Steel structures are widely used in railway infrastructures.Their stress state is the most important determinant of the safety of these structures.The elasto-magnetic (EM) sensor is the most promising for stress monitoring of in-service steel structures.Nevertheless,the necessity of magnetic excitation to saturation due to the use of a secondary coil for signal detection,keeps from its engineering application.In this paper,a smart elasto-magneto-electric (EME) sensor using magneto-electric (ME) sensing units to take the place of the secondary coil has been exploited for the first time.The ME sensing unit is made of ME laminated composites,which has an ultrahigh ME voltage coefficient and can measure the magnetic induction simply and precisely.Theoretical analysis and characterization experiments firstly conducted on the ME laminated composites showed that the ME sensing units can be applied in the EM sensor for improved performance in stress monitoring.A tension test of a steel bar was carried out to characterize our smart EME sensor and the results showed high accuracy and sensitivity.The present smart EME sensor is a promising tool for stress monitoring of steel structures in railway and other civil infrastructures.
Whether the Terfenol-D rod should be laminated is of concern at the beginning of designing a magnetostrictive actuator for dynamic applications. Lamination can reduce the eddy current loss,but also decrease the stiffness of the GMM rod. The conventional way by is complicated FEM(Finite-Element Method) or one's experience. In this article an analytical approach of magnetic field distribution in the cross-section of the rod was described,and it was introduced as a reference method to judge if the Terfenol-D rod should be laminated. Numerical evaluation and experimental results proved the rationality and availability of the approach.
