engleski

Mathematical modeling of influence parameters during formation and propagation of the Lüders bands

In this study, an analysis of the influence parameters measured by the static tensile test, thermography and digital image correlation was performed during formation and propagation of the Lüders bands. A new approach to predict stresses, maximum temperature changes and strains during the Lüders band formation and propagation is proposed in this paper. Application of the obtained mathematical models of influence parameters gives a clear insight into the behavior of niobium microalloyed steel at the beginning of the plastic flow, which can improve product quality and reduce costs during the forming of microalloyed steels with the appearance of the Lüders bands. Obtained models of influential parameters during formation and propagation of the Lüders bands have been developed by regression analysis method. The proposed mathematical models showed low deviations of calculated results ranging from 1.34% to 12.37%. The local stress amounts, important in the forming of microalloyed steels since indicate surface roughness and plastic flow possibilities during Lüders band propagation, are obtained by the mathematical model. It was found that stress amounts increase during Lüders band propagation in the area behind the Lüders band front. The difference in stress amount between start of the Lüders band propagation and advanced Lüders band propagation is 25.53 MPa.

Lüders bands, Regression analysis, Microalloyed steel, Thermography, Digital image correlation

Glavni autor: Brlić, Tin