Applied Mechanics and Materials Vols. 66-68

Abstract: Coiled tubing (CT) and coiled tubing units (CTU) technology has been widely used in oil and gas field since World War II. Coiled tubing fatigue failure is one of the constraints on promoting used. CT bears complex loads, leading to multiple plastic deformations when operating. Then the fatigue damage cannot be ignored. Through the mechanics analysis of CT with finite element method (FEM) in working state at the wellhead, the results show that high stress and high strain are the main factors which cause CT failure. Based on the analysis, the fatigue life is predicted for CT without defects by using Manson-Coffin formula. The results of CT with different inner pressure show that simulations result is closer to the actual working conditions.

Abstract: Researching and developing chrome-free refractory becomes a research hotspot at present because hexavalent chromium ions (Cr⁶⁺) may lead to environmental hazard. The additives lanthanum oxide (La₂O₃), effect on mechanism of spinel refractory react with cement clinker, several additives, such as cerium oxide (Ce₂O₃), titanium dioxide (TiO₂), barium oxide (BaO), iron oxide (Fe₂O₃), are researched in this paper. It indicates that La₂O₃ is a suitable additive to MgO-MgAl₂O₄-ZrO₂ brick which not only could stabilize phase transition of dicalcium silicate (C₂S) in cement, but also do not impair the high-temperature-properties of spinel. The new environmentally friendly material spinel and lanthanum zirconate Composite is an excellent refractory for cement kiln which has high thermal shock resistance, good coating adherence, good corrosion resistance, higher mechanical strength, and longer service life than magnesia-chrome brick when they are used for sintering zone in cement kiln.

Abstract: Experiments were conducted in a horizontal multiphase flow test loop (50mm inner diameter, 40m long) to study the flow patterns for oil-gas-water three-phase flow and the pressure gradient fluctuation based on flow patterns. Using new methods of definition, 12 types of flow patterns were obtained and phase distribution characteristics of each pattern were analyzed. A new flow pattern (SW║IN) was firstly found in this work. Characteristics of the pressure gradient based on 7 flow patterns were carefully discussed. It was found that the pressure gradient increased with the increase of gas superficial velocity and oil-water mixture velocity. However, characteristics of the pressure gradient became complex with the increase of input water cut. The influence of flow structure of oil-water two-phase should be fully considered.

Abstract: A series of Pd-CeO₂/γ-Al₂O3 catalysts which have a different CeO2 loading were prepared by impregnation under microwave irradiation. Based on various characterizations, such as XRD, H₂-TPR and CO-TPD, the effect of CeO₂ loading on catalytic performance and stability of Pd/γ-Al₂O₃ were examined for one-step dimethyl ether synthesis from syngas. The results show that there are two completely opposite effect on the CO conversation rate of Pd/γ-Al₂O₃ catalysts after adding CeO₂, namely that it can improve Pd dispersion at a suitable loading, hence the CO conversation rate will increase too. However, the surface area and total pore volume of Pd/γ-Al₂O₃ catalysts decrease by adding excessive CeO₂ and CO conversation rate will also reduce. When the CeO₂ loading achieve to 2%, catalysts can have relatively high catalytic stability and activity that the CO conversation rate and DME space-time yield can reach 64.7% and 27.82 mmol·ml^-1·h^-1, respectively.

Abstract: In recent years the wind turbine blade has been the subject of comprehensive study and research amongst all other components of the wind turbine. As our appetite for renewable energy from the wind turbine continues to increase, companies now focus on rotor blades which can go up to 80m in length. The blade material not only have to face large aerodynamic, inertial and fatigue loads but are now being designed to endure environmental effects such as Ultraviolet degradation of surface, accumulation of dust particles at sandy locations, ice accretion on blades in cold countries, insect collision on blades and moisture ingress. All this is considered to ensure that the blades complete its designated life span. Furthermore exponential increase in composite blade manufacturing is causing a substantial amount of unrecyclable material. All these issues raise challenges for wind blade material use, its capacity to solve above mentioned problems and also maintain its structural integrity. This paper takes on this challenge by optimizing from the properties, merits, demerits and cost of different possible competing materials. Then the material is checked for its structural integrity through Finite Element Analysis simulation using standards like IEC-61400-1.This paper also shows the future direction of research by elaborating the influence nanotechnology can have in the improvement of the wind blade.

Abstract: Vibrational moulding process has a remarkable effect on the properties of castings during solidification processing of metals, alloys, and composites. This research paper discusses on the investigation of mechanical vibration mould effects on the tensile properties of titanium carbide particulate reinforced LM6 aluminium alloy composites processed with the frequencies of 10.2 Hz, 12 Hz and 14 Hz. In this experimental work, titanium carbide particulate reinforced LM6 composites were fabricated by carbon dioxide sand moulding process. The quantities of titanium carbide particulate added as reinforcement in the LM6 alloy matrix were varied from 0.2% to 2% by weight fraction. Samples taken from the castings and tensile tests were conducted to determine the tensile strength and modulus of elasticity. The results showed that tensile strength of the composites increased with an increase in the frequency of vibration and increasing titanium carbide particulate reinforcement in the LM6 alloy matrix.

Abstract: This paper presents a method for estimating the vehicle structural weight in the conceptual design phases of reusable launch vehicles and analyzes the sensitivity of the multi-factors which affect the structural weight. The method is an application of liner regression analytic methods. Based on the analysis about the statistical data of the overall parameters of the vehicles, the estimating formulas of the structural weight for the vehicles are deduced using the method. By defining a sensitivity function and a sensitivity factor with dimensionless, the sensitivity of the estimating formulas to every overall parameter is analyzed. Numerical examples and the sensitivity tests indicate that those estimating formulas are available and practicable, and that wing aspect ratio, trapezoidal wing area, fuselage structural depth, vertical tail area and tail length are the most important factors that greatly affect the structural weight.

Abstract: A numerical method has been developed to analyze the solid-liquid two-phase flow with coarse particles in vertical pipes. Based on the numerical study, a concept of lifting efficiency has been suggested to describe the efficiency of lifting solid particles by the moving liquid. The lifting efficiency can be defined as, where v_s is the average velocity of the solid particles and v_l is the average speed of the liquid. It was found that when the liquid speed is lower than 3m/s, the lifting efficiency is increased when the liquid speed is increased. On the other hand if the liquid speed is more than 3m/s, the lifting efficiency will decrease if the liquid speed increases. It was also found that the speed of the particles will decrease if pipe vibration frequency is increased. However the lifting efficiency remains unchanged compared with the stationary pipes.

Abstract: Based on the bionics principle, this paper proposed the idea of bionic design of the spherical parallel shoulder joint integrated with the six-component force sensor. The static analysis of the 3-RRS mechanism, which can be taken as a prototype mechanism of shoulder joint of humanoid robot, was carried out. And the relationship figures between the forces and torques acted on each component and the pose of the mechanism were obtained. The measurement of the external load and driving torques, which was employed to judge operability of arm to the target object under arbitrary pose, was realized by introducing resistance measurement method in the mechanism. The bionic integration of the shoulder joint with six-component force sensor made arm has some functions such as to avoid overload and singular area voluntarily, and realize self-protection. The contents of this paper lay a foundation of compliant control of humanoid robot arm and have important significance and value in engineering.

Abstract: The 3S education in carbon cycle by Webgis has been studied in the paper. Ways of 3S education in carbon cycle are introduced in the paper. By analysing these ways of 3S education, a new way by the help of Webgis is chosen. Two classes are chosen to test the way. The result of the test tells us that Webgis can help students in 3S education in carbon cycle.