ELASTIC MODULUS MEASUREMENT OF STRAND WITRE BY DIGITAL IMAGE CORREALTION

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.