Measurement of bearing capacity of steel road barrier flange via Barkhausen noise emission

Abstract

This paper reports about the bearing capacity of a steel road barrier flange and its non-destructive assessment via magnetic Barkhausen noise. Bearing capacity was investigated as a function of the variable degree of plastic straining accumulated in the flange. Plastic deformation was developed on the samples cut from the flange and loaded by uniaxial tension under different strain rates in order to model the dynamic behaviour of plastic deformation during the real collisions. The results of experiments demonstrate that the accumulation of plastic deformation expressed in terms of increasing dislocation density, and the corresponding hardness of the matrix, reduces the bearing capacity of the flange expressed in terms of notch toughness. This decrease is only gentle for the lower plastic strain and becomes steeper for higher strains. Barkhausen noise emission also drops down and MBN envelopes are shifted to higher magnetic fields along with increasing plastic straining as a result of increasing opposition of increasing dislocation density against domain walls motion. It was also found that MBN parameters strongly correlate with notch toughness and especially magnetic hardness is very sensitive for determination of the flange state not only under the high strain rates but also under the strong dynamic impacts as those expected in the high angle collisions. The study proposes the methodology in which the used flanges could be approved for their further use.