Research on quantitative evaluation of rebar stress based on weak magnetic effect

In order to explore an evaluation method for nondestructive testing of the rebar stress, the weak magnetic field test of the rebar stress was carried out in this paper. The evolution characteristics of the magnetic induction component By along the length direction of the rebar under tensile load were analyzed. The value of the root mean square gradient of the axial magnetic induction intensity KRMS_e was introduced. The law of linear decline of characteristic parameters with the stress in the elastic stage was revealed. The relationship between the feature parameters and the lift-off value of the sensor was further analyzed, and the lifting effect of the feature parameters was modified. Based on the correction of the lifting effect, the influence of the initial magnetization on the weak magnetic detection of stress was removed through the simulation test. The naive Bayesian classification algorithm is introduced into the stress classification evaluation. The statistical analysis of the relationship between the modified characteristic parameter KRMS_ecN and stress is carried out. A stress classification evaluation model is established based on the maximum of posteriori probability. The model can classify the rebar stress in specific ranges with high accuracy. This study provides a new evaluation method for nondestructive testing of the rebar stress state.