Advanced Materials Research Vols. 308-310

Abstract: The problem facing of spool used in high pressure wellhead is illustrated. The methods and steps of conventional design and autofrettage design for spool are introduced. Based on the 4rd strength theory, the wall thickness of spool under 103.5MPa is designed using the two methods. Compared with the conventional design, the wall thickness of spool is declined 16.6%, the gross weight is 60% of previous, the stress distribution is more uniform and the utilization rate of raw materials is increased by autofrettage. Thus it provides a theoretical basis for design of spool used in high pressure wellhead.

Abstract: By numerical simulation computation, after passing the pulsating flow, enhanced heat transfer mechanism in spirally fluted tubes was researched. Numerical result shows that pulsating flow can cause the outlet pressure to fluctuate cyclical and the extent of fluctuation increases with the pulsating flow frequency. The pulse flowing can make the fluid generate the whirlpool nearby the spirally fluted tubes and the phenomenon of periodic production, drift, and fall-off appears. Because of the vortex, the fluid motion and relative motion are enhanced. The pulse flowing can improve the coordination level between velocity and temperature, thus has strengthened the heat transfer effect.

Abstract: With the scenario of reliability estimation, a geometrically complex mechanical/structural component with multiple damage sites should be treated as a system, since there are many links (damage sites) of similar failure probabilities on any of such a component and the failures of the individual damage sites are not perfectly dependent of each other. Conventional system reliability model is not applicable to such a system because of the statistical dependence among the element (damage site) failures. To estimate the reliability of a mechanical system (or a complex component) in which element (damage site) failure dependence plays an important role, a model capable of reflecting the effect of element failure dependence is necessary. The present paper develops models which can deal with multiple damage sites and multiple failure mechanisms, reflect the dependence among element failure events and that among different failure modes. Such models are applicable to both typical mechanical systems and various components.

Abstract: Based on the cavity expansion theory, an analysis model of normal penetration of slender nose projectile into armor targets was established, and the variation relation curve of penetration depth and initial velocity when initial velocity is below ballistic limit was obtained. By carrying out ballistic impact test using 85mm smoothbore gun, various projectile nose shapes and armor target thickness and their effect on damage were considered. The research results have indicated that the damage of target is mainly ductile reaming and the shape of crater is almost the same as the projectile nose embedded in the target. Within a relatively low velocity range, nose shape has a greater influence on penetration depth. In contrast, within a relatively high velocity range, the target thickness has a greater influence on penetration depth. It can provide theoretical basis for the design of projectile noses and analysis of anti-penetration performance of armor targets.

Abstract: This paper describes the design and manufacture of a Miniature Unmanned Aerial Vehicle (MUAV) using the StratasysTM 3D Rapid Prototyping (RP) machine. The main motivation for this work is to demonstrate the rapid product development capabilities of the machine. The polymeric material used in this process is Acrylonitrile-Butadiene-Styrene (ABS). Its superior properties allow the MUAV structure to be built accurately to design specifications. The advantage of this approach is the shorter time required for design, fabrication and deployment.

Abstract: This paper analyzes the configuration of the transformer neutral protection principles and the whole interaction between the relevant relationship between protection and substation operation combined with practical action on how to protect the typical accident analysis, with strong practical significance.

Abstract: The composition and working principle of DCS control system is introduced, as well as Configuration，function and basic language. The design proposal of control system on melamine is related, and its advancement and importance of cascade control is further elaborated. Nowadays, the whole control rate can reach above 95%, which can lower labor intensity and improve working environment.

Abstract: Results of an experimental and theoretical analysis of the proprerties of a LD pumped laser using a stable resonator and second harmonic conversion crystal are presented. The influence of thermal lens effect on laser output mode and beam quality has been discussed briefly by using the transfer matrix theory. In this paper, further experiment on the output beam quality of a LD pumped acousto-optic Q-switched laser has been also performed by adopting Shack-Hartmann wavefront sensor and Zernike mode reconstruction theory. Using this method, PV and RMS error of aberration wavefront, the first 35-order Zernike aberrations can be acquired. Furthermore, Strehl ratio curve of output beam and the distribution of circle energy can also be obtained by further calculation, so mode properities can be comprehensively understood. Experimental results show that the beam wavefront aberration is mainly concentrated in the first 15 orders of Zernike aberration, mainly including the defocus A3, the low-order astigmatism A4 and A5, the coma and spherical aberration because of the thermal-lens effect.

Abstract: The uncertainty quantification for a flexible flapping airfoil was investigated using the point-collocation non-intrusive polynomial chaos method. The chordwise flexible amplitude was assumed to obey a normal distribution. It is observed that the time-averaged thrust coefficient obeys a Gauss-like but not the exact Gauss distribution, while the probability of the propulsive efficiency is much different from the exact Gauss distribution. The effect of the chordwise flexure on the time-averaged thrust coefficient is much larger than the effect on the propulsive efficiency. This work could be a preparation for the robust design of a flexible flapping wing with respect to a stochastic chordwise flexure.

Abstract: Stirring system of blender truck as an important equipment of fracturing unit, its stirring effect has great influence on performance of fracturing fluid and fracturing operation of fracturing unit, so it is necessary to study the influencing factors for stirring effect of blender truck. On the basis of the theory of the orthogonal test method and the requirement of the design on the stirring system, the factors and their levels of numerical simulation experiment are confirmed and the orthogonal test scheme is established in this paper. Also the numerical simulation for mixing process of stirring system of the blender truck is carried out with CFD software. The influence degree of the factors on stirring effect is obtained with the range analysis method, the optimal structure size of stirring system is achieved according to this result.