Applied Mechanics and Materials Vols. 66-68

Abstract: This paper presents a lateral Integrated Fire/Flight Control (IFFC) for a Reconnaissance and Strike integrated Unmanned Aerial Vehicle (R/S UAV). The system consists of a fire/flight coupler and an adaptive rolling angle controller. In order to improve the changeful dynamic in the rolling loop of the R/S UAV, a Neural Network (NN) is used to obtains approximate inverse dynamics of the response. Numerical simulation is performed using this method, and the results show that the proposed system improves the IFFC performance including the time delay and overshoot.

Abstract: Firstly, the basic thoughts of value chain are discussed. Secondly, combining the practical of the tobacco enterprise the application of value chain is analyzed in marketing process. Finally, the importance of the application of value chain is putted forward, in order to improve the competition of the tobacco enterprise. Case study shows that value chain analysis is useful and helpful for the tobacco enterprise management.

Abstract: The paper presents load analysis of a Superskin layered helmet by finite element method. Results are compared with those of conventional crash helmet to evaluate the performance of Superskin in preventing rotational injury to the neck of the rider. Delamination of Superskin is observed that increases the safety of the rider. Solid Works and Mechanical APDL (Ansys12) softwares are used in the analysis.

Abstract: The fatigue crack growth tests of compact tension (CT) specimens of 2024-T4 aluminum alloy were conducted under constant amplitude loading with different R-ratios, 0.05, 0.1, 0.5, 0.75, respectively. The thickness of the specimen is 3.8mm. All the fatigue crack growth experiments were carried out in ambient air without a pre-crack. The early crack growth region reflects the influence of the notch. An optical reading micrometer with a magnification of 40 was used to measure the crack length. The size of the notch together with the loading conditions has a great influence on the early crack growth within the notch influenced region. Beyond the notch influenced zone, the stable fatigue crack growth is reached and can be characterized by the Paris law. The experimental results indicate that fatigue crack growth rate increases with the R-ratio for a given stress intensity factor amplitude.

Abstract: The characteristics of the fluctuating pressure for the 15° expansion corner of an axisymmetric body have been investigated experimentally using dynamic pressure measurements and Schlieren photograghs. Data were acquired over a Mach number ranging from 0.8 to 0.92. The angles of attack ranged from 0° to 5°. Pressure signals were measured simultaneously in several positions along the axis of model and were analyzed both in the time and frequency domains. The results indicate that large fluctuating pressure loads, resulting from the shock/boundary layer interaction exist at the transonic flow condition, because of the shock/boundary layer interaction. The maximal pressure fluctuation occurs after the expansion corner at Mach number 0.86. With the Mach number increasing, the position of the normal shock moves downstream. In the shock/boundary layer interaction region, the fluctuating pressure changes significantly with different angles of attack. Moreover, this interaction has a main effect of enhancing the power spectral density in low-frequency range (f≤5KHz).

Abstract: The characteristics of the fluctuating pressure in the boundary layer of an axisymmetric body have been investigated experimentally using dynamic pressure measurements and Schlieren photograghs. Data were acquired at subsonic and super-sonic Mach numbers. The angles of attack ranged from 0° to 5°. Pressure signals were measured simultaneously in several positions along the model and were analyzed both in the time and frequency domains. The Mach number shows the relevant influence on . Furthermore, the pressure fluctuations’ level decreases with the increasing of Mach number except M=1.15. And it is shown that, the location along the axis of the model and the angles of attack have small effect on pressure fluctuations.

Abstract: In this paper, Au-Zn-Cu-Ni alloy series was take as a benchmark. Nickel element was replaced by Manganese in different ratios. The existing state and distribution law of Manganese, and the effects of the Manganese on microstructure and properties of gold alloys were studied. The mechanism of effects of Manganese on the colour and the release of nickel of gold alloys were discussed.

Abstract: A nanocrystalline (NC) layer with the thickness of 30 µm was produced on pure titanium surface by surface mechanical attrition treatment (SMAT). Microstructure observation indicated that the grain size increases with depth from the treated surface. The friction coefficient decreases and the wear resistance increases with the SMAT sample as compared to its coarse-grained counterpart. The improvement of the wear properties could be attributed to the higher hardness of SMAT sample.

Abstract: The main factor of rubber fatigue was stress field. But the way is not sensitive in many cases. To clarify which factors were the main for predict the locations of fatigue crack, we analyzed the factors of stress field and strain field of rubber joint, and relations between the factors and the locations of fatigue crack, using 3D FE simulation. The result showed stress concentration was not sensitive to predict the locations of fatigue crack. The locations are close to strain concentration of rubber joint. In this paper we propose the approach of using strain concentration to predict the fatigue crack locations for rubber joint. This result is significant for the rubber joint design and the study of fatigue strength theoretic.

Abstract: A finite element model of HSM (High Speed Machining) process of Ti6Al4V was developed with Abaqus 6.10. The flow stress of Ti6Al4V is taken as a function of strain, strain rate and temperature. Considering the fact that the tool edge radius is relatively large in HSM of Ti6Al4V and significantly influences the mechanical behaviour, thus a new Arbitrary Lagrangian-Eulerian (ALE) boundary technology was incorporated into the finite element model to simulate the flowing material around the tool edge.The adoption of ALE boundary technology could avoid using the traditional chip separation criterias and element deletion method in the model, which at the same time results in the less excessive element distortion and computational time in comparison with traditional finite element models of cutting process. The simulation results of Cutting force and temperature close to the experimental values in an acceptable range could be obtained and a stagnant zone in front of the tool edge was successfully observed in this new developed model with large tool edge radius.