Advanced Materials Research Vols. 941-944

Abstract: The second remelt is an important influencing factor during semi-solid thixotropy forming technology, and the microstructure is immediately impacted by temperature distribution state. By the way of induction heating the temperature distribution state of 45# steel is researched in this paper. The results indicate: the temperature rises slowly by low power heating and the radial temperature distribution doesn’t reach uniform. But the temperature rises rapidly by high power heating and the radial temperature distribution is nearly homogeneous after a while.

Abstract: Based on pool film boiling, Heat transfer coefficient and cooling model are established when fogdrop jet into cutting zone to cool high temperature wall. Through the transient experiment of cryogenic gas atomization jet cool high temperature nickel-base alloy surface with different water dose. The water dose achieving the best cooling effect is 2 ml/min, 4ml/minand 6ml/min under the nickel-base alloy surface temperature at 300 ℃, 500 ℃and 650 ℃. Then the effect of water density to heat transfer coefficient is discussed. Water dose to the best cooling effect must be equivalent to the amount of water that materials can vaporize and participate in the phase-change heat transfer under certain temperature. When achieving optimal cooling effect, the number of fogdrops participating in phase-change heat transfer are the most , and heat transfer coefficient reaches the maximum.

Abstract: Aiming at the phenomenon that a large amount of friction heat produced during braking process has important influence on the contact surface of heavy vehicle, according to the actual size of the friction plate and the static slice, a three-dimensional transient thermal stress field calculation model has established, using multi-physics coupled method of ANSYS in Workbench, after the numerical simulation of disk brake, the transient thermal stress field distribution has revealed in the process of braking friction piece, the results showed that the stress field and temperature field has a significant influence on each other, indicated that between them there is a clear relationship between the couple.

Abstract: A transient temperature-stress coupled analysis is performed to investigate the thermomechanical coupled analysis of multidisc friction pairs in Hydro-viscous drive under simulated operation conditions. The normal pressure on all the surfaces are obtained from the principle of force equilibrium and then the heat flux acting on the related surface are also deduced. Based on the finite element method, the 3-D transient thermal and thermomechanical models of single pair are established as the typical one. The distribution of thermal and thermomechanical behavior during the soft-start can be studied. The results show that the maximum temperature occurs at the center of each subregion, where hot spots can be observed. The minimum hoop stress distribution can be observed in the separator disk.

Abstract: Based on the situation that universal mill’s roll rings appeared broken roller accident in actual production, the paper put the horizontal roll ring of universal mill as the research subjects. The thermal structure coupling field of horizontal roll ring reaches a dynamic equilibrium and the stress distribution of horizontal roller ring and finds the most dangerous parts of the roller ring is rolling groove. This study provides a solid foundation for further research of the roller ring strength, deformation and fatigue life.

Abstract: Based on the pin-on-ring friction pair jig, the temperature field model was established by FE software ANSYS under the coupled effect of electromagnetic induction heat and friction heat. The coupled temperature field distribution and variation rule of the analysis model were simulated and analyzed under different electromagnetic induction frequency and velocity. The results show that when the rotation angle, stress and electromagnetic induction frequency are constant, the maximum coupled temperature increases linearly with the increment of velocity, and the area of pin temperature gradients narrowed with the increasing velocity; the maximum coupled temperature rises with the increasing electromagnetic induction frequency under the constant rotation angle, stress and velocity. The research will provide FE simulation basis for the controlling of friction and wear by electromagnetic field.

Abstract: The thesis applies the theory of pitch intermiscibility and adopts the orthogonal test to develop the new pitch regenerant through the regression analysis to the test results. Besides, according to the regeneration mechanism, the concentration of the regenerant and the intermiscibility of the regenerant and the pitch also should be taken into consideration.

Abstract: Nowadays, hydraulic fracturing has become the mainly treatment in low permeability reservoirs, but the hydraulic fracturing design technology in different reservoirs still use common methods. Natural fracture reservoirs mainly include granite reservoir, basalt reservoir and igneous rock reservoir which its hydrocarbon pore volume is fracture system. As the existing of natural fracture, hydraulic fracturing treatment always counting some problems, such as difficult sand pumping, easily screen-out and limited scale. In this paper, from the point of the reservoir characteristics, the mainly problems were analyzed and the corresponding methods were put forward .the core technique in this kind reservoir include communicating the distance nature fracture and meanwhile protecting the conductivity nature fracture. Production can reach 90% from natural fractures using numerical simulation.

Abstract: In order to research floor pressure relief law of shallowly buried descending coal-mining working face covered with thin soft bedrock in Dongsheng coalfield , taking Lijiahao coal mine for example, firstly, to calculate the impact depth was 18.86m by the theoretical formula, then analyzing coal and rock mass stress and displacement variation of the upper work surface to its floor during mining based on numerical simulation. Obtaining coal and rock pressure relief depth of the floor was 70m, with the working face advancing, the pressure relief depth and range became larger, to achieve stable at a certain number;affected by the mining of 2-2 coal, coal and rock mass strength of its floor was weak, the largest damage depth was about 18m,this result would provide a basis to the roadway of the 3-1 coal in different coal pitch; affected by the mining, the goaf overburden and floor of 2-2 coal working face appeared "O" shape fracture zone, the floor rock fissure of 2-2 coal got through to the roof of 3-1 coal,cracks formed transfixion,which made the pressure change of 3-1 coal working face, Mine pressure appearance tended to be ease, it would be easily control if the roadway of 3-1 coal was arranged in the area of pressure relief. The theoretical results would be useful to actual production.

Abstract: WuTongZhuang No.182309 mining face is an isolated mining face. The abutment pressure is big and roadway deformation is severe due to driving roadway along goaf with short pillar remained. In view of these problems, taking WuTongZhuang No.182309 mining face as project background, the law of the abutment stress distribution was analyzed by use of numerical simulation software FLAC^3D and field measurement study. The results showed that the influence scope of the lead abutment pressure was about 55m , the peak value was about 6m ahead of the mining face and the stress concentration factor is 3.3.Based on the above study results, a scheme of advanced support was proposed which effectively controlled the roadway deformation and ensured the safety production of the mining face.