共查询到20条相似文献,搜索用时 125 毫秒
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模型降阶方法通过构造全阶模型的低阶近似模型有效提升了求解效率,同时也保留了原阶模型的主要信息从而保证了较高的计算精度。对于结构非线性以及参数化的模型降阶问题,常需要重复计算刚度矩阵等非线性以及参数依赖项,求解效率较低。此外,当参数化模型的几何形状改变时,往往需要重复进行CAD与有限元(FEA)模型的转换,这对于复杂结构较为耗时。等几何分析采用描述几何形状的非均匀有理B样条(NURBS)插值物理场,实现了CAD与FEA模型的统一,消除了两者之间繁琐的模型转换过程,其具有几何精确、高阶连续等优点,并且几何形状在细化过程中保持不变,非常适合于薄壁类结构的分析以及参数化表达。该研究结合等几何分析、特征正交分解(POD)以及离散经验插值方法(DEIM)研究参数化的平面曲梁结构的非线性动力学模型降阶问题。数值结果表明,基于等几何分析的POD-DEIM降阶模型能够显著提升平面曲梁结构的非线性动力学计算效率,并且该模型对于参数化以及变载荷等情形显示出了良好的适应性。 相似文献
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提出基于Kriging模型的有限元模型修正方法。Kriging模型为据区域内若干信息样品某种特征数据对该区域同类特征未知数作线性无偏、最小方差估计方法,其只用少量样本即可获得较高精度预测结果。用Kriging模型对平面桁架进行有限元模型修正,验证该方法的可行性与准确性;对一连续梁拱桥进行模型修正,并与GA算法、BP神经网络方法模型修正结果比较分析。Kriging模型仅需一定量测量频率信息即可完成模型修正,能避免修正过程中进行有限元模型迭代计算。结果表明,该方法能准确预测有效频率范围(active frequency range)外模态信息,计算效率、精度较高,可用于工程实践。 相似文献
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该文建议采用Kriging代理模型数值求解拉压不同模量平面问题。通过本构方程光滑化、有限元法及拉丁超立方采样技术,对拉压不同模量桁架与二维平面问题,给出了基于Kriging模型的近似数值解,以代理基于有限元的数值解,并探讨了样本点数目和问题规模对所建Kriging近似模型求解精度/效率的影响。数值算例表明:所提方法可为求解拉压不同模量平面问题提供精度合理的近似数值解。当问题规模较大且正问题需要多次求解时,该方法有望显著减少计算时间,这对于降低拉压不同模量反问题与优化问题的计算开销十分重要。 相似文献
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提出了一种模型修正方法,可以在不依赖模型灵敏度的前提下,利用较少的计算量实现对结构有限元模型的参数修正。该方法首先构建代理模型替代结构有限元模型,通过计算少量样本点,训练支持向量回归机(support vector regression, SVR)预测参数所对应的响应;其次,以结构固有频率的残差为目标函数,利用粒子群优化算法实现全局寻优求解,得到修正后的有限元模型参数;进一步,以带孔平板为试验研究对象,基于实测数据验证了所提方法的有效性,并讨论不同参数、样本点数等对模型修正精度的影响;最后,用某卫星结构模型修正算例证明了该方法相对基于灵敏度分析的方法在计算耗时上的优势。该研究旨在为具有复杂参数-响应特征的结构模型修正提供技术支持。 相似文献
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运用模块化思想,完成了舰船结构模块和功能模块的划分,并通过对功能模块的变参,实现了自动生成船舶各个组成部件几何模型的建模系统。最后,以某舰几何模型为基础对该舰磁场分布进行有限元分析计算。结果表明,该方法计算精度较高,能够较好反映舰船空间磁场的分布。 相似文献
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针对传统贝叶斯算法在高维参数下采样效率低且收敛难的问题,建立了基于多链差分进化算法的贝叶斯有限元模型修正方法。在标准马尔可夫链蒙特卡罗(MCMC)方法的基础上,引入差分进化算法,通过多条马氏链间的随机差分运算来自适应选择条件分布的大小和方向以快速逼近目标分布;引入子空间采样算法,通过自适应选择优良的参数维度进行采样以提高采样效率;引入异常链检测算法,通过在采样的非平稳期对马氏链进行异常检测与剔除以提高在平稳期的采样效率。简支梁理论模型和实验室4层框架结构的模型修正结果表明:该方法修正精度较高,且具有良好的抗噪性,在高阶频率以及振型下的修正效果均优于DRAM算法,为解决不确定性模型修正中的计算精度提供了一种新手段。 相似文献
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研究了典型多核集群任务分配中的节点内通讯特性。基于0-1整数非线性规划模型和线性松弛技术,给出了一种0-1整数线性规划任务分配问题求解优化模型。由于节点内的通讯量与通讯延迟较大,以最小化计算代价和节点间通讯代价为研究目标的传统求解模型具有严重的局限性,而该求解模型考虑了节点内通讯代价,并采用了线性规划松弛技术,其目标是最小化计算代价、节点间通讯代价和节点内通讯代价。计算结果验证了提出的模型的有效性。 相似文献
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Task composition in cloud manufacturing involves the selection of appropriate services from the cloud manufacturing platform and combining them to process the task with the purpose of achieving its expected performance. Calculation methods for achieving the performance expected by customers when the task has two or more composition patterns (e.g. sequential and switching pattern) are necessary because most tasks have multiple composition patterns in cloud manufacturing. Previous studies, however, have focused only on a single composition pattern. In this paper, we regard a task as a directed acyclic graph, and propose graph-based algorithms to obtain cost, execution time, quality and reliability of a task having multiple composition patterns. In addition, we model the task composition problem by introducing cost and execution time as performance attributes, and quality and reliability as basic attributes in the Kano model. Finally, an experiment to compare the performances of three metaheuristic algorithms (namely, variable neighbourhood search, genetic, and simulated annealing) is conducted to solve the problem. The experimental result shows that the variable neighbourhood search algorithm yields better and more stable solutions than the genetic algorithm and simulated annealing algorithms. 相似文献
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Cost analysis is crucial in the design of assembly systems and the decision on their level of automation (LoA). This paper presents a cost estimation model of assembly system that is used to decide their LoA during the early phase of projects. Based on an extensive literature review, a complete cost model integrating multiple cost drivers is proposed. This model is then exploited to create the objective function of an integer linear programme model utilised to solve the LoA decision problem. The work provides a way to perform cost estimation of assembly systems alternatives and to decide the most appropriate LoA in assembly. The cost estimation model is built with a parametric approach allowing the definition of various optimisation objectives. The proposed integer programme, complement this approach by proposing the suitable constraints set, that describes the LoA decision problem. 相似文献
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Effective conduct with End of Life (EOL) products is a hot research topic in green and smart manufacturing. For EOL product recycling and remanufacturing, a fundamental problem is to design an efficient disassembly line under consideration of stochastic task processing times. This problem focuses on selecting alternative task processes, determining the number of opened workstations, and assigning operational tasks to the workstations. The goal is to minimise the total cost consisting of workstation operational cost and hazardous component processing cost. Most existing works assume that the probability distribution of task processing times can be estimated, however, it is often not likely to access the complete probability distribution due to various difficulties. Therefore, this study investigates disassembly line design with the assumption that only the mean, standard deviation and an upper bound of task processing times are known. Our main contributions include: (i) a new decomposition color graph is proposed to intuitively describe all possible processes, (ii) a new distribution-free model is proposed, and (iii) some problem properties are established to solve the model. Experimental results show that the distribution-free model can effectively deal with stochastic task processing times without given probability distributions. 相似文献
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产品开发过程中单输入多输出耦合设计任务间存在复杂的信息依赖关系。采用单阶段方法的任务执行方式时,因所执行的任务数量多并且需传递的信息量大,致使任务间存在的复杂信息关系难以被理清,从而导致任务执行过程中的方案分配不够合理,任务间的迭代返工次数过多,产品开发周期过长。针对这些问题,在深入分析单输入多输出耦合设计任务单阶段迭代模型的基础上,提出了一种任务迭代过程中的信息处理策略,并构建了一种单输入多输出耦合设计任务的二阶段迭代模型及其求解执行时间的数学模型。应用该数学模型,可以计算得到最佳二阶段设计任务分配方案。以某发动机开发项目为例,进行了该方法的应用分析。研究表明,采取二阶段迭代模型,任务迭代执行时间比单阶段短,并且通过合理分配在1,2两个阶段执行的任务,能够获得最短的二阶段任务迭代执行时间。该方法根据任务间不同的信息关系选择合适的任务迭代模型,能够有效缩短产品开发周期,可为产品设计人员在产品开发过程中选择合理的任务执行方式提供一定的理论参考。 相似文献
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一种新颖的用于触觉再现的平行菱形链连接模型 总被引:1,自引:1,他引:0
针对如何提高虚拟触觉再现的精度与实时性问题,提出了一种新颖的基于物理意义的平行菱形链连接触觉变形模型.该模型中各个链结构单元中菱形的长度等比例变化,因而计算量小;改变链结构单元中菱形的长度和夹角就可方便对不同的柔性体进行建模,系统中各个链结构单元的相对位移的叠加对外等效为物体表面的变形,与之相连的弹簧弹性力的合力等效为物体表面的接触力.利用手控器对柔性体的接触变形和实时虚拟触觉反馈进行了仿真.实验表明所提出的方法适用于柔性体的触觉反馈计算,能够满足精细作业对虚拟现实系统的要求. 相似文献
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This paper is devoted to the analysis and computation of overall as well as various subsystem availabilities of a urea fertilizer plant. Based on the analysis, appropriate maintenance strategies for different situations have been developed. Using Lagrange's multiplier technique the cost of maintenance and manpower is analysed. By minimizing the maintenance cost allocation to various subsystems, the optimum repair policy is determined. 相似文献