Computational Framework for Magnetic Sensing in Structural Health Monitoring Applications via Magnetic Shape Memory Alloys

In the field of structural health monitoring (SHM), innovative methods of non-destructive evaluation (NDE) are currently being investigated for the purpose of enabling safer, longer lasting structures. While current SHM is dominated by acoustic emission and vibration-based methods, it would be desirable to combine NDE techniques with existing structural reinforcement techniques and allow these two functionalities to combine toward enhancing structural service life. Magnetic shape memory alloys (MSMAs) have differing magnetic properties at different phases related to their stress/strain state. Stress-induced phase transformations in embedded metallic wires, rods, or cables as caused by failure in a surrounding concrete matrix can be correlated to changes in MSMA magnetic properties. A computational model is developed using ABAQUS and COMSOL Multiphysics to evaluate the development of stress-induced martensite (SIM) due to internal damage in a load-bearing concrete-MSMA block composite, which is then shown to lead to a quantitative change in an externally applied magnetic field. This external change in the applied magnetic field, caused by internal damage and the initiation of a local region of SIM, is then used to locate internal damage via measurements of the magnetic flux density on the external surface of the structure. The computational results quantitatively demonstrate a method to locate SIM regions in embedded MSMAs, thus identifying internal structural damage