数字图像相关测量钢绞线弹性模量的应用研究

ELASTIC MODULUS MEASUREMENT OF STRAND WITRE BY DIGITAL IMAGE CORREALTION

  • 摘要: 该文利用非接触式数字图像相关方法测量了预应力钢绞线的弹性模量。测量过程中用CCD相机记录不同载荷下钢绞线表面的数字图像,再利用数字图像相关方法对所采集的序列数字图像进行分析从中精确提取不同载荷下钢绞线表面的纵向平均正应变。根据试验机的载荷信息、钢绞线的参考截面积和由数字图像相关方法测量的平均正应变绘制出钢绞线的应力-应变曲线,并对应力-应变曲线进行线性拟合计算出钢绞线的弹性模量,为验证该文方法的精度,研究中对钢绞线进行重复试验,通过获得5组弹性模量数据,并将测量结果与接触式引伸计测量结果进行了比较,两者符合得很好。实验结果表明数字图像相关方法可用于预应力钢绞线弹性模量的快速、精确测量。

     

    Abstract: The elastic modulus of strand wires under uniaxial tension is measured using a digital image correlation method (DIC) in this paper. The surface images of the strand wire surface subjected to various loadings were captured using a CCD camera. DIC is subsequently used to obtain displacement field by correlating the images captured before and after deformation, and then the average tensile strain is obtained by fitting the displacement using a linear plane. The slope of each set of applied stress versus measured strain data is calculated by least-squares linear regression. The elastic moduli obtained from DIC, are compared to that determined from the extensometer, which shows that they are in good accordance with each other. Experimental results clearly show that DIC is suitable for accurate measurement of the elastic modulus of strand wire.

     

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