Advanced Materials Research Vols. 148-149

Abstract: Started from a widely used FK model of Reynolds equation, a new simplified model, called continuous FK (CFK) model, is proposed to simulate the ultra-thin air bearing film in hard disk drives (HDDs). The new model of Reynolds equation possesses simpler mathematical form than that of FK model. The new model is solved by using a least square finite difference (LSFD) method and the resultant numerical results are compared with those of FK model. It is found that numerical results of the two models are in very good agreement.

Abstract: Aim: presents a stress correction method to improve calculation accuracy of doubly curved composite laminated plate with big meshing size to save computational effort. With the application of Marc’s secondary development function, a subroutine is embedded to simulate the mechanical properties of material, and the amendment factors are added so that the stress calculation results have the same computational accuracy when the model is compartmentalized to big meshes as the case under small meshes. We Compare the calculation results in big meshes and what in small meshes, which prove the error request can be satisfied.

Abstract: Machining error of vibration beam rate sensor and its influencing to the performance of solid vibration inertial sensor were studied. The dynamics model was analyzed, and the mechanism error caused by the technology limit was studied and the theory of deducing the error was presented. Numerical calculations combined with 100mm alloyed vibration beam have been made. Results showed that quadrature error is the primary factor of affecting gyro’s performance; the error caused by mass center deviation of vibration beam change with angular acceleration, which can be ignored under the condition that small angular acceleration. The affects of parasitic Coriolis error on performance is minimal, which can be neglected. Finally, the quadrature error’s simulation results were consistent with expected results. The result also proved that restraining and compensating quadrature errors is one of the key technology to increase the performance.

Abstract: The dynamic characteristics of the pavement plate on the elastic foundation were investigated. Based on semi-analytic element method and variational principle, the dynamic equations of the pavement plate on the elastic foundation were deduced. Through the analysis and calculation, dynamic response of pavement plate placed on the elastic foundation with vertical load was calculated by the semi-analytic element method. The deflection time histories curve of the plate under load on the elastic foundation was given. The effects of foundation parameters and the plate parameters are examined through numerical examples. The results show that the deflection of the pavement plate decrease with the increasing of thickness and elastic module of pavement plate, in the same time, the deflection of the plate is decreasing with the increase of the damping coefficient and elastic modules of foundation. Those parameters have significant effects on the deflection of the pavement plate.

Abstract: In this study, the influence of pulling velocity on temperature field, fluid field and grain structure of a unidirectionally solidified superalloy DZ417G cylindrical casting was investigated by using a 3D cellular automaton finite element (CAFE) model within commercial software CALCOSOFT. The predictions show that temperature distribution in the casting is well in accordance with the experiment result. The solidification front and fluid field are sensitive to changes in pulling velocity. And the pulling velocity should be controlled less than 0.5 mm/s in our experiment so as to effectively decrease the grain number and mean grain deviation.

Abstract: Basing on the coupled vibration theory, dynamic behavior of steel bridge deck thin surfacing under rand moving vehicles is studied. A three-dimensional coupled model is carried out for the steel bridges deck thin surfacing and vehicle. A method based on modal superposition and state space technique is developed to solve dynamic response generated by vehicle-surfacing interaction. The dynamic responses of an actual steel bridge deck thin surfacing are studied. The results show that adding epoxy asphalt as a sub coat can improve interface adhesion strength, which would be designed as the interface layer of steel deck thin surfacing.

Abstract: This paper focused on the sustainable development of advanced manufacturing technology, discussed the information technology, new materials technology and biotechnology on the enormous supporting of advanced manufacturing technology, and their important roles were pointed out. The information technology was the soul of advanced manufacturing technology, and many advanced manufacturing modes were based on information technology. New material technology was the key to the further development of advanced manufacturing technology, and it was the basis of the actual application of advanced manufacturing technology. Biotechnology provided new manufacturing models and methods for advanced manufacturing technology, so that advanced manufacturing technology had made encouraging progress, and as a result, the bio-manufacturing engineering was a kind of advanced manufacturing mode and the bionic design was a kind of advanced design method based on biotechnology.

Abstract: The correlation among heat input (HI), microstructure and properties in heat affected zone of ASTM A572 GR.65 steel (GR.65 steel) was investigated using optical microscopy (OM), Vickers hardness tester and Charpy-V-Notch (CVN) testing. The result shows that due to the restriction by the Nb(CN) precipitates, the grain size in coarse grain heat affected zone (CGHAZ) at a heat input of 10 kJ/cm is 75 µm, which is half as that at the heat input of 40 kJ/cm. It is indicated that weld preheating is beneficial to the toughness in CGHAZ at low heat input of 10 kJ/cm, while it appears the opposite effect at high heat input of 40 kJ/cm. The heat input has a great influence on dissolution of precipitated particles and the austenite grain size, which contributes a lot to the microstructure and properties of GR.65 steel.

Abstract: Aimed at few reflections on the scenario characteristics in the most methods of LCA, this paper presents a new approach taking specific information of scenario into account in the environmental impact of product. By analyzing the relation between scenario and environmental impact, the attributes of space, time and person are extracted as the most basic characteristics. In order to avoid the deficient of science modeling between the scenario attributes and the environmental impact processes and to use conveniently, the concept of scenario characteristic coefficient is proposed and the three types of coefficients are expressed in detail applying the existing data or statistic. The method of LCIA considering scenario characteristics is presented by integrating the characteristic coefficients into the LCI processes. And this method is applied to study the scenario characteristics of an LCA of electromotor.

Abstract: In continuous tube rolling process, it has an obvious influence on the stability of rolling process, tools wear and the quality of rolled hollow tube that configuration of roll rotational speed per stand. In this paper, various roll working diameters per stand are determined by velocity integral method (VIT) and FEM respectively, and two roll rotational speed schedules are obtained correspondingly based on 133 main pass sequence of 89mm 6-stand semi-floating mandrel mill. With the aid of commercial FE code MSC.SuperForm, the high pressure boiler steel tube continuous rolling process of a typical hollow tube specification 133.0×5.2mm are simulated, and force parameters, transverse wall thickness precision, outline dimension and real roundness of rolled hollow tube and clearance between the mandrel and rolled hollow tube are analyzed and compared on the condition of two different roll rotational speed schedules, which provides scientific basis for configuring reasonable roll rotational speed per stand in pass design and optimization. Analysis results indicate that roll working diameter obtained per stand is smaller and roll rotational speed configured is higher correspondingly using FEM compared to VIT. Using FEM, there exist front and back tensions between stands and maximal rolling force, rolling moment and mandrel axial force decrease 10% or so in continuous tube rolling process, and outline dimension and real roundness of rolled hollow tube is better. However, transverse wall thickness of rolled hollow tube at the bottom of groove is pulled thin slightly, and clearance between the mandrel and rolled hollow tube is less than normal.