作者：张伟列, 刘宇杰, 卢福聪, 孙轶君

作者单位：西南交通大学力学与工程学院, 四川 成都 610031

关键词：拉扭应变测量;数字图像;标记线;单相机

摘要：

针对在薄壁圆管试样拉扭多轴试验中因传统接触式拉扭引伸计量程较小且难以在刚度较小的试样上使用等问题，提出一种新的基于图像的单相机拉扭应变测量方法，在试样表面作4道标记线并使用相机记录试验过程中标记线的位置变化；然后利用Matlab软件进行图像处理和计算，通过研究图像上标记线与试样中轴线交点高度的改变，并结合标记线的斜率特征，实现试样表面的拉、扭应变测量。通过试验将该方法的结果与DIC的测量结果进行对比，两者的测量结果吻合较好，验证该方法的可靠性。与接触式引伸计相比，该方法测量范围大，可应用在低刚度试样上，且设备简单便携，易于应用。

A tensional-torsional strain measuring method for thin-walled tubular specimens based on digital image

ZHANG Weilie, LIU Yujie, LU Fucong, SUN Yijun

School of Mechanics and Engineering, Southwest Jiaotong University, Chengdu 610031, China

Abstract: In tensional-torsional experiments with thin-walled tubular specimen, the conventional contact type extensometer has small measuring range and is hard to use for low stiffness specimen. A new method of tensional-torsional strain measurement based on digital image of signal camera was proposed for thin-walled tubular specimen of multi-axial experiment. Firstly, four tag lines were drawn on the surface of specimen. Then the changes in tag lines were recorded by digital camera during the experimental process. Finally, the digital images were processed by Matlab program. The tensional strain and torsional strain could be calculated by the gradients of the tag lines and the height changes in the intersection points between medial axis and tag lines. Additionally, the results of proposed method were compared with results of DIC method for the same tensional-torsional test. The axial strain and torsional strain agreed well between the two methods. This method is proved to be reliable. Compared with contact type extensometer, the new method has wide measuring range and is easy to use for low stiffness specimen. Furthermore, the equipment of this method is simple and portable, thus this method is convenient to apply.

Keywords: tensional-torsional strain measurement;digital image;tag line;single camera

2016, 42(7): 20-23  收稿日期: 2015-8-3;收到修改稿日期: 2015-10-18

基金项目: 

作者简介: 张伟列(1990-),男,江苏南通市人,硕士研究生,专业方向为实验力学、数字图像测量。

参考文献

[1] PETERS W H, RANSON W F. Digital imaging techniques in experimental stress analysis[J]. Optical Engineering,1982,21(3):213427-213427.
[2] CHU T C, RANSON W F, SUTTON M A. Applications of digital-image-correlation techniques to experimental mechanics[J]. Experimental Mechanics,1985,25(3):232-244.
[3] SAVIC V, HECTOR L G, FEKETE J R. Digital image correlation study of plastic deformation and fracture in fully martensitic steels[J]. Experimental Mechanics,2010, 50(1):99-110.
[4] 杨笑丛,王进才,任向春,等. 材料轴向拉伸变形的图像精密测量研究[J]. 工程与试验,2014,54(1):72-75.
[5] 王庆有,于涓汇,郭青,等. 利用线阵CCD非接触测量材料变形量的方法[J]. 光电工程,2002,29(4):20-23.
[6] CELESTION O, BELÉN R, PEDRO A, et al. Application of close range photogrammetry to deck measurement in recreational ships[J]. Sensors,2009,9(9):6991-7002.
[7] XIA R B, ZHAO J B, LIU W J, et al. A robust recognition algorithm for encoded targets in close-range photogrammetry[J]. Journal of Information Science and Engineering,2012,28(2):407-418.
[8] 苏新勇,黄雪梅,朱明健. 数字近景工业摄影测量中标志点的识别与检测[J]. 制造业自动化,2014,36(9):31-33.
[9] 程朋乐. 面和装配的微小型零件视觉检测技术[J]. 电子测量与仪器学报,2013,27(2):151-155.
[10] 娄小平,吕乃光,邓文怡,等. 基于机器视觉复杂形状工件的非接触式测量方法[J]. 工具技术,2005,39(7):82-85.
[11] 晏晖,姜鹏,陈贝. 基于Matlab工具箱的数字图像处理技术[J]. 微计算机信息,2010,26(9):214-216.
[12] 梁原. 基于Matlab的数字图像处理系统研究[D]. 长春:长春理工大学,2008.