Advanced Materials Research Vols. 284-286

Abstract: This paper is focused on deriving an analytical solution to predict the transient temperature distribution on the plate during the process of Submerged Arc Welding (SAW). An analytical solution is derived from the transient three-dimensional heat conduction equation. The energy input that is applied on the plate is taken as the volume of heat lost from the electric arc. The electric arc is assumed to be a moving double-ellipsoidal heat source with a close proximity to a Gaussian distribution. It is observed that the predicted values are in good agreement with the experimental results. HAZ width calculation is also done with the help of the analytical solution of the transient-three dimensional heat conduction equation. Very good agreement between predicted and experimental values has been archived.

Abstract: The die base is the most complicated standard part of stamping dies. In the design process of stamping die, die bases are used repeatedly. This paper takes improving automaticity of three-dimensional modeling of die base as a starting point, discusses the parametric modeling process of die base with the dimension-driving method and provides a line of thought for other standard parts of stamping dies.

Abstract: A new method of CNC machine tool servo system fault diagnosis expert system is proposed.We analyse and design the protype structure of CNC machine tool servo system fault diagnosis expert system base on the methods and theories of expert system. Feasible for the establishment of the expert system are described from knowledge base to reasoning model,and we also provide an important basis for the establishment and development of the expert system.

Abstract: Marine gas hydrate is a new energy in the 21st century with the huge amount of resources and cleaning. But its decomposition and the release can lead to decrease the stability of seabed, causing submarine landslide. And its overflowed can intensify the greenhouse effect, interaction between which can lead to more serious ecological and environmental disasters. All of the exploitation technologies, such as depressurization, thermal methods, chemical injection method, CO₂ replacement method, and fluorine gas+microwave method, are limitations in controlling of the decomposed rates and decomposed range. The research based on the marine gas hydrate decomposition caused by vibration, by adjusting the excitation intensity, frequency, and amplitude. Different local oscillator strength applied on the occurrence of gas hydrate layer. Gas hydrate stable state changed in mining region, prompting the gas hydrate conversing from the sediments. Model of the experiment is made for simulations on the decomposition of gas hydrate. This method has a good controllability for the region and the process of mining, avoiding geological disasters and environmental issues in the seabed caused by the mining process.

Abstract: Polymetallic nodules/crusts are one of the most important mineral deposits in the ocean, in which iron, manganese, copper, cobalt, nickel and other metals are rich, and rare earth elements are rich, too. In this study, the contents of 11 rare earth samples in polymetallic nodules/crusts from the Pacific, Atlantic, Indian Ocean and north of the South China Sea are analyzed. The average content of rare earth in polymetallic nodules/crusts is 1265.57×10^-6, the average content of nodules is 1096.96×10^-6, and the average content of crust is 1623.88×10^-6. The enrichment of rare earth elements is controlled by iron and manganese oxides and clay minerals in nodules/crusts, which could absorb rare earth elements from seawater and sediment. Ce elements are highly enriched, making polymetallic nodules/crusts become the first used rare earth elements in mineral development.

Abstract: Due to the missile in flight, the airflow temperature around the missile body shall rise and the surface of the missile body shall also be heated. It introduces the engineering calculation method of thick wall aerodynamic heating of the missile, including air flow parameters, heat exchange coefficient and the head surface temperature calculation formula of the missile body.

Abstract: TiB₂-TiN composite films/SiC films (SiC films as interlayer) were deposited on biomedical titanium alloy (Ti6Al4V) through magnetron sputtering technique. The friction/wear behaviors of the TiB₂-TiN composite films under Kokubo simulation body fluid (SBF) were investigated. The results show that as sliding against Si₃N₄ ball (4 mm in diameter) at 200g load, the TiB₂-TiN composite films exhibited the superior friction/wear properties with the friction coefficient of 0.22, the special wear rate in the magnitude order of 10⁻⁶ mm³ m⁻¹ N⁻¹ together without interface delaminating. It was found that the films exhibited navel adhesion to Ca and P elements in Kokubo SBF. The present results demonstrate the possibility of developing the surface modification procedure of combining superior wear resistance and good osseointegration for application of orthopaedic implants.

Abstract: Geometry parameters, material properties and applied loads of the gear box are regarded as normal random variables. A model of reliability optimization design of the gear box is introduced. Two objective functions are selected. The Monte Carlo simulation of reliability calculation is presented. With rapid increasing of the speed of CPU, it is a feasible method. The optimization effect is very good.

Abstract: A new coagulant for spilled oil with bentonite and CaCl₂ and sawdust has been done in our lab. The experiment indicates that bentonite is a good coagulant, especilly accompany with CaCl₂ and sawdust. The function of bentonite is coagulation, adsorption and emulsification. CaCl₂ is a good coagulant-mate, and strengthen the coagulating function of bentonite. It can be used as the source of calcium ions, which can strongly adsorb on both bentonite and oil droplets, and is helpful for the coagulation between bentonite and oil droplets. Sawdust is also very important, its function is buoyant, bridge-made and adsorbent.

Abstract: The experiments of certain aluminum alloy plate penetrated by 7.62mm armor piercing projectile were carried out, then a penetration model of aluminum alloy plate impacted by 7.62mm projectile was created by using ABAQUS software and Johnson-Cook constitutive equation, and the distribution of stress during penetration process was analyzed. Experimental and simulation results show that the penetration model can simulate the shape and depth of crater, and the outputs of stress and strain during penetration process can provide basis of the formation mechanism of adiabatic shear bands for aluminum alloys.