Validation of a new system for measuring material constants representing damage limits

Abstract

This paper describes a test for the determination of damage function limits. The proposed test consists of skew rolling of conical specimens. The test is carried out under real conditions to determine the crack initiation point, and then it is modelled numerically to determine the limit values of the damage function at the determined crack initiation point. This paper presents a methodology for the determination of limit values of the damage function on the example of C45 steel at three different temperatures, i.e. 950 °C, 1050 °C and 1150 °C. The research was carried out using the Oyane criterion as an example. The limit value of the damage function at 1000 °C was determined by regression using the calculated damage function values. The value of the damage function was adapted to a numerical model of a skew-rolling process of a bar with the deletion of elements, which took place when the limit value of the damage function determined in the test was exceeded. The numerically simulated skew rolling case was also realised in real conditions. Based on the results obtained from the skew rolling of bars, a quantitative and qualitative validation of the new damage function limit test was carried out.