Measurement and Modeling of Magneto-elastic and Magneto-thermal Behavior of High-Strength Steels

The accurate computation of the non-linear stress-induced hysteretic magnetic behavior of high-strength steels is a significant challenge. This is important for degaussing design for Navy vessels needing to avoid detection by magnetic anomaly detection (MAD) systems. During normal operation, Navy vessels experience stresses and intricate shifts in their magnetic states, leading to nonlinear and hysteretic changes in their magnetic signatures. The absence of comprehensive physics-based models of this phenomenon hinders the development of magnetic signature reduction systems. As a result, the Navy and ship-building industry often rely on empirical methods to predict stress or thermal induced magnetization that lack the depth and reliability of a physics-based approach to address this critical issue, leaving modern ships vulnerable to MAD systems. Our research team is poised to provide the ability to both measure and model stress and thermal induced magnetization of high-strength steels over wide ranges of field histories and for high stresses. The University of Colorado Denver Magnetic Materials Laboratory (UCD-MML) is equipped with a state-of-the art facility capable of performing highly accurate measurements of stress-induced magnetization for both normal and shear stresses in excess of 400 MPa over a wide range of fields ranging from the levels of Earth’s field to near saturation. Experiments can be done as isothermal measurements, or with dynamic temperature conditions. Our research team has a proven track record of developing advanced models for dynamic magnetic hysteresis and stress-induced magnetization under moderate stress conditions. The proposed work aims to deliver accurate models for magneto-stress and magneto-thermal-induced magnetization validated by experimental evidence. These models will be integrated into a volume integral equation based software with a nonlinear solver, to provide the accurate prediction of the underwater magnetic signature of full-scale Navy vessels across a broad range of applied fields and stresses. This advancement will facilitate the design of a state-of-the-art degaussing system, ensuring the survivability of next-generation submarines against MAD systems. This STTR proposal will provide these capabilities by: a) Developing physics-based models that accurately model non-linear magneto-electric and magneto-thermal hysteresis for an arbitrary magnetic history and for large stresses; b) Extracting physical parameters for these models using controlled experiments that vary applied magnetic fields, mechanical stresses (normal and shear), and temperature; c) Validating the models through the comparison of measured and predicted data; and d) Implementing these models in a non-linear transient magnetic field solver capable of simulating arbitrarily shaped structures under varying magnetic field, mechanical stresses and temperatures.