Measurement of the steady state tearing in thin sheets using the contactless system

Abstract

The purpose of the present paper is the diagnostic method of the steady state tearing tests in thin steel sheets. The camera-based contactless system was used in the experimental research. The MATLAB software was used for the processing of real-time images. The data collected in the experiments were used to establish the R-curves in terms of the CTOD (crack tip opening displacement) based resistance curves. The innovative techniques allow extracting a large amount of geometrical information about the entire tearing process and the crack tip development. The steady state tearing was evaluated using automotive steel sheets and the tearing resistance was determined for three grades of thin sheets. The paper describes a comprehensive method of obtaining the material properties necessary for modelling and simulation. The proposed methodology for the testing and evaluation of the steady state tearing is applicable to thin sheets. The measurement method within the test for the determination of the tearing resistance was based on the image analysis.