Advanced Materials Research Vols. 129-131

Abstract: An ultrafine microduplex structure was successfully produced through equal channel angular pressing (ECAP) at ambient temperature. According to the morphological characteristics of cementite lamellas, the deformed pearlite consists of shear break lamella, locally thinned lamella and irregularly bent lamella. The proportion of locally thinned lamella and irregularly bent lamella has increased with the pass number of ECAP. In addition, the deformed pearlitic ferrite became a supersaturated solid solution of carbon due to the partial dissolution of cementite during ECAP.

Abstract: Waterborne preservative of DDAC and boride are used to impregnate P. ussuriensis Kom lumbers by roller compression under compression rates ranging from 10 percent to 50 percent. Results showed that the cranny in intervascular pit membranes appeared, and the cell wall of vessel element and fiber segment displayed drape and cranny due to roller compression. With the rise of compression rate, both the penetration depth of preservative and the retention quantity of preservative in the experimental lumber increased, while the mass loss rate decreased.The penetration depth perpendicular to the grain was more than 3.9 mm, while that parallel to the grain of wood was more than 20 mm when the compression rate was greater than or equal to 30 percent. Under the compression rate of 30 percent, the retention quantity of preservative in the experimental lumber impregnated with DDAC (thickness of 1 percent) was 8.743 kg/m3 and the mass loss rate was 14.36 percent, while those with boride (thickness of 2 percent) are 3.322kg/m3 and 9.92 percent.

Abstract: During the drilling of stacked materials, burrs forming on both the surface layer and the interlayer have some undesirable characters with regard to assembly quality, and deburring is a time-consuming and costly operation. This paper presented an experimental study on dry drilling of Ti-6Al-4V titanium alloy and 7075-T6 aluminium alloy stacked materials, which was performed by using uncoated cemented carbide drills. The burr size was evaluated at various spindle speeds, feed rates, stacking sequence and clamp force. Finally, the burr morphology was observed and analyzed. The best process parameters recorded in this paper were at the spindle speed of 2000r/min, the feed rate of 0.075mm/r, the pressure of 0.3MPa and the stacking sequence of the Ti-6Al-4V titanium alloy on top of the 7075-T6 aluminium alloy.

Abstract: In this study, alkali preimpregnation was proved to be an pretreatment that could remove the hemicellulose effectively. Both the concentration of NaOH and the preimpregnation time were investigated. The optimum amount of NaOH was 16% od wood in the kraft pulping process. Cooking with 0.05% AQ (anthraquinone) could avoid the reduce of cellulose. The physicochemical Parameters of acetate grade pulp can be achieved after the O-D-E-D-E-Q-P-A bleaching sequence.

Abstract: According to the structure of workbench and base of heavy hydrostatic bearing which is applied in heavy equipment, thermal deformation equations of the structure are deduced and boundary conditions for numerical simulation are established based on thermal elasticity theory. Then thermal deformation of hydrostatic bearing without load is calculated at different velocity. The results indicate that: temperature and velocity impacts a significant influence on thermal deformation of hydrostatic bearing. Thermal deformation increases as the velocity increases; workbench up-warps severely, oil-pad inclines towards outside to a certain extent, which results in the lubrication clearance emerges as wedge-shape deformation. The conclusions from thermal deformation calculation could provide theoretical basis for structure design of hydrostatic bearing and ravel out the thermal deformation problem.

Abstract: In view of the defect and shortage in cutting path automatic optimization of 2D pattern pieces in current garment automatic cutter, a new optimization method of computer is explored. If there is no cutting path optimization implemented by garment automatic cutter before cutting, some problems will be caused, such as too much unless travel and too long processing time. At present, both at home and abroad, the studies on automatic optimization in cutting preprocessing are relatively weak. According to the “segment cutting from left to right” feature of automatic cutter in cutting process, an algorithm which can be summarized as “segment and reducing point” was proposed. This algorithm combined with the solution of shortest path problem, its purpose is to seek for the approximate optimal solution of cutting path. The algorithm implemented through Visual C++ 6.0 programming. Used in production by enterprise shows that the program is simple to operate, and has a high compute speed. Averagely, unless travel in cutting process reduced more than 10%. It proves that the algorithm is feasible and efficient. Using this algorithm achieved the purpose of reducing unless travel, improving cutting efficiency and lowering the cost.

Abstract: The external curing method is usually adopted as the traditional molding process of thermoset fiber composite shell, which places the wound shell into the thermal compression reactor or the oven to cure. This kind of process greatly limits the molding efficiency because winding and curing proceed respectively and separately. The internal curing can be adopted because of the hollow structure of the cylinder-shaped shell, which heats the mandrel with high pressure steam to realize the in-situ curing of the wound shell. This paper researches the new fiber composite molding process named heated mandrel winding. Not only does the heated mandrel winding inherit the advantages of internal curing process, it also greatly improves molding efficiency and quality. This paper introduces the process principle of heated mandrel winding and uses the finite element analysis software FLUENT to carry out the numerical simulation of steam flow and heat transfer during the mandrel heating process, and the simulation results are verified by experiment. According to the simulation results, the distribution and changing course of the flow field and temperature field of the system are obtained, and the relationships between the physical quantities including pressure, temperature and velocity and the parameters of the steam control and channel structure are analyzed.

Abstract: The yield line analysis method is adopted to develop expressions for predicting yield load of bolted I-section web as the connecting face governs the failure of such connection. The proposed expressions are studied by varying the ratio, , of the bolt gauge width to the effective width of the web. By introduction of connecting face deformation limit, the comparison of the yield loads predicted by theoretical expressions and finite element analysis are demonstrated a satisfactory result for practical design. Thus, the yield load predicted by proposed expressions can be used as the basis for design of the bolted connections to I-section webs.

Abstract: In this paper, dynamic properties of EMC were studied at different temperatures and different strain rates. Firstly EMC was investigated by quasi-static tests. Secondly a series of dynamic compressive experiments of EMC were conducted using the Split Hopkinson Pressure Bar (SHPB) at sectional height of strain rates. Thirdly EMC constants in ZWT model were determined from experiments. Corresponding measurements were conducted at temperatures ranging from 20°C to 160°C. The results indicate that the yield strength and flow stress of EMC increase remarkably with the increase of strain rate and it is shows that the assembled curve is fit good accordance with actual the experimental curve. However, the yield strength of EMC is a little change with the increase of temperature which is ranging from 20°C to 160°C.