of the key criterions in the design phase. This paper focuses on the design optimization of the structure by using finite element method, structural sensitivity analysis techniques, and sequential linear/quadratic programming aimed to reduce the structural weight. Design variables include the numbers of stiffeners, stiffeners’ section dimensions, and shell thickness distribution. Detailed finite element modeling processes are presented, which are the ways to construct the stiffener (beam orientation and offset) and shell elements and the ways to determine the analysis model and structural boundary conditions. A brief introduction to sensitivity analysis and optimization solution algorithm is also given. Main attention is paid to the studies of design optimization of the tank structure, including the selection of design cases, evaluation, and comparison of the optimal results. There are six design cases considered in the design procedures. Numerical results show that by using the above computational techniques, the structural weight is effectively reduced. In this work, MSC.Patran/Nastran is employed to construct the Finite Element Model (FEM), and JIFEX, which is developed in our group, is used to conduct the structural design optimization. JIFEX is a structural analysis and optimization software package developed by Gu and colleagues in the Dalian University of Technology Department of Engineering Mechanics. Among its many functions is the ability to analyze and optimize piezoelectric smart structures.     

Optimal topology design of internal stiffeners for machine pedestal structures using biological branching phenomena

Naturally evolved biological structures exhibit the optimal characteristics of light weight, high stiffness, and high strength. Based on the growth mechanism of biological branch systems in nature, an optimization method for internal stiffener plate distribution in box structures is suggested. Under the given load and support conditions, the internal stiffener plates of machine pedestal structures grow, bifurcate, and degenerate towards the direction of maximum overall structural stiffness in accordance with the adaptive growth law. The optimal and distinct distribution of internal stiffener plates with the most effective load path is thus obtained. Based on this, a size optimization for lightweight design is conducted, in which the self-weight of the structures is taken as the design objective, and the natural vibration frequency and static stiffness in the direction that is sensitive to machining accuracy are set as constraints. Finally, an optimized structure is obtained. The effectiveness of the proposed method is verified by using a precision grinder bed as an example. The results of numerical simulation and 3D–printed model experiment indicate that both the dynamic and the static performance of the optimized structure are improved, while the structural weight is reduced by compared with the initial structure. The suggested design method provides a new solution approach for the design optimization of machine pedestal structures.