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考虑表面层厚度不确定的稳健性拓扑优化方法 被引量:5
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作者 李冉 刘书田 《力学学报》 EI CAS CSCD 北大核心 2021年第5期1471-1479,I0004,共10页
采用增材制造工艺制备结构件时,较差的成型精度和表面粗糙度会导致结构表面层异质,引起表面层厚度的不确定性.为了研究不确定性对拓扑优化结构性能的影响,进而获得对不确定性具有更低敏感性的结构构型,提出了考虑结构表面层厚度不确定... 采用增材制造工艺制备结构件时,较差的成型精度和表面粗糙度会导致结构表面层异质,引起表面层厚度的不确定性.为了研究不确定性对拓扑优化结构性能的影响,进而获得对不确定性具有更低敏感性的结构构型,提出了考虑结构表面层厚度不确定性的稳健性拓扑优化方法.首先,采用一种基于腐蚀操作的表面层识别技术,通过基于Helmholtz偏微分方程的PDE光滑过滤和基于Heaviside过滤、tanh函数的离散映射两个过程实现表面层异质等效模型的建立.其次,将表面层厚度作为服从高斯分布的随机变量,基于摄动有限元方法开展了不确定性传播的分析和系统随机响应的预测;以结构柔顺性均值和标准差的加权和作为优化目标,建立了考虑表面层厚度不确定性的拓扑优化模型,并推导了目标函数关于设计变量的敏度.最后,通过数值算例验证了该方法的有效性.数值结果表明,在设计过程中考虑表面层厚度不确定性对结构性能的影响,可以得到具有更强抵抗不确定性能力的结构构型,有效提升了结构性能的稳健性. 展开更多
关键词 稳健性设计 表面层异质 表面层识别 几何不确定性 摄动有限元 拓扑优化
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Digital Image Processing Methods for Bridge Coating Management and Their Limitations 被引量:1
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作者 Sangwook Lee 《Journal of Civil Engineering and Architecture》 2011年第1期39-47,共9页
Accurate and objective rust defect assessment is required to maintain good quality steel bridge coating surfaces and make a decision whether a bridge shall completely or partially be repainted. For more objective rust... Accurate and objective rust defect assessment is required to maintain good quality steel bridge coating surfaces and make a decision whether a bridge shall completely or partially be repainted. For more objective rust defect recognition, digital image recognition methods have been developed for the past few years and they are expected to replace or complement conventional painting inspection methods. Efficient image processing methods are also essential for the successful implementation of steel bridge coating warranty contracting where the owner, usually a state agency, and the contractor inspect steel bridge coating conditions regularly and decide whether additional maintenance actions are needed based on the processed data. There are two approaches to develop automated rust defect recognition methods: applying a statistical method or an artificial intelligence technique. This paper presents the application of previously developed image processing methods for defect evaluations on a bridge coating surface and discusses their limitations under three environmental conditions which are often encountered while acquiring digital images. 展开更多
关键词 BRIDGES DETERIORATION image processing condition assessment.
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