Advanced Materials Research Vol. 664

Abstract: Laser cutting of materials is becoming the preferred method of cutting. It has many advantages over conventional machining techniques such as better quality of cuts, quick and accurate cutting. The objective of this work is to investigate the effect of the main input laser cutting parameters, laser power and cutting speed, on the microhardness of stainless steel sheets obtained by CO2 laser cutting. The experimental tests were performed at various laser powers and cutting speeds. The cut surface was studied based on microhardness depth profiles beneath the machined surface. In order to investigate the metallurgical alterations beneath the cut surface, the microstructure was observed by using scanning electron microscopy. The results show that the microhardness and the surface microstructure are affected by laser cutting. Laser cutting leads to the formation of periodic striations and cracks. Also the main parameters of cutting, laser power and cutting speed, have an effect on surface microstructure and microhardness.

Abstract: This article using the method of orthogonal test analysis the law of honeycomb ring part in aero-engineer surface discharge mark diameter by EDG. In the impulse voltage under certain conditions,by changing the peak current and pulse width in the interelectrode study both of the impact of the largest diameter of GH3536 surface discharge mark, and build a mathematical model of the regression equation, derive relatively accurate empirical formula. Provide a good reference and guidance for the actual production of the EDG.

Abstract: Reissner’s plate bending fracture theory with consideration of transverse shear deformation effects is adopted for the crack problem of power-law functionally graded materials (FGMs) plates. Assume that the crack is parallel to the material property gradient. By applying the asymptotic expansion method, the crack-tip higher order asymptotic fields which are similar to Williams’ solutions of homogeneous materials are obtained.

Abstract: In order to research welding technology of DX51D+Z cold rolled galvanized steel, using multivariate nonlinear regression orthogonal combination design method, adopted the shear load as quality indicators, counted welding current, electrode force, welding time, squeeze time and the interaction of them as factors, to built the nonlinear regression models, by adopting this model to forecast shearing load. The result shows that this model has high forecast precision.

Abstract: The surface finish of fused deposition modeling (FDM) processed part is excessively rough due to stair stepping effect. In addition, the tensile strength of rapid tooling fabricated by FDM is inferior to that fabricated by plastic injection molding. A hybrid rapid tooling technology is developed to improve the surface roughness and increase the tensile strength of rapid tooling fabricated by FDM using epoxy-based composite in this work. Improvement rate of tensile strength of rapid tooling is 2.34 times of the add rate of epoxy-based composite. Surface roughness improvement rate of up to 92.94% can be achieved. Hybrid rapid tooling technology owns low manufacturing cost, simple manufacturing process and good flexibility.

Abstract: Silicone rubber mold is regarded as an important method of reducing the cost and time to market in a new product development process. Commercial automatic vacuum machine is widely used to degas in the manufacturing of silicone rubber mold, but the cost of hardware is very expensive. A high efficiency degassing system is designed and implemented from regular vacuum machine. It is found that degassing process includes explosion phase, balance phase and convergence phase. The maximum saving in the degassing time is about 63.7%. The advantages of this system include reducing human error of operator, reducing noise and air pollutions derived from the vacuum pump.

Abstract: The physical weak-discontinuous problem of an interfacial crack between homogeneous material and functionally graded materials (FGMs) is studied based on Reissner’s plates considering transverse shear deformation effect. The crack-tip higher order asymptotic fields of homogeneous materials and FGMs regions are obtained by the asymptotic expansion method, respectively. Finally, the whole crack tip high order fields are assembled and given. The results provide a theoretical basis for solving interfacial crack problems of FGMs plates and their engineering application.

Abstract: Quantity determination of the Aircraft spares is affected by many factors, the indeterminate effect is not quantitative factors on the quantity of spare parts, analytic hierarchy process is applied to the quantity calculation of the aircraft spares. General principles of administrative levels to analyze law dealing with the aircraft spares calculation of multi factor problem is introduced, 5 influence factors is economy, importance, difficulty degree, affected, string etc. The use of analytic hierarchy process used in random spare parts calculation is illustrated.

Abstract: Thermoforming machine plays a very important role in industrial production, food packaging and other industries. In traditional thermoforming machine, highest temperature often appears in the center of the heating zone, and gradually reduces from the middle to both sides. It results in uneven heating, reducing the rate of finished products and a waste of resources. According to the finite element method, this article established the thermal field model of matrix heating system in thermoforming machine and simulated the temperature distribution of plastic in heating system under the conditions of “uniform heating” and “non-uniform heating” separately. It found that under the condition of “non-uniform heating”, the temperature distribution appeared uniform. The temperature of main region to be heated appeared approximately linear distribution, with the variation range of less than 5 °C, resulted in better effect than that under the condition of “uniform heating”

Abstract: The study of boundary layer flow and heat transfer near a rotating disk with nanofluids is investigated numerically. Three types of nanoparticles, namely, silver Ag, copper Cu and alumina Al₂O₃ with water as the base fluid are considered. The results show that the momentum boundary layer thicknesses shortens as the nanoparticle volume fraction increases, whereas thermal boundary layer thickness elongates for increasing ϕ. It is found that the reduced skin-friction coefficients and heat transfer rateat the rotating surface increase linearly with nanoparticle volume fractionϕ. The surface heat transfer rate for Cu-water nanofluid is higher than those of the otherswhen ϕ>0.02, even though the nanoparticle Ag has higher thermal conductivity than that of copper Cu.