Investigation on SMFL Field Distribution of Different Types of Rebars under Axial Tensile Failure Tests

Abstract

Structural safety performance is intricately tied to the stress level of rebars. The force-magnetic coupling relationship of rebar is a current focal point. Research gaps exist in the influence pattern of the appearance and shape of rebars on the mechanical and magnetic properties. This study conducted axial tensile failure tests on HRB400 ribbed rebars and HPB300 round rebars with different diameters. Variations in mechanical and magnetic indices were monitored and recorded to analyze the force-magnetic coupling effect in rebars. Results reveal that, concerning mechanical properties, increasing rebar diameter led to higher yield and ultimate strains, resulting in increased ultimate deformation. Ribbed rebars with a bumpy cross section differed from the smooth cross section of round rebars, leading to variations in the curves of tensile elongation percentage (l) versus section reduction percentage (r) for different rebar types. Regarding magnetic properties, the self-magnetic flux leakage (SMFL) intensity of ribbed rebar surpassed that of round rebar. SMFL curves in the elastic-plastic articulation stage exhibited contrast wave peaks, with rebar diameter positively correlating with the fluctuation range. Variations in leakage gradient curves indicated a stronger force-magnetic coupling relationship in the elastic and yielding stages and a weaker relationship in the strengthening stage. This research establishes the groundwork for nondestructive testing of rebar stress and enhances understanding of force-magnetic coupling in different rebar types.