摘要
利用激光散斑数字图像相关(Digital Image Correlation,DIC)技术能够实现金属微应变的无接触、原位测量,但激光散斑的像质如均匀性、灰度梯度、稳定性等对应变测量精度存在较大影响。为了提高激光散斑DIC技术测量金属应变的准确性和测量精度,本文针对激光器选型、激光波长、扩束系统、成像系统等进行了详细的设计、改进和测试。通过定量分析光学系统改进前后的散斑大小、占空比等像质评价参数,确定了激光散斑DIC技术的应变测量精度影响因素,并通过优化激光功率、曝光时间、接圈长度、像距等光路参数,获得了全视场范围分布更加均匀、像质更好的散斑图像,从而提高了激光散斑DIC技术测量应变的准确度和测量精度。利用激光散斑DIC技术实施了金属铝在非真空环境下从室温加热到360℃的热应变测量,测量结果与理论值吻合较好,而且随着温度的升高,测量结果的相对误差不断降低,证明了该方法在金属热应变检测中应用的可行性。
The digital image correlation method of laser speckle can be used to realize the non-contact and in-situ measurement of metal micro-strain,but the image quality of laser speckle,such as uniformity,gray gradient,stability and so on,has a great influence on the strain measurement accuracy.In order to improve the accuracy and precision of the DIC method of laser speckle for the measurement of metal strain,the laser selection,laser wavelength,beam expansion system and imaging system are designed,improved and tested in detail in this paper.Through the quantitative analysis of the image quality evaluation parameters such as speckle size and duty cycle before and after the improvement of the optical system,the factors affecting the strain measurement accuracy of laser speckle DIC method are determined.And by optimizing the parameters of the optical path such as laser power,exposure time,junction length,and image distance,the speckle images with more uniform distribution and better quality in full field were obtained,which improved the accuracy and precision of strain measurement by the laser speckle DIC method.Finally,the DIC method of laser speckle is used to measure the thermal strain of metal aluminum heated from room temperature to 360℃ in non-vacuum environment.The measured results are in good agreement with the theoretical values,and the relative error decreases with the increase of temperature,which proves the feasibility of this method in metal thermal strain measurement.
作者
张吴记
黄刚
潘志伟
张大乐
王俊松
黄生洪
汪卫华
杨锦宏
贺胜男
ZHANG Wuji;HUANG Gang;PAN Zhiwei;ZHANG Dale;WANG Junsong;HUANG Shenghong;WANG Weihua;YANG Jinhong;HE Shengnan(Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,Anhui,China;Department of Modern Mechanics,University of Science and Technology of China,Hefei 230027,Anhui,China)
出处
《实验力学》
CSCD
北大核心
2024年第1期65-74,共10页
Journal of Experimental Mechanics
基金
科技部重点研发计划资助项目(2019YFE03080400)
国家自然科学基金项目(11904007)。
关键词
激光散斑
数字图像相关法
原位测量
热应变测量
laser speckle
digital image correlation method
in-situ measurement
thermal strain measurement
