Advanced Materials Research Vols. 189-193

Abstract: Taking the high-speed CX series vertical milling compound machining center of CX8075 produced by Anyang Xinsheng Machine Tool Co., Ltd. as example, the machine three-dimensional simplified model is established, the source of the heat and the distribution of the important hot-points are analyzed, the machine temperature field distribution is derived which lays a foundation for the thermal error compensation. Taking into account the moving part-saddle of the machining center, its mathematic model is obtained, the important hot-points are studied, the thermodynamic parameters are determined. Based on ANSYS finite element method, the steady-state temperature field and the thermal deformation of saddle are presented, the optimal design of high-speed and high-accuracy machine tool is doned and its thermal deformation analysis is realized.

Abstract: Special rolling is also called rotary forming process, which is an advanced manufacture technology of making workpiece generate deformation in a rotary state by continuous local plastic forming. Disk rotary parts with outer stepped cross-section, such as wheels, flanges, valves and so on, are widely used in engineering machinery. Traditionally, this kind of part is manufactured by forging and cutting, which consumes a lot of energy and materials especially to the large size part. In this paper, a new specific rolling technique called three rolls cross rolling is first presented to produce this kind of part, and the principle and characteristics of this technique are described in detail. Then, base on the principle of the three rolls cross rolling, a 3D coupled thermo-mechanical FE model is developed under ABAQUS software environment. As a result, under the simulation and analyses of a real example, the feasibility of this technique is verified, and the evolutional laws of the strain, temperature and rolling force and power parameters during the process are investigated as well. The obtained results provide valuable guidelines for the further investigation on the forming characteristic of the three rolls cross rolling technique.

Abstract: Based on standard k-ε model of Fluent, the 3-D numerical simulation of cavitations-impinging stream reactor was studied. The main flow law in the reactor was obtained, and its velocity and pressure fields were analyzed. The results showed that the parameters of the flow field were completely symmetrical by the impinging surface; isobar concentrate in the impinging area which indicated that pressure fluctuations in this region is stronger, it plays an active role on the promotion of flow group micro-mixing. The laws of parameters influence on impinging phenomenon were revealed by analysis the results with different parameters. The basic data and theoretical bases are provided for the optimized and improved design of impinging streams reactor.

Abstract: Partial wheel load is one of the main causes that lead to shear-type reflective crack of asphalt overlay in the old cement concrete pavement. Based on the theory of fracture mechanics and finite element method, this paper focuses on the numerical simulation of the reflective crack propagation path in asphalt overlay under the partial wheel load. Calculation result and analysis show that reflective crack partially expands upwards at the side of wheel load under the effect of partial wheel load with a sequential increase of crack propagation length. As the crack propagation length increases, stress intensity factors grow rapidly in the early period, and then increase by degrees slowly and, in the later period, the amplitude grows increasingly. Stress and strain fields enhance as the reflective crack increases upwards and the crack propagation angle expands gradually with the increase of reflective crack propagation length.

Abstract: The rockwool has excellent thermal insulation performance, makes the hull structure and high-temperature asphalt effective isolation. But asphalt carrier’s temperature stress field distribution will be impacted once the rockwool damaged, so the rockwool damage factors are interested. The finite element model of cargo hold and rockwool are created in the present paper, the temperature stress field distribution is concerned with different boundary conditions and material properties.

Abstract: Numerical study established by using ANSYS 12.0 has been performed by considering convective and radiative heat transfer to predict the transient thermal behavior of a brake disc during air-cooling process of heat treatment. Though the model based on the numerical study, temperature distribution maps at different time delays and variation in the temperature at different parts of the brake disc are given. Additionally, experimental results demonstrate the validity of the simulation analysis through comparing with the results obtained from the transient analysis. It is shown that the air-cooling numerical model of brake disc is verified and has the rather accurately temperature prediction ability.

Abstract: Ground anchors are common to be employed in geotechnical engineering. Under a limited space of an urban district or a restricted thick of an anchored stratum, an under-reamed anchor could meet both the requirements of a short length and a high anchorage capacity. To investigate the anchorage mechanism of the anchor, a series of triaxial tests was performed to obtain the parameters demanded for a constitutive model, SHASOVOD (A continuous strain hardening/ softening and volume dilatancy model for cohesionless soil during stressing). A numerical program was then developed to study the uplift behavior of the under-reamed anchor in silty sand. Analyzing results show that, for two under-reamed anchors located in different test sites, the complete load-displacement curves estimated numerically were consisted with those measured from the field test. The total load, friction load and end bearing do not reach their peaks simultaneously. According to the behavior of the end bearing, a critical overburden depth H of 6D was found to classify an under-reamed anchor as a shallow anchor or a deep anchor.

Abstract: Drive axle is a key part of transmission system on the articulated vehicle. Its stability has a great influence on the performance of the truck. The gear transmission system of 45t articulated vehicle drive axle is taken as an example while the virtual prototype models of drive axle gear transmission system are established with Romax. The comparative simulation analysis of fatigue life of drive axle supporting bearing is performed through two means, the ISO281 and Romax Adjusted, which are methods for predicting bearing fatigue life. The results of simulation show that each supporting bearing has long life, low wear rate and long working time; the prediction of bearing fatigue life with Romax Adjusted agree with the actual work condition of bearing.

Abstract: This paper deals with the issues involved during the design of a complex roof structure in the grand theater located at the city of Hangzhou, China. The complexity comes from the structural being of three reasons: long-span, complex structure and special figuration. To study the roof structure completely, researches on the mechanical properties of the structure are carried out in the paper. The nonlinear finite element method is used to analyze the geometrical nonlinear stability. Buckling and post-buckling analyses are performed to determine the load-carrying capacity of the perfect and imperfect roof structure. Meanwhile, the critical loads of the structure with different parameters are also discussed in this paper. It is shown that the effect of supporting stiffness originated from foundations and concrete structures to improve the critical load is evident. The buckling of the structure is a global collapse. With the temperature rises, the limited load-carrying capacity of the structure decreases obviously.

Abstract: Taking Silicon tetrachloride (SiCl4) and hydrogen (H2) as the reaction gas, by the method of plasma-enhanced chemical vapor deposition (PECVD), this paper simulates the deposition process of polycrystalline silicon thin film on the glass substrates in the software FLUENT. Three dimensional physical model and mathematics model of the simulated area are established. The reaction mechanism including main reaction equation and several side equations is given during the simulation process. The simulation results predict the velocity field, temperature distribution, and concentration profiles in the PECVD reactor. The simulation results show that the deposition rate of silicon distribution is even along the circumference direction, and gradually reduced along the radius direction. The deposition rate is about 0.005kg/(m2•s) at the center. The simulated result is basically consistent with the practical one. It means that numerical simulation method to predict deposition process is feasible and the results are reliable in PECVD system.