Finite element analysis of high field permanent magnet mechanism using vector Preisach hysteresis model
This paper presents a method to simulate abnormal magnetizations in high field permanent magnet mechanism. Abnormal magnetizations including local saturation, local demagnetization and rotational magnetization occur in the assembly process of high field permanent magnet mechanism. Combining an anisotropic vector Preisach model and finite element analysis, abnormal magnetizations are simulated comprehensively. The method only requires the data of limiting magnetic hysteresis loops of the material along easy and hard axis, so the application of vector Preisach model becomes convenient and efficient. A sixteen elements enhanced magic ring is designed and the process of assembling is simulated, which verify the validity of the presented method.
Vector hysteresis model for unoriented magnetic materials
Presented in this paper is a vector hysteresis model for unoriented magnetic materials expanded from the magnetization-dependent Preisach model. Namely, the Preisach elements have rotational capabilities and they memorize their directions, and the Preisach plane is divided into reversible, irreversible regions and the regions maintaining their previous states. By integrating the Preisach plane vectorially for the magnitude-varying rotating field, the hysteresis phenomena such as the directions and magnitude of the magnetization and the hysteresis losses can be calculated. >
Experimental investigation of the geotechnical properties and microstructure of lime-stabilized saline soils under freeze-thaw cycling
Abstract The Song-Nen Plain in northeastern China holds one of the three largest expanses of soda saline-alkali soil in the world. Due to its disadvantageous geotechnical properties, the saline soil in this area is unable to meet the needs of construction projects. This study evaluates the stabilizing effect of adding lime to such soils. Specifically, it investigates how the physicochemical and mechanical properties and microstructure of soda saline-alkali soil are altered by lime and how these changes are affected by both freeze-thaw cycling and the duration of curing. The results reveal that adding lime to saline soil transforms clay particles into sand and silt particles and causes the pore size distribution (PSD) to become bimodal, with small-pore and macropore populations. An increase in lime content leads to an increase in the unconfined compressive strength (UCS) but a gradual decrease in both the cation exchange capacity (CEC) and plastic index. Freeze-thaw cycles break up coarse particles and aggregate finer particles, increasing the diameter of macropores and decreasing the USC; however, the effect on specimens with >9% lime is negligible. It is further shown that the geotechnical properties of the soil change immediately after the addition of lime, indicating that the cation exchange reaction takes place very quickly. Furthermore, the pozzolanic reaction leads to an increase in the percentage of sand-sized particles and a decrease in porosity after 28 days of curing. Overall, these results indicate that it is feasible to use lime to improve the engineering properties of soda saline-alkali soil in this area.