Advanced Materials Research Vols. 557-559

Abstract: Computational fluid dynamics (CFD) method was applied to the study of flow field in the agitation of glycerin fluid with a Rushton impeller and a pitch 4-bladed turbine. The flow was modeled as laminar and a multiple reference frame (MRF) approach was used to solve the discretized equations of motion. The velocity profiles predicted by the simulation with four different impellers rotating at constant speed of 200r/min were obtained. By analysis to their axial, radial and tangent velocity vector plots, velocity contours and velocity distribution curves, it was found that the stirred effect of the Rushton impeller was better than one of the pitch 4-bladed turbines，however，accompanied with high power consumption according to the calculated values of required power. Moreover, there were all similar flow characteristics for the pitch 4-bladed turbines with different blade pitch angle. The research provided a theoretical basis for the design and practical application of the stirred tank under laminar flow.

Abstract: At present, the studies of bubble crystallization focus on the gas velocity, crystallization efficiency and crystallization yield, the effects of other factors were not considered. So it is very important to study factors comprehensively that effect on the gas-liquid two-phase flow of bubble crystallization. In this paper, Fluent was used as a computing platform and RNG k-ε turbulence model and VOF multi-phase model was selected to simulate gas-liquid two-phase flow of bubble crystallization. The results show that as the gas inlet velocity increases, slug bubbles are more and more bigger, more and more dispersed bubbles are below the slug bubbles, crystallization efficiency first increases and then decreases; Under the gas pulse-inlet form condition, the better operating parameters are: gas velocity 1.0m/s, pulse duration 0.4s, interval time 0.8s, crystallization tube diameter 40mm. Simulations agree well with experimental data.

Abstract: The thermal conductivity of porous material is an important basic parameter, but it is not easy to study, due to the complexity of the structure of porous material. In the present work, we show a numerical simulation method to study the thermal conductivity of the porous material. We generate 200 material models with random distribution of solid skeleton and air for a fixed porosity, then we get the effective thermal conductivity of the porous material by Monte Carlo statistical analysis. The results are in good agreement with the previous empirical formula. The numerical results show that the effective thermal conductivity of porous material depends on the thermophysical properties of solid skeleton and air, the pore distribution and pore structure, the numerical error decreases with the increase in the number of grids, this finite element method can be used to estimate the effective thermal conductivity of composites and maybe has broad application prospects in terms of computing the effective thermal conductivity and other physical properties of composite material with known components.

Abstract: We report simulations of multilayer epitaxial growth using a previously proposed continuum phase field model [2, 5]. For island growth in the multilayer regime, this phase-field model reproduces mound structures consistent with experimental images concerned. We focus on the evolution of morphology on multilayer islands under a certain condition. Roughness of epitaxial surface increases rapidly with the coverage increasing when the deposition rate is larger than a critical value. Layer-by- layer growth is the most primary method among the styles of islands growth under low deposition rate. Roughness is independent of temperature, when the temperature is larger than a critical value.

Abstract: Chemical explosion may occur in urea reactor. The explosion load and the dynamic response of the multilayer structure are analyzed. Based on Russel model, the maximum explosion loads were calculated by thermodynamic methods. Dynamic response was simulated by Ls-dyna software. The result shows that the explosion pressure is smaller than the burst pressure; the stress distribution along the radial direction and the effective stress history are obtained and they both show some new features. The results may offer some reference significance for similar structure strength design and safe protection.

Abstract: In order to describe the effect of shear stress on the sidewall rock mechanic distribution accurately, in this paper, we have established the micro unit stress equilibrium equation for failure zone and damage zone of the sidewall rock based on damage mechanical mechanism. Establishing the model for calculating radial stress, circumferential stress and shear stress of the sidewall rock considering the shear stress. We have obtained the scope of failure zone and damage zone of the sidewall rock by using central difference method. The result shows that the calculated result considering the shear stress is fit to the actual one

Abstract: This paper investigates the fatigue life prediction and fatigue life enhancement of connecting rods of car engine. The fatigue life prediction was simulated by analyzing the stress occur in the connecting rod and then simulate the fatigue life prediction. The stress analysis was done by using finite element method. The results obtained from stress analysis is used as the input to simulate the fatigue life using stress-life method. The simulation was done for two models, the existing model and modified model. The modified model is the existing model with increased thickness in the highest stress region. The results show that the modified model has an improved fatigue life up to 231% compared to that of the existing model.

Abstract: In the automotive industry, the hot forming of high strength steels offers the possibility to obtain significant reduction of weight without affecting the structural performances of final products. Compared with conventional sheet metal forming, the proper design of hot stamping process chain requires the deep knowledge of both interface phenomena and material behavior at high temperatures in order to obtain the desired properties of final products in terms of microstructure and strength characteristics. The work presented in this paper aims at accurately evaluate the effect of heating parameters on the properties of final sheet components produced in hot forming operations. Different from that in the lab, all the samples and parts used for the experimental test were produced in the production line, which can objectively show the manufacturing properties and microstructure character of products in mass. Microstructure evaluation, hardness measurement and dimensional accuracy test after hot stamping were performed and considered. The best heating parameters for the researched hot stamping B-Pillar’s production were obtained through the above research.

Abstract: Cellular manufacturing (CM) is a production approach directed towards reducing costs, as well as increasing system's flexibility in today's small-to-medium lot production environment. Many structural and operational issues should be considered for a successful CM design and implementation; such as cell formation (CF), production planning, group layout (GL), resource allocation and scheduling. Most researchers have addressed these issues sequentially or independently, instead of jointly optimizing a combination of these issues. In order to attain better results to ensure that the system will be capable of remaining efficient in unknown future situations, these issues should be addressed simultaneously. In this paper possibility of developing a comprehensive mathematical model which considers these issues is discussed.

Abstract: In recent years, along with spiritual civilization and material civilization as well as the diversified development of design methods, people are urged to have higher demands on aesthetic standard, consumption concept, values and so on. Packaging design has therewith become protean, already broken through from simply protecting goods in the early days, into an extrinsic form of commodity competition. Material is the substantial carrier of packaging. No matter how novel the design originality is and how beautiful the design graph is, it must be realized relying on material. However, many companies or designers overemphasize on luxurious packaging. Not only do the raw materials cost high, they are also hard to recycle, which would eventually bring about influence to our living environment. Therefore, the application of green packaging material is of great urgency.