EXPERIMENTAL STUDIES OF SHEAR BAND FORMATION THROUGH TEMPERATURE-MEASUREMENTS AND HIGH-SPEED PHOTOGRAPHY

Observations are made during dynamic deformation of metals leading to adiabatic shear banding. The tests include measurements of local strain and local temperature rise. The temperature measurements are performed using an array of infrared sensitive, semiconductor photodiodes giving an average temperature increase of up to 600-degrees-C. Ultra-high speed photography shows that localization begins gradually then narrows into a fine shear band with strains of 10(3) and strain rates of 10(5)/s. Using the magnitude of geometric variations in the specimen as a parameter, analysis predicts with considerable accuracy the strain at which the shear band is triggered.