基于相似模型试验的导管架平台有限元模型修正
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摘要
根据设计尺寸建立的有限元模型与实际结构之间不可避免地存在一定偏差,须根据试验测量数据对有限元模型进行必要的修正。基于相似原理设计制作完整平台和损伤平台的缩尺模型,开展模态试验;根据模态置信准则(MAC)评价试验模态数据和有限元计算数据的相关性。应用灵敏度分析方法对结构设计变量进行分级,以有效识别出平台结构中的待修正参数。针对含有未知损伤的海洋平台,采用结构参数的优化方法,识别损伤位置并实现损伤平台有限元模型的更新。结果表明:对于完整平台,修正后前六阶固有频率的误差均值由修正前的17.22%降至2.78%,修正后的有限元模型更接近试验结构;平台损伤后MAC显著降低,根据优化方法可准确定位出2个缺失构件的位置,且修正后固有频率的误差均值由25.94%降至4.79%。通过修正可为在役海洋平台安全评估提供一个准确的有限元模型。
Since differences between the prototype structure and the corresponding numerical model are inevitable, it is necessary to update the finite element model(FEM) according to the experimental data. Based on the similarity theory, scaled models of intact jacket platform and damaged jacket platform were designed and the modal experiments were carried out. According to the modal confidence assurance criterion(MAC), the correlation between the modal data obtained by the experimental and finite element analysis(FEA) was assessed. The sensitivity analysis was used to classify the structural design variables so as to effectively identify the key parameters to be modified. For the platform with unknown damages, the optimization method on structural parameters was adopted for damage location identification and the FEM updating. The objective function of this method is based on the measured and analytical modal data. The analysis results show that for the intact platform, after FEM updating the average error of the first six natural frequencies between experiments and FEA reduced from 17.22% to 2.78%, which shows that the updated FEM is much closer to the experimental model. For the damaged platform, the MAC decreases significantly; the two damaged members of the platform are accurately located according to the optimization method; and after updating the average error of the frequencies decreases from 25.94% to 4.79%. This project provides a more accurate FEM model for the safety assessment of in-service offshore platforms.
Since differences between the prototype structure and the corresponding numerical model are inevitable, it is necessary to update the finite element model(FEM) according to the experimental data. Based on the similarity theory, scaled models of intact jacket platform and damaged jacket platform were designed and the modal experiments were carried out. According to the modal confidence assurance criterion(MAC), the correlation between the modal data obtained by the experimental and finite element analysis(FEA) was assessed. The sensitivity analysis was used to classify the structural design variables so as to effectively identify the key parameters to be modified. For the platform with unknown damages, the optimization method on structural parameters was adopted for damage location identification and the FEM updating. The objective function of this method is based on the measured and analytical modal data. The analysis results show that for the intact platform, after FEM updating the average error of the first six natural frequencies between experiments and FEA reduced from 17.22% to 2.78%, which shows that the updated FEM is much closer to the experimental model. For the damaged platform, the MAC decreases significantly; the two damaged members of the platform are accurately located according to the optimization method; and after updating the average error of the frequencies decreases from 25.94% to 4.79%. This project provides a more accurate FEM model for the safety assessment of in-service offshore platforms.
引文
[1] 林红,陈国明,朱本瑞,等.导管架海洋平台失效路径分析及连续倒塌机制[J].中国石油大学学报(自然科学版),2016,40(1):121-127.LIN Hong,CHEN Guoming,ZHU Benrui,et al.Failure paths identification and progressive collapse mechanism analysis of offshore jacket platform[J].Journal of China University of Petroleum (Edition of Natural Science),2016,40(1):121-127.
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[13] 李英超.基于模态参数识别的海洋平台结构模型修正技术研究[D].青岛:中国海洋大学,2012.LI Yingchao.Model updating of offshore platform structures based on model parameter identification [D].Qingdao:Ocean University of china,2012.
[14] WANG S H,LI Y,LI H.Structural model updating of an offshore platform using the cross model cross mode method:an experimental study [J].Ocean Engineering,2015(97):57-64.
[15] 刘超.导管架平台动力特性实验研究[D].天津:天津建筑大学,2014.LI Chao.The dynamic characteristics of jacket platform experimental research [D].Tianjin:Tianjin Architectural University,2014.
[16] GAO X,LING X Z,TANG L,et al.Soil-pile-bridge structure interaction in liquefying ground using shake table testing [J].Soil Dynamics & Earthquake Engineering,2011,31(7):1009-1017.
[17] 王济,胡晓.MATLAB在振动信号处理中的应用[M].北京:中国水利水电出版社,2006.
[18] 杨佑发,程亚鹏,李华新.环境激励下基于经验模式分解的结构模态参数识别方法[J].土木工程学报,2013,46(增2):73-78.YANG Youfa,CHENG Yapeng,LI Huaxin.Empirical mode decomposition based method of structural modal parameter identification under ambient excitation [J].China Civil Engineering Journal,2013,46(sup2):73-78.
[19] 吕涛,徐长航,陈国明,等.基于振动响应的导管架平台极限承载能力分析[J].中国石油大学学报(自然科学版),2016,40(3):155-162.Lü Tao,XU Changhang,CHEN Guoming,et al.Ultimate bearing capacity analysis of jacket platforms based on vibration response[J].Journal of China University of Petroleum (Edition of Natural Science),2016,40(3):155-162.
[20] ALLEMANG R J,PHILLIPS A W.Un-weighted and weighted versions of the modal assurance criterion (MAC) for evaluation of modal vector contamination [M].Berlin:Springer International Publishing,2014.
[21] 袁爱民,戴航,孙大松.考虑边界条件约束和参数灵敏度的斜拉桥有限元模型修正[J].应用基础与工程科学学报,2010,18(6):900-909.YUAN Aimin,DAI Hang,SUN Dasong.Finite element model updating for a cable-stayed bridge considering the boundary condition constraint and parameter sensitivity[J].Journal of Basic Science and Engineering,2010,18(6):900-909.
[22] LIU C S.Trial equation method based on symmetry and applications to nonlinear equations arising in mathematical physics [J].Foundations of Physics,2011,41(5):793-804.
[2] 朱本瑞,陈国明,林红,等.极端环境下导管架平台连续倒塌鲁棒性评估[J].中国石油大学学报(自然科学版),2015,39(6):138-144.ZHU Benrui,CHEN Guoming,LIN Hong,et al.Robustness assessment of jacket platforms for progressive collapse under extreme environmental loading[J].Journal of China University of Petroleum (Edition of Natural Science),2015,39(6):138-144.
[3] FRISWELL M I,MOTTERSHEAD J E.Finite element model updating in structural dynamics[M].Amsterdam:Kluwer Academic Publishers,1995.
[4] 张德文,魏阜旋.模型修正与破损诊断[M].北京:科学出版社,1999.
[5] 林红,陈国明,朱本瑞,等.海洋石油平台结构全寿命周期动态鲁棒性分析[J].石油学报,2015,36(2):246-252.LIN Hong,CHEN Guoming,ZHU Benrui,et al.Dynamic robustness analysis of offshore platforms for the whole service life cycle[J].Acta Petrolei Sinica,2015,36(2):246-252.
[6] IMREGUN M,VISSER W J.A review of model updating techniques[J].The Shock and Vibration Digest,1991,23(1):9-20.
[7] MODAK S V,KUNDRA T K,NAKRA B C.Comparative study of model updating methods using simulated experimental data[J].Computers & Structures,2002,80:437-447.
[8] MOTTERSHEAD J E,FRISWELL M I.Model updating in structural dynamics:a survey[J].Journal of Sound and Vibration,1993,167(2):347-375.
[9] 夏樟华.基于静动力的桥梁结构有限元模型修正[D].福州:福州大学,2006.XIA Zhanghua.Finite element model updating based on static and dynamic bridge structures [D].Fuzhou:Fuzhou University,2006.
[10] 孙正华,李兆霞,韩晓林.大跨桥梁索塔有限元模型修正[J].工程抗震与加固改造,2006,28(1):50-54.SUN Zhenghua,LI Zhaoxia,HAN Xiaolin.Finite element model updating for the tower of long-span bridges [J].Earthquake Resistant Engineering and Retrofitting,2006,28(1):50-54.
[11] YUEN K V.Updating large models for mechanical systems using incomplete modal measurement [J].Mech Sys Signal Process,2012,28:297-308.
[12] 刘爱霞,石湘,李华军.导管架式海洋平台模型修正技术的研究[D].青岛:中国海洋大学,2006.LIU Aixia,SHI Xiang,LI Huajun.The studies on model updating for offshore platforms [D].Qingdao:Ocean University of China,2006.
[13] 李英超.基于模态参数识别的海洋平台结构模型修正技术研究[D].青岛:中国海洋大学,2012.LI Yingchao.Model updating of offshore platform structures based on model parameter identification [D].Qingdao:Ocean University of china,2012.
[14] WANG S H,LI Y,LI H.Structural model updating of an offshore platform using the cross model cross mode method:an experimental study [J].Ocean Engineering,2015(97):57-64.
[15] 刘超.导管架平台动力特性实验研究[D].天津:天津建筑大学,2014.LI Chao.The dynamic characteristics of jacket platform experimental research [D].Tianjin:Tianjin Architectural University,2014.
[16] GAO X,LING X Z,TANG L,et al.Soil-pile-bridge structure interaction in liquefying ground using shake table testing [J].Soil Dynamics & Earthquake Engineering,2011,31(7):1009-1017.
[17] 王济,胡晓.MATLAB在振动信号处理中的应用[M].北京:中国水利水电出版社,2006.
[18] 杨佑发,程亚鹏,李华新.环境激励下基于经验模式分解的结构模态参数识别方法[J].土木工程学报,2013,46(增2):73-78.YANG Youfa,CHENG Yapeng,LI Huaxin.Empirical mode decomposition based method of structural modal parameter identification under ambient excitation [J].China Civil Engineering Journal,2013,46(sup2):73-78.
[19] 吕涛,徐长航,陈国明,等.基于振动响应的导管架平台极限承载能力分析[J].中国石油大学学报(自然科学版),2016,40(3):155-162.Lü Tao,XU Changhang,CHEN Guoming,et al.Ultimate bearing capacity analysis of jacket platforms based on vibration response[J].Journal of China University of Petroleum (Edition of Natural Science),2016,40(3):155-162.
[20] ALLEMANG R J,PHILLIPS A W.Un-weighted and weighted versions of the modal assurance criterion (MAC) for evaluation of modal vector contamination [M].Berlin:Springer International Publishing,2014.
[21] 袁爱民,戴航,孙大松.考虑边界条件约束和参数灵敏度的斜拉桥有限元模型修正[J].应用基础与工程科学学报,2010,18(6):900-909.YUAN Aimin,DAI Hang,SUN Dasong.Finite element model updating for a cable-stayed bridge considering the boundary condition constraint and parameter sensitivity[J].Journal of Basic Science and Engineering,2010,18(6):900-909.
[22] LIU C S.Trial equation method based on symmetry and applications to nonlinear equations arising in mathematical physics [J].Foundations of Physics,2011,41(5):793-804.