Whole-field Measurement of Strain Based on Digital Speckle Correlation Method

Traditionally extensometer has been used to measure the tensile strain to determine mechanical properties such as elastic modulus, yield and tensile strength. But it can only measure the average strain within the gauge length and can not produces the information on the strain distribution inside two knife point. This paper presents a novel method which uses digital speckle correlation technique, and produces whole-field strain for a better understanding of material behavior. It offers a significant advantage over conventional techniques with an extensometer in tensile test. The measurement results are presented with a comparison of the traditional method, and the data evaluation method is discussed in detail. This paper demonstrates the capabilities of technique for both quantitative and qualitative strain measurement in a whole field environment, which is almost impossible with the traditional method.