Accurately modeling the flow curve over a large strain range is crucial for predicting the flow stress behavior of high silicon steel undergoing strain hardening in the continuous cold rolling process. This study proposes a large strain flow curve model for high-silicon steel, a material commonly used in the cores of electromagnetic devices such as electric motors, generators, and transformers. This model was developed through a series of tensile tests on homogenously pre-strained specimens. Pilot cold rolling was performed at various thickness reduction ratios to impart different magnitudes of pre-strain to sheet-type tensile specimens. The proposed flow curve model was implemented in a VUHARD user-defined subroutine within Abaqus/Explicit, and the predicted roll separating forces were compared with those measured from the pilot cold rolling tests. The comparison demonstrated that the proposed flow curve model accurately captures the flow stress behavior of high-silicon steel at different strain rates over a large strain range, with an R-squared value of 0.9932. The predicted roll separating forces closely matched the measurements from the pilot cold rolling tests, with an average difference of 5.1%.

This study proposes an indirect approach that estimates roll force from motor current signals in a rolling mill. Motor current is first converted to motor torque using an induction-motor equivalent-circuit model, then to roll torque via the gear ratio, and finally to roll force through a torque-arm relationship. A laboratory-scale rolling mill was designed and fabricated to experimentally validate the approach. Two torque-conversion schemes were examined: Method A, which determines the slip of the induction motor from measured rpm and recalculated motor parameters, and Method B, which estimates slip from measured motor current and applies a finite element (FE)–based response surface function to calibrate the converted torque. The converted roll torques were validated against FE analysis, and the resulting roll forces were compared with load cell measurements under various rolling conditions. Deviation, defined as the average difference between the FE-predicted torque and the converted torques, ranged from −11.9% to 28.8% for Method A and −7.2% to 13.8% for Method B. Roll force deviations from measurements ranged from −14.1% to 14.9% for Method A and −3.7% to 14.2% for Method B. Method A provided a straightforward and computationally light conversion route but was more sensitive to rpm-measurement noise, whereas Method B yielded smoother temporal behavior at the cost of FE-based calibration. The results demonstrate that both methods can reproduce the overall evolution of roll torque and roll force using only motor-side measurements, offering a practical foundation for real-time monitoring in rolling mills where stand-by-stand load cells are unavailable.

Quality of High Volume Blast Furnace Slag Mortar Depending on Desulfurization Gypsum Treating Methods and Fine Aggregate Type Blast furnace slag powder;Desulfurized gypsum;Sieving;Heating;Recycled fine aggregate; In this research, based on the condition of using desulfurization gypsum(FGD) as a stimulator for high-volume blast furnace slag cement mortar, sieving and heating process methods of removing activated carbon in FGD were compared with the non-processed FGD and recycled and natural fine aggregates were compared for suitable aggregate to be used. According to the result of experiment, sieving with 0.3mm was more efficient than $500^{\circ}C$ heating for processing the FGD, and recycled fine aggregate showed more favorable result than natural fine aggregate at the FGD content was 5 to 10%. On the other hand, the mortar mixture including recycled fine aggregate had a high drying shrinkage, and absorption ratio, and thus specific limitations on applying recycled fine aggregate should be required.

View Video Presentation: https://doi.org/10.2514/6.2022-1069.vid Multicopter aerodynamics is numerically investigated in this study. The main objective is to understand unsteady aerodynamic loads and major unsteady flow structures for a multicopter. The open-source CFD solver OpenFOAM with the overset mesh method is used to resolve rotors with the stationary fuselage simultaneously. Tip vortices from multicopter rotors are influenced by adjacent rotors and the fuselage. Tip vortices from two counter-rotating rotors are merged to a vortex tube, and tip vortices are broken down to smaller structures when the tip vortex collides with the fuselage. This complex vortical structures induce the local inflow on the rotor blades. In addition, the rotor blade encounters the ground effect from the fuselage, when the rotor blade is passing above it. With these rotor-rotor and rotor-fuselage interactions, unsteady airloads on the rotor blade occur in every revolutions, and a multicopter experiences a 6/rev fluctuation of the aerodynamic forces.