Applied Mechanics and Materials Vols. 444-445

Abstract: The mode shape change of tension shear spot welds with propagation of crack was studied. Mode shape would change as crack exists, while the change is not so explicit. Difference between uncracked and cracked model modal shapes showed violent changes, but not give enough information of the crack location. Further Difference between two neighbouring points also can give information of crack, but also not saliently. Combination of the two would give explicit crack location information of the crack for tension shear spot welds.

Abstract: Based on the heat transfer, the prediction model of the direct solar vacuum tube was studied, the concept of local heat loss coefficient was put forward, through the temperature distribution model of metal pipe and fin, the calculation method of average heat loss coefficient was obtained, the calculation accuracy of performance was improved. The results were compared with dates of Abdul Waheed Badar et al, error is less than 7.15%, the calculation accuracy of model meets the requirements. The impact of various factors on the performance of the collector tube was studied.

Abstract: The configuration sizes of multi-layer rectangle micro-channel heat sink are optimized, which has been widely used to cool electronic chip for its high heat transfer coefficient and compact structure. Taking the thermal resistance and the pressure drop as goal functions, a binary-objective optimization model was proposed for the multi-layer rectangle micro-channel heat sink based on Sequential Quadratic Programming (SQP) method. The number of optimized micro-channel in width n₁ and that in height n₂ are 24 and 3, the width of optimized micro-channel W_c and fin W_f are 360 and 55μm, the height of optimized micro-channel H_c is 1000μm, and the corresponding total thermal resistance of the whole micro-channel heat sink is 1.5429 °C/W. The corresponding pressure drop is about 2.3454 Pa. When the velocity of liquid is larger than 0.3 m/s, the effect of change of velocity of liquid on the thermal resistance and pressure drop can be neglected.

Abstract: On the basis of the greedy algorithm, we discuss the classification of the campsites, and a combination of the best rafting program stands out from the many programs. Therefore, in order to meet the full use of the campsites of river and under the premise of reducing encounter times, we make the best planning enable the river to accommodate the largest amount. After statistics, we find that utilization in our model can be achieved as high as 98.5%.

Abstract: In view of the serious problems that low-rate reduction and excessive oil consumption of reducing oil guns which are used in the depleted EAF, analyzing the jet mixing process through the CFD simulation with the method of liquid level tracking, we find that the purpose of mixing slag layer, guaranteeing matte layer precipitation and saving oil can be achieved by changing combination of gas rate of mixture injected by the oil gun, jet speed and insertion depth. The results of this paper provide a theoretical foundation for optimizing reducing technical process of the slag cleaning furnace operation in a copper industry Company.

Abstract: In this paper, by using the result calculated with FORTRAN program based on nonlinear estimation method, the stress field of T10 steel specimen quenching process is solved and analyzed. In order to get an in-depth understanding of the stress field in the specimen, the accurate calculation model and appropriate simplification must be considered. Because T10 steels phase is non-uniform when quenching, in order to get the accurate result, the heat release of phase changing must be considerate.

Abstract: In order to study the response of tungsten under high heat load, the nonlinear thermodynamic equations considering the phase transition were established to the tungsten target irradiated by intense pulsed ion beam. Also the equations which describe the thermal stress and the total strain produced by the changed temperature in the material element were built. Numerical method was used to solve the evolutions of the thermal stress field formed in the target, and spatial temporal evolutions of stress field in the tungsten target are obtained. While the ion current density reached 100A/cm2, the surface materials of tungsten target at the beam incident center was melted and then re-solidified due to the heat conduction after the end of a pulse. There exists the gradient of temperature in tungsten, therefore the thermal stress formed. Radial tensile stress is produced within the melting region, meanwhile outside the region compressive stress is formed; the boundary appears on the edge of the melting region. The stresses on the incidental surface of target are larger compared with the internal.

Abstract: An artificial lake in coastal region was built based on from a sewage reservoir by clearing sediment. Because the high-salinity sediment on the bottom of the Lake and the high-salinity water body around the Lake, salinity of the lake will increase with time. It is necessary to predict and control salinity of the lake. Based on the field investigation on the sediment and water body around the lake, EFDC (environmental fluid dynamic code) was used to simulate the distribution of salinity in the Lake. Simulation shows that more kinds of water sources in different points not only ensure the control of salinity also ensure hydraulic circulation. The results provide the theoretical support for the scheme of supplying water.

Abstract: When using electrometric method to measure the static strain of a structure, the results are often accurate, but the number of measuring points is limited; when using the finite element method to model and analyze the practical structures, there often exist many assumptions of uncertain factors, so the accuracy of simulation results is poor, but the strain values of all the nodes in the grid of simulation structure are available, so the number of measuring points is large. In view of this situation, this paper applied Bayes-Kriging estimation method through the measurement strain data to update the strain on the surface of finite element strain simulation model. We applied the measurement strain data at different stages of the fatigue process to update finite element model. With the comparison of the strain data between before-and after-updating, we can find that at the boundary region and fatigue crack extending direction, the updating result is inaccurate, but the updating effect is good at other position. This method can improve the accuracy of these positions' strain value and make the strain value closer to the actual strain value.

Abstract: For virtue of small volume and fast speed of construction, arch dam is the most suitable dam type in cold region, where construction period is relatively short each year. Low average value and large amplitude of atmospheric temperature make temperature stress distribution of arch affect directly by thickness of permanent insulation material as while as the time of thermal insulation. Extreme climate lead to stricter external insulation requirement for cold region arch than these in common district, however, thermal insulation will increase the burden of artificial cooling and extend the construction period. Therefore, it is complicated and critical for arch dam crack prevention to study on permanent thermal insulation. In view of this, finite element method was applied for simulation of construction processes of a practical project in cold region. Influence of permanent thermal insulation layer thickness and selection of insulation time is analyzed, in order to provide basis for permanent thermal insulation optimization.