Abstract：The specimen made of thin steel sheets is easy to buckle when it is subjected to tensile and compressive load in low cycle fatigue tests. Limited to the specimen length, typical mechanical extensometers are not suitable for strain measurement, which is a technical difficulty in engineering practice. In this paper, a non-contact optical extensometer based on digital image correlation combined with a microscopic imaging lens and an anti-buckling restraint device is developed to achieve real-time monitoring of the strain in material surface. The sampling frequency of the dynamic strain measurement system using a common CCD camera with optimized algorithm can reach up to 60 Hz. This technique provides a solution for thin steel sheets and can be potentially applied in low cycle fatigue tests.
2017, Vol. 38 
