摘要
鉴于传统数字图像相关(DIC)方法采用的布点方式(水平成行,垂直成列)很可能会将一些测点分布在散斑质量较差的位置,提出了一种基于测点优化、Newton-Raphson(N-R)迭代与粒子群优化(PSO)算法的DIC方法。首先,通过在原始测点周围寻找散斑质量较好的区域来优化测点位置;然后,采用基于N-R迭代与PSO的粗细搜索方法计算优化后(非均匀分布)测点的位移场;最后,采用二维格林样条插值算法对该位移场进行插值以获得原始测点处的位移场,再由中心差分方法获得应变场。对3幅散斑质量差别较大的散斑图上的测点进行了优化,并将传统方法和提出方法获得的应变的各种结果进行了比较。研究发现,当样本子区尺寸在21~41 pixel之间时,对于平均灰度梯度处于10~20 pixel^(-3),且预加应变量处于0.01~0.05之间的散斑图,采用该方法可以获得较好的测量结果,这与优化测点位置有关。若采用该方法仅对原始测点中分布在散斑质量较差位置处的那些测点进行优化,有望获得更为理想的测量结果。
In traditional Digital Image Correlation(DIC)methods,points are regularly distributed,that is,points are parallelin horizontal and vertical directions.Thus,a few points can be distributed in positions where speckle qualities are bad.Inthis paper,a digital image correlation method based on the optimization of positions of points,Newton-Raphson(N-R)iteration and particle swarm optimization is proposed.Firstly,the positions of original points are optimized;secondly,the displacement field for the irregular optimal points is obtained by use of the N-R iteration and PSO;finally,thedisplacement field is interpolated using two-dimensional Green’s function-based interpolator to obtain the displacementfield at regularity distributed points,and then,the strain field is obtained by use of the central difference method.For threespeckle images where speckle qualities are greatly different,positions of points are optimized,and comparisonsbetween the present and traditional results are conducted.It is found that the present method has reasonable accuracy forspeckle images with the strain of0.01~0.05,the size of subsets of21~41pixel,and the mean intensity gradient of10~20pixel-3,which is related to the point optimization.It is expected that high accurate results can be obtained using the presentmethod if only the positions of points distributed at positions with bad speckle qualities are optimized.
作者
张楠
王学滨
杜亚志
ZHANG Nan;WANG Xuebin;DU Yazhi(College of Mechanics and Engineering, Liaoning Technical University, Fuxin, Liaoning 123000, China;Institute of Computational Mechanics, Liaoning Technical University, Fuxin, Liaoning 123000, China)
出处
《计算机工程与应用》
CSCD
北大核心
2017年第3期193-200,共8页
Computer Engineering and Applications
基金
国家自然科学基金(No.51374122)
高等学校博士点专项科研基金联合资助项目(No.20132121110006)
辽宁省科学事业公益研究基金资助项目(No.GY2014-C-008)
关键词
数字图像相关方法
测点位置
优化
平均灰度梯度
散斑质量
格林样条插值
digital image correlation method
positions of points
optimization
mean intensity gradient
speckle quality
Green’s function-based interpolator
