Applied Mechanics and Materials Vols. 268-270

Abstract: The microstructures of the aluminum billets could be improved markedly by low-frequency electro-magnetic casting (LFEC) processing. In fact, the low-frequency electromagnetic field (LFEF) also has favorite effect on the surface quality of billet. However, few public reports on the surface quality of LFEC aluminum billets could be found. Therefore, a new crystallizer together with a kind of lubricant was designed aiming at lowing surface turning quantity, and the effects of casting velocity, electromagnetic condition and lubrication on the surface quality of aluminum billets were investigated. The results indicate that LFEF together with the lubricate condition would be responsible for the surface quality of the billets, and the high surface quality billets could be achieved by optimizing the casting conditions.

Abstract: Based on the femtosecond laser processing technology and PZT driving scanning technology,high-precision micro- manufacturing technology is developed. By adjusting the laser parameters and scanning parameters to get micro-hole machining on the flat or curved surface. Hole’s size and surface morphology is observed by using phase contrast microscopy and scanning electron microscopy observations, and the surface roughness is analyzed by the surface profile instrument. The feasibility of diesel injector nozzle processing is verified in practical industry applications. The results show that this method of making micro hole has significant advantages, such as high precision, good consistency, without burrs, good surface roughness and high efficiency. These characteristics can meet the practical application requirements and can be used in various industrial fields.

Abstract: To consider the high energy consumption and the key components are easy to damage in CZ crystal furnace, in this paper, a multi-field coupled analysis on temperature and flow field has been carried out by using FEM software ANSYS, and the APDL language of ANSYS is used to implement the parametric model design for CZ crystal furnace. In addition, the abilities of APDL to make dynamic model modification, control calculation procedure and extract the result are exploited to simulate the preparation process of CZ crystal and get the temperature and flow field. The results can be used for guiding the producing process of CZ crystal.

Abstract: Extrusions of a 6061 aluminum rectangular tube using porthole dies with three assigned different split ratios were simulated by the software DEFORM-3D based on Finite element method. The distributions of stress, equivalent strain rate, temperature, velocity of the deformation materials and the mold stress during the three extrusion processes were obtained, respectively. By analyzing the distributions of those fields, the most reasonable split ratio is selected and then the die structure is modified.

Abstract: To explore a way to characterize fatigue damage degree of ferromagnetic materials by metal magnetic memory testing (MMMT), tension-compression fatigue test of specimens with different stress concentration factors made of 45% C steel were carried out. Both normal and tangential component of magnetic memory signals, Hp(y) and Hp(x), of specimens under different fatigue cycles were measured by EMS-2003 and RM-1 magnetic memory testing apparatus respectively. The results show that, the gradient variation of Hp(y) signals during the fatigue test is similar to each other, but the gradient value is different due to the different stress concentration factors. And so is the relative peak value of Hp(x) signals. Both gradient of Hp(y) and relative peak value of Hp(x) can be used to distinguish the stress concentration degree of specimens.

Abstract: In order to obtain the optimal technological conditions of preparing biodiesel, artificial neural network was used to study the biodiesel processing model on transesterification method based on the single factor experiment and orthogonal experiment. The results of experiment indicated that we used the back propagation BP algorithm of artificial neural network to set the network prediction model based on the orthogonal test data can forecast the biodiesel conversion rate under different reaction conditions more accurately.The optimal conditions were obtained from this network model as follows: Molar ratio of methanol to oil was 6:1, the catalyst was 1.0% (w/w, based on oil), reaction temperature and reaction time was 65°Cand 2.5h respectively. Under the optimal conditions, the prediction conversion rate was 96.019%, the testing conversion rate was 96.83% and the relative error was 0.84% compared with predicted value. Therefore, the network model could reflect the inherent law of sample.

Abstract: In order to investigate the persistence and stability of the human hair setting effect, different setting temperature, setting time, dry and damp conditions were designed to carry out damp-heat setting on real hair samples. Crimp recovery was used to evaluate elastic recovery of crimp hair. The tensile properties of human hair before and after setting were also tested. Results showed that crimp hair setted in the damp state presented a better elasticity than that in the dry state. With the increase of setting time, crimp elasticity increased. In the damp state, setting temperature of 114°C and setting time of 40 minutes were the best condition for the setting of crimp hair.

Abstract: The machine of friction material on mixing and granulation was prepared. In this text, it is showed the working principle、structure parameter and composing parts and means of the machine. It has the character of the inexpensiveness、compactness、sensitivity、safety and convenience、adjustable angle、mixing uniformity and efficiently. With the application of the friction material for disposing, the research will be done from the material to structure.

Abstract: The liquid/solid composite technology has wide range of applications in the preparation of Fe-Al composite materials and structures. The diffusion-reaction zone (DRZ) formed in the liquid/solid interface has a great influence on their properties. The Al-Fe diffusion couple was prepared by using the insert technology and treated at 700°C-900°C. The microstructure evolution and growth mechanism of the DRZ in the Al/Fe liquid /solid interface were investigated. The result shows that the microstructure of Al/Fe liquid/solid diffusion couple after heat treatment (HT) is (Al+FeAl3)/FeAl3/Fe2Al5/Fe; Fe2Al5 is the only new phase during the heat preservation process, FeAl3 is formed by desolventizing during the cooling process. The growth of the Fe2Al5 is controlled by the chemical reaction of the Al atoms and Fe atoms before the Fe2Al5 continuous single-phase layer is formed; Once the continuous Fe2Al5 single-phase layer is formed, the growth of the Fe2Al5 mainly depends on the diffusion of Al atoms in the solid phase Fe2Al5 layer, and the reaction occurs in the solid/solid interface of the Fe2Al5 layer and iron. Precipitate is not found in the iron while the needlelike and strip FeAl3 precipitates appear in the aluminum; the density and size of the FeAl3 precipitates decrease gradually from the vicinity of interface to the distant.

Abstract: The application of Finite Element Method (FEM) in cutting force model for Aluminium alloy work-piece is useful to reduce the production costs and shorten the experimental period. Firstly, the theoretical model of the orthogonal cutting and the oblique cutting are analyzed in this paper. And then, the corresponding finite element models are theoretically constructed. By comparing the results, the following conclusions are drawn: with the increase of the cutting thickness, the cutting force increasing is in an enhancement tendency. The oblique cutting model of overall tool is more conductive to the subsequent runout and the flutter analysis.