Papers by Keyword: Hysteresis Loss

Abstract: A styrene-butadiene rubber having a gradient crosslink density in the thickness direction was simply prepared by vulcanizing under a temperature gradient to study its mechanical properties and swelling behavior. The graded rubber exhibited considerable strain recovery after stress removal despite having a low crosslinked part. Notably, the graded rubber also manifested greater hysteresis loss during cyclic test compared to a homogeneously crosslinked rubber, even though they had similar initial moduli. Furthermore, anomalous swelling behavior was observed in the graded rubber. The graded rubber exhibited shape transformation upon swelling. The mechanism was thoroughly explained using gel swelling theory under constraints. This must be a common phenomenon in graded rubbers with a crosslink gradient in the thickness direction. This comprehensive research provides a novel approach for material design with tailored properties and promising applications for this potential material.

Abstract: Multi-filamentary Nb₃Sn strand for ITER has been successfully fabricated by a conventional internal-tin (IT) route at Western Superconducting Technologies, Co. Ltd. All the performances of the IT Nb₃Sn strand is able tomeet the ITER specifications. In 2010, one hundred kilograms of IT Nb₃Sn strand has been cabled, jacketed and integrated into conductor sample titled with TFCN2 by ASIPP in China and tested in CRPP, Switzerland. After 1200 cycles warm-up and cooling down, T_cs of the TFCN2 Sultan sample at 10.78 T, 4.5 K are 6.35 K for the left leg and 6.37 K for the right leg, respectively, which is larger than the ITER lower limit of 5.7 K. This is the first successful Sultan sample made of Chinese Nb₃Sn strand. In 2011, the influence of applied axial strain on critical current (I_c) was investigated using TFCN2 strand in the University of Twente, the Netherland. The irreversible degradation of I_c starts around +0.23% tensile intrinsic strain. The heat treatment influence of the duration at 650 °C on microstructure and performance was also studied. It was found that the fraction of un-reacted Nb after heat treatment is dependent on the position in the cross section. The hysteresis loss increases much faster than I_c when the duration at 650 °C increased.

Abstract: A novel dynamic electromagnetic induction heater for water treatment system is introduced in this paper, and its structure and operation mechanism is given. The heater converts input mechanical energy into various forms of heat energy completely, including the hyseresis loss, eddy current loss, copper loss and so on, and the mathematical model of loss is established based on fundamental electromagnetic field theory. By the finite element analysis, the above three kinds of loss are calculated at different rotation speed, as well as each of the percentage of total loss. At last, the temperature field and heat flux distribution of heater are calculated.

Abstract: Cold rolled grain oriented (CRGO) steel was deformed by uni-axial tensile loading in three different directions: Rolling Direction (RD) (110) , Transverse Direction (TD) (110) and 45° to RD (110) . Deformation behavior was found to be different for the different directions of loading. Such differences were biased by the heat flattening coating and could be captured, effectively, through discrete dislocation dynamics simulations. Results from texture and micro-texture studies, mechanical tests and magnetic measurements show a clear relationship between strain hardening exponent (n) and degradation in magnetic properties (watt loss and permeability). These were also related to misorientation developments, relative recovery and deviations from ideal Goss orientation.

Abstract: The Fe-Si-Al soft magnetic composites were produced by cold pressing of water-atomized Fe-Si-Al powder using organic binder. The effect of shaping pressure, annealing temperature, magnetic annealing and dielectric content on properties of Fe-Si-Al soft magnetic composites was investigated. The results showed that increasing shaping pressure increases density and radial crushing strength of Fe-Si-Al soft magnetic cores, and decreases coercivity and total loss. Increasing annealing temperature can increase effective permeability and decrease total loss owing to decreasing hysteresis loss, and over-annealing (＞660°C) can deteriorate magnetic properties. The magnetic annealing can decrease total loss of Fe-Si-Al magnetic powder core. Increasing dielectric content can reduce the eddy current loss of Fe-Si-Al magnetic powder core and decrease the real part of permeability. Fe-Si-Al magnetic powder core with shaping pressure of 1800 MPa, annealing temperature of 660 °C and dielelctric content of 0.7% presented the optimum magnetic properties with an effective permeability of 127, a total loss of 78mW/cm3 and a radial crushing strength of 18MPa.

Abstract: The constitutive equation of rubber is derived by employing a nonaffine molecular chain network model for an elastic deformation behavior and the reptation theory for a viscoelastic deformation behavior. The results reveal the roles of the individual springs and dashpot, and the strain rate dependence of materials and disentanglement of molecular chains in the monotonic and cyclic deformation behaviors, particularly softening and hysteresis loss, that is, the Mullins effect, occurring in stress-stretch curves under cyclic deformation processes.

Abstract: Core loss of soft magnetic powder cores have been focused on to achieve high efficiency of power supplies. In this study the effects of crystal grain size on core loss were investigated by changing heat treatment conditions. It was found that core loss is influenced by crystal grain size because eddy current loss decreased and hysteresis loss increased by making crystal grain size smaller, and it is also influenced by the frequency and particle size.

Abstract: Finemet type materials show extremely soft magnetic behavior with excellent and in wide range on-demand variable macroscopic parameters [1]. Requirements for the most important magnetic parameters (e.g. permeability, coercitive force, saturation, loss) are determined by the targeted applications. We report results on the optimization of crystallization treatments and parameter tailoring by magnetic field induced anisotropy. As compared to the most widely used magnetic materials our samples have parameters of real measure of excellence.