Modeling of magnetic properties of GO electrical steel based on Epstein combination and loss data weighted processing

The extended modeling of the magnetic properties of GO (Grain Oriented) electrical steel is presented in this paper which is based on a set of standard and scaled-down Epstein frames and a proposed two-level weighted processing of Epstein data, including the mean magnetic path length, specific magnetization loss and exciting power. The effects of excitation frequency, strip angle and ambient temperature on the results obtained from the Epstein frames are investigated. It is shown that using the proposed Epstein combination and the two-level weighted processing method is an efficient way of building a model for determining magnetic losses more realistically, hence, improving the value of Epstein strip measurement data

Injection water jet peening of carburised 18CrNiMo7-6 steel surfaces

A compressive residual stress field (CRSF) can improve the fatigue life of machined parts. Injection water jet peening is a new way of inducing compressive residual stress in the surface layer. A carburised 18CrNiMo7-6 gear steel was tested using injection peening under different conditions. The main variables included pressure, nozzle velocity and stand-off distance. The surface hardness was improved up to 63.4 HRC from its original hardness of 56.3 HRC. The maximum residual stress reached −1,240 MPa at a depth of 150 μm. The results also showed that pressure has the most dominant effect on the CRSF. Metallographic photos showed that the grain size was refined in the subsurface layer, a phase change having occurred because of the peening. It was also found that the average surface roughness was inversely influenced by peening, suggesting a new role for water jets in the finishing process

Hard milling of carburized and waterjet peened 18CrNiMo7-6 steel

Post-mixed waterjet peening is an effective treatment method for compressive residual stress field. After peening, the surface quality of the parts is low, and the hardness is usually higher than 60HRC. A fine manufacturing process should be carried out to obtain a satisfactory surface roughness without side effect on existing residual stress. In this article, the 18CrNiMo7-6 steel after carburization was subjected to post-mixed waterjet peening, the surface hardness was 66HRC and the maximum compressive residual stress was about 1242.86 MPa. Hard milling with CBN inserts were used to remove the rough surface layer of 18CrNiMo7-6. The hardness after milling has changed about 1-2HRC lower than that before cutting. When the cutting speed v c is 753.6 m/min, the feed speed v f is 0.04 mm/min and the cutting depth a p is 0.02 mm, compared to the original Ra 1.204 μm, the best surface roughness can reach Ra 0.0823 μm. When a p exceeds the maximum residual stress location point of 60 μm, the cutting effect will significantly change the residual stress. Considering the hardness, surface roughness and residual stress, the recommended milling parameters v f and a p should use the lower values, the range of v c should be 500–700 m/min and sufficient coolant is required during the cutting process

Effect of temperature-dependency of material properties on thermal shock fracture of solids associated with non-Fourier heat conduction

This paper investigates the thermal shock fracture behavior of a cracked semi-infinite medium with temperature-dependent material properties. The medium is subjected to a sudden temperature drop at its surface and all material properties are the functions of temperature. The temperature field and associated thermal stress in the medium without cracking are obtained by using the Laplace transform method and the numerical technology of Laplace inversion. The thermal stress intensity factors at the crack tip are obtained by using the weight function method. The thermal stress intensity factor and crack growth behavior are analyzed numerically by comparing the temperature-dependent model with temperature-independent model. The studies indicate the significance of temperature-dependent material properties on the thermal shock fracture and crack growth behavior of solids for high-temperature applications

Magnetostrictive Properties of the Grain-Oriented Silicon Steel Sheet under DC-Biased and Multisinusoidal Magnetizations

As an intrinsic property, elasticity of soft material is affected significantly by the externally applied alternating magnetic field. Magnetostrictive properties of the grain-oriented (GO) silicon steel under DC-biased and multisinusoidal magnetizations are measured by using a laser-based measuring system. Magnetostriction curves of the GO silicon steel sheet under different magnetizations are obtained and the influence of frequency and DC bias on the magnetostrictive property is observed and analyzed based on the measured data. In addition, the spectrum of magnetostriction under harmonic magnetization is obtained, and the acoustic noise level of the GO silicon steel sheet represented by the A-weighted decibel value caused by magnetostriction is measured under DC-biased and multisinusoidal magnetizations. The measurement results are applied to the simulation of the three-limb laminated core model, and the effects of DC bias and harmonics on magnetic flux density and displacement are analyzed

Design, synthesis and cardioprotective effect of a new class of dual-acting agents: Phenolic tetrahydro-Β-carboline RGD peptidomimetic conjugates.

International audienc

Design, synthesis and cardioprotective effect of a new class of dual-acting agents: Phenolic tetrahydro-β-carboline RGD peptidomimetic conjugates

In this study, a new class of phenolic tetrahydro-β-carboline RGD peptidomimetic conjugates was designed and synthesized. The radical scavenging activities of these newly synthesized compounds 12a-c were evaluated in PC12 cell survival assays. The NO scavenging activities of these compounds were confirmed in the acetylcholine-induced vasorelaxation assay. Compounds 12a-c were efficacious in a rat arterial thrombosis model, and were active in ADP- or PAF-induced in vitro platelet aggregation assays, which suggests these compounds also possess anti-thrombotic activity. The beneficial effects of dual-acting agent 12c were demonstrated on the ischemia-reperfusion induced cardiac infarct size and oxidative change in an in vivo rat model. © 2007 Elsevier Ltd. All rights reserved