Advanced Materials Research Vol. 853

Abstract: A series of new nitropyrazole explosive molecules were designed with N-nitropyrazole as structural unit, The detonation parameters of nitropyrazoles explosives, such as detonation velocity, detonation pressure, detonation temperature, detonation volume, were estimated theoretically in different methods, The calculated detonation pressure was corresponded with high energy density material (HEDM). Their detonation velocity and detonation pressure are between those of TATB and HMX. These compounds have higher detonation temperature and heat of detonation compared with HMX and TATB. It was predicted that these explosives are of favorable stability.

Abstract: History of Computer Aided Manufacturing (CAM) becomes from 50th years, when the conception of numerically controlled (NC) machines was designed. This was first impulse for entrance of electronics and later computer technology into the production support. However, more extensive development of CAM systems was enabled by creating the conception of the computer numerically controlled (CNC) production machines which is dated to 1970. Since the CAM systems allow the data about product geometry, which has been created by CAD system, to be used directly for creating NC programs for NC and CNC production machines.

Abstract: This article concludes a calculation method which is suitable for most of the military aerodromes based on the research about the size of setting aircraft stop sand. It also provides suggestions and theoretical basis to the setting of aircraft stop sand in future.

Abstract: Explosion-proof elevator has been more and more widely used in the flammable, explosive places. Because of the particularity of the environment, in the design of explosion-proof elevator, various approaches are taken to achieve the purpose of explosion-proof, such as explosion isolation and intrinsically safe circuits. Besides, it is important to pay special attention to the collision and friction between various parts of the elevator. As well as elevators traction sheave and hoist ropes, over-speed governor sheave and ropes are also the main parts which generate thermal energy easily when there is friction happened. In this article, a finite element method (FEM) is used to simulate and analyze the thermal energy generated in those two parts with a purpose to test the performance of explosion-proof.

Abstract: In petroleum, chemical, metallurgical and other industries, a special kind of elevator, the explosion-proof elevator, is applied due to the existence of flammable and explosive substances in the environment. Explosion-proof elevator has adopted various approaches to meet the requirements of explosion-proof areas levels in the design stage, such as explosion isolation and intrinsically safe circuits. However, in normal working process, thermal energy will be generated by the friction occurring between different components of an elevator, which is very dangerous if the temperature of the assembly exceeds the limited value of related standards. Frictions always occur between guide shoes and guide rails when the elevator operates .Similarly, there are also frictions between safety clamp blocks and guide rails when the safety gear works. In this article, a finite element method is used to simulate and analyze the thermal energy generated in those two parts with a purpose to examine the performance of explosion-proof.

Abstract: Thanks to the development of microprocessors, hybrid stepping motors have been widely used in many areas where they perform positioning operations. However, the stepping motor suffers from system variations, low performance and lack of adaptability to load variations, which slow down their responding speed of high-precision positioning operations. In this paper, a computational verb PID controller is proposed to control the position of a stepping motor drive. The simulation results show that the computational verb PID controller has better performances than conventional and fuzzy PID controllers. The simulation results also show that the responding speed and positioning accuracy of the controlled hybrid stepping motor were greatly improved. Computational verb PID controller has much less computational complexity than fuzzy PID controller.

Abstract: The design of the footrest used in the auto seat was investigated based on the ergonomics. According to the results, the design path along with the type of the footrest could be described as: i) an adjustment mechanism is necessary for the footrest to meet the requirements of the different groups; ii) the adjustor of the footrest could be realized by using a ratchet mechanism and iii) the hand-operating should be avoided for the using of the footrest and the footrest should be self-closing when it was free of use to realize the passenger protection.

Abstract: This paper is to investigate the characteristics of re-use precision locknuts of the machine tools spindles in the vertical assembly under different effective diameters, locking axial forces and clasp screw locking torques in the static tests for the axial force change rates. The results with the new flank locking precision locknuts are compared to the re-use nuts with different values; we obtain the decline of axial force change rates from predetermined equations using regress analysis to conduct experimental forecasts. In the experimental results, plastic deformation has occurred in re-use nuts structure in the vertical spindle assembly. The decline of the axial force will be increased along with the nut size; and those of the re-use nuts decline more than the new nuts. Therefore, repetitive uses of the reuse nuts are not recommended.

Abstract: As the machine tool industry moves towards high speed and high precision, we must have detection technology for the mechanical properties of fasteners, in order to overcome technical bottlenecks. This article is especially aimed at machine tools and special-purpose machines that commonly use clasp locking precision locknuts. In this research, the anti-loosening characteristics of precision nuts are investigated under different conditions, such as the clearances, end processing methods, nut cutting speeds, lubricants, and tightening speeds. The results can provide the precision nut manufacturers a data base for product design. The experimental results show that with the end surface machining method using concentric grinding, nut cutting speed 800rpm, 2rpm speed of tightening, and the use of lubricant 2TML, the nut has better anti-loosening characteristics.

Abstract: The flutter analysis of a wing with an external store is presented. Because of the external store, the concentrated store mass is combined into the governing equations which are obtained using the extended Hamiltons principle. Dirac function is used to precisely consider the location and properties of the external store. The k method is used to calculate the flutter velocity. The effects of store parameters such as store mass and inertia on the flutter velocity are investigated.