应用数字散斑相关法测量结构振动位移和频率
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摘要
将数字散斑相关法应用于测量结构振动的位移和频率,对振动结构标记人为散斑或者利用结构本身较明显的天然散斑作为目标点,利用摄像机连续采集一系列数字图像,结合数字散斑相关法,对目标点散斑进行识别,计算其在图像中位置的变化以获得目标点位移,进而通过FFT变化得到频率。在振动台水平正弦激励某模型结构的实验中,通过与位移计测量结果的比较证明,所提出的方法是可行的,并且具有工程可接受的精度。通过试验详细探讨了散斑的选取对测量结果的影响。本文方法可方便的应用于桥梁、建筑、空间结构等土木工程结构的振动位移与频率的非接触、全景式多点同时监测。
The Digital Speckle Correlation Method(DSCM) was applied to the measurement of structural vibration displacement and frequency.The procedures for this measurement technique include:(1) to mark one or more artificial speckles or to select some existing obvious natural speckles on the vibrating structure as the movement target;(2) to get a series of continuous digital images from the video for capturing the structural vibration;(3) to obtain the displacement of movement target by locating the selected speckle in each image using DSCM;(4) to obtain the vibration frequency using Fast Fourier Transformation(FFT) from the displacement time-history.This method is proved to be feasible by comparing the results with those obtained by a displacement meter for sinusoidal horizontal vibrations of scaled structures excited by a vibration platform.The measurement accuracy is acceptable for engineering applications.The influence of speckle selection on the measurement accuracy was experimentally investigated in detail.The presented technique can be conveniently applied to the non-contact and panoramically simultaneous multi-target measurement of vibration displacement and frequency of civil engineering structures such as bridges,buildings and space structures.
The Digital Speckle Correlation Method(DSCM) was applied to the measurement of structural vibration displacement and frequency.The procedures for this measurement technique include:(1) to mark one or more artificial speckles or to select some existing obvious natural speckles on the vibrating structure as the movement target;(2) to get a series of continuous digital images from the video for capturing the structural vibration;(3) to obtain the displacement of movement target by locating the selected speckle in each image using DSCM;(4) to obtain the vibration frequency using Fast Fourier Transformation(FFT) from the displacement time-history.This method is proved to be feasible by comparing the results with those obtained by a displacement meter for sinusoidal horizontal vibrations of scaled structures excited by a vibration platform.The measurement accuracy is acceptable for engineering applications.The influence of speckle selection on the measurement accuracy was experimentally investigated in detail.The presented technique can be conveniently applied to the non-contact and panoramically simultaneous multi-target measurement of vibration displacement and frequency of civil engineering structures such as bridges,buildings and space structures.
引文
[1]蔡坤.数字散斑相关法非接触动态位移与振动测量技术研究[D].杭州:浙江大学,2005.CAI Kun.Research on Digital Speckle Correlation Methodfor Non-contact Dynamic Displacement and VibrationMeasurement Technology.[D].Hangzhou:ZhejiangUniversity,2005.
[2]PETER W H,RANSON W F.Digital Imaging Techniquein Experimental Stress Analysis[J].OpticalEngineering,1982,21(3):427-431.
[3]杨静.白光散斑的位移测量[J].应用科技,2002,29(9):49-51.YANG Jing.Displacement Measurement Based onSpeckles of White Light Diffraction[J].Applied Scienceand Technology,2002,29(9):49-51.
[4]芮嘉白,金观昌,徐秉业.一种新的数字散斑相关方法及其应用[J].力学学报,1994,26(5):599-607.RUI Jiabai,JIN Guanchang,XU Bingye.A New DigitalSpeckle Correlation Method and Its Application[J].ActaMechanica Sinica,1994,26(5):599-607.
[5]张军辉,冯平,蔡增伸.数字散斑相关法应用于非接触应变的测量方法[J].理化检验-物理分册,2006,42(9):457-459.ZHANG Junhui,FENG Ping,CAI Zengshen.BriefIntroduction of Digital Speckle Correlation Method for Non-Contact Strain Measurement[J].Physical Testing andChemical Analysis Part A:Physical Testing,2006,42(9):457-459.
[6]冈萨雷斯.数字图像处理(MATLAB版)[M].北京:电子工业出版社,2009.GONZALEZ R C.Digital Image Processing UsingMATLAB[M].Beijing:Publishing House of ElectronicsIndustry,2009.
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[9]郭海鸿,李晓星.非接触应变测量的数字散斑相关方法的研究[J].现代制造工程,2007(11):96-98.GUO Haihong,LI Xiaoxing.Research on Digital SpeckleCorrelation Method for Non-contact Strain Measurement[J].Modern Manufacturing Engineering,2007(11):96-98.
[10]王言磊,欧进萍.散斑图像相关数字技术在海洋平台结构模型振动位移测量中的应用[J].世界地震工程,2006,22(1):94-98.WANG Yanlei,OU Jinping.Application of a DigitalSpeckle Image Correlation Technique to VibrationDisplacement Measurement of an off-shore Platform Model[J].World Earthquake Engineering,2006,22(1):94-98.
[11]罗军辉,冯平,哈力旦A.MATLAB7.0在图像处理中的运用[M].北京:机械工业出版社,2007.LUO Junhui,FENG Ping,HALITAN A.Application ofMATLAB7.0 to Digital Image Process[M].Beijing:China Machine Press,2007.
[12]李玲,涂熙,王磊,等.桁梁局部破断试验中动位移的数字图像测量[J].结构工程师,2010,26(1):113-117.LI Ling,TU Xi,WANG Lei,et al.Digital ImageProcessing Technique for Dynamic Displacement in Truss-beam Local Failure Test[J].Structural Engineers,2010,26(1):113-117.
[13]乔英娟,王哲人,陈静云.沥青结构层芯样分层变形的数字图像测量方法[J].公路交通科技,2007,24(10):11-15.QIAO Yingjuan,WANG Zheren,CHEN Jingyun.DigitalImage Processing Technique for Measurement of CoursedDeformation of Asphalt Pavement Core Samples[J].Journal of Highway and Transportation Research andDevelopment,2007,24(10):11-15.
[14]LEE J J,SHINOZUKA M.Real-time DisplacementMeasurement of a Flexible Bridge Using Digital ImageProcessing Techniques[J].Experimental Mechanics,2006,46(1):105-114.
[2]PETER W H,RANSON W F.Digital Imaging Techniquein Experimental Stress Analysis[J].OpticalEngineering,1982,21(3):427-431.
[3]杨静.白光散斑的位移测量[J].应用科技,2002,29(9):49-51.YANG Jing.Displacement Measurement Based onSpeckles of White Light Diffraction[J].Applied Scienceand Technology,2002,29(9):49-51.
[4]芮嘉白,金观昌,徐秉业.一种新的数字散斑相关方法及其应用[J].力学学报,1994,26(5):599-607.RUI Jiabai,JIN Guanchang,XU Bingye.A New DigitalSpeckle Correlation Method and Its Application[J].ActaMechanica Sinica,1994,26(5):599-607.
[5]张军辉,冯平,蔡增伸.数字散斑相关法应用于非接触应变的测量方法[J].理化检验-物理分册,2006,42(9):457-459.ZHANG Junhui,FENG Ping,CAI Zengshen.BriefIntroduction of Digital Speckle Correlation Method for Non-Contact Strain Measurement[J].Physical Testing andChemical Analysis Part A:Physical Testing,2006,42(9):457-459.
[6]冈萨雷斯.数字图像处理(MATLAB版)[M].北京:电子工业出版社,2009.GONZALEZ R C.Digital Image Processing UsingMATLAB[M].Beijing:Publishing House of ElectronicsIndustry,2009.
[7]邓薇.MATLAB函数速查手册[M].北京:人民邮电出版社,2009:313-321.DENG Wei.Fast-searching Manual of MATLAB Function[M].Beijing:Posts and Telecom Press,2009:313-321.
[8]闫海涛,王鸣,赖方明,等.数字散斑相关法测量连续位移的原理与实验[J].南京师范大学学报:自然科学版,2006,29(2):44-47.YAN Haitao,WANG Ming,LAI Fangming,et al.Principle and Experiment of Digital SpeckleAutocorrelation Measuring Seriate Displacement[J].Journal of Nanjing Normal University:Natural Science,2006,29(2):44-47.
[9]郭海鸿,李晓星.非接触应变测量的数字散斑相关方法的研究[J].现代制造工程,2007(11):96-98.GUO Haihong,LI Xiaoxing.Research on Digital SpeckleCorrelation Method for Non-contact Strain Measurement[J].Modern Manufacturing Engineering,2007(11):96-98.
[10]王言磊,欧进萍.散斑图像相关数字技术在海洋平台结构模型振动位移测量中的应用[J].世界地震工程,2006,22(1):94-98.WANG Yanlei,OU Jinping.Application of a DigitalSpeckle Image Correlation Technique to VibrationDisplacement Measurement of an off-shore Platform Model[J].World Earthquake Engineering,2006,22(1):94-98.
[11]罗军辉,冯平,哈力旦A.MATLAB7.0在图像处理中的运用[M].北京:机械工业出版社,2007.LUO Junhui,FENG Ping,HALITAN A.Application ofMATLAB7.0 to Digital Image Process[M].Beijing:China Machine Press,2007.
[12]李玲,涂熙,王磊,等.桁梁局部破断试验中动位移的数字图像测量[J].结构工程师,2010,26(1):113-117.LI Ling,TU Xi,WANG Lei,et al.Digital ImageProcessing Technique for Dynamic Displacement in Truss-beam Local Failure Test[J].Structural Engineers,2010,26(1):113-117.
[13]乔英娟,王哲人,陈静云.沥青结构层芯样分层变形的数字图像测量方法[J].公路交通科技,2007,24(10):11-15.QIAO Yingjuan,WANG Zheren,CHEN Jingyun.DigitalImage Processing Technique for Measurement of CoursedDeformation of Asphalt Pavement Core Samples[J].Journal of Highway and Transportation Research andDevelopment,2007,24(10):11-15.
[14]LEE J J,SHINOZUKA M.Real-time DisplacementMeasurement of a Flexible Bridge Using Digital ImageProcessing Techniques[J].Experimental Mechanics,2006,46(1):105-114.
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