Experimental analysis of the piezomagnetic behavior of double-shear bolted connections of wire and arc additively manufactured steel

In this paper, the piezomagnetic behaviour of WAAM double-shear connection specimens were investigated. It aims to develop a damage monitoring method based on piezomagnetic effect for WAAM steel bolted connections. Eight WAAM steel coupons with two different print layer orientations were fabricated to measure the mechanical properties of WAAM materials. A total of 32 WAAM double-shear bolted connection specimens with two print layer orientations were designed to analyse the structural properties of WAAM members. A magnetic probe was used to monitor the variations of the piezomagnetic field. The evolutions of piezomagnetic field of transversal and longitudinal WAAM coupons were compared and analysed. Notably, it is found that piezomagnetic field manifests anisotropy consistent with the mechanical properties. The characteristics of five failure modes including net section tension, end-splitting, shear-out, bearing, block shear were discussed. The correlation between the magnetic field–displacement curve and the load-displacement curve was systematically examined. The characteristics of magnetic field of specimens failing by bearing were emphatically explored. The results show that bearing failure can be distinguished from other failure modes by monitoring the magnetic field. In addition, the evolution of magnetic field serves as a predictor of the ultimate capacity and failure of double-shear bolted connections.