Applied Mechanics and Materials Vols. 152-154

Abstract: The Kyoto Protocol established the reduction of pollutant emissions limits for all sectors of industrial economy in 8%, compared to 1990´s levels, to be adopted in the period between 2008 and 2012. Individual countries defined a progressive scale for the emission reduction applied to automotive vehicles. These new emission limits are reached altering the calibration of the Electronic Central Unit (ECU), altering the volume and the composition of the catalytic converters and also adding new components to the engine, such as EGR (exhaust gas recirculation) system and phasing sensor. This work evaluates the impact of these modifications in the exhaust system temperatures and in the peripherical devices. In order to meet the requirements of the new emissions limits, the volume of the catalytic converter is higher, increasing the heat rejected. It provokes a temperature raise on the exhaust system and under the vehicle pavement, which impact the functionality of some components and also the passenger's thermal comfort. It is observed that the new emission standards in Brazil resulted in an increase of the vehicle temperatures, affecting the passengers’ thermal comfort, and eventually producing more emissions due to the use of an air conditioning system.

Abstract: The equilibrium configurations of compressed elastic beams in an elastic medium are investigated. The analysis is performed on discrete models by means of a geometric non linear treatment. The effect of the elastic stiffness of the medium on the overall stability of the structural system is taken into account through a parameter which represents the ratio between the elastic medium stiffness and the beam stiffness. This parameter shows to have a great influence on the buckling and post-buckling behaviour of the structure.

Abstract: In the present work the evolutive laws and the constitutive relations for a model of nonlocal viscoplasticity are analyzed. Nonlocal dissipative variables and suitable regularization operators are adopted. The proposed model is developed within the framework of the generalized standard material model. Suitable forms of the elastic and dissipative viscoplastic potentials are defined and the associated constitutive relations are specialized. The evolutive laws for the proposed nonlocal viscoplastic model are presented in a general form which can be suitably specialized in order to include different models of nonlocal viscoplasticity.

Abstract: This article simulated the collision and agglomeration between bipolarly charged particles in an electrostatic agglomerator. The EHD turbulent flow was solved and the flow parameters were extracted a priori. The particle initial charge was obtained by tracking particles with a certain diameter in the charging zone. When simulating collision and agglomeration in the agglomerating zone, the initial charge on a particle was sampled from the charge distribution by statistical analysis. The classical stochastic model for calculating collision between neutral particles was extended to calculate collision between charged particles, and the effect of particle charge on collision and agglomeration was embodied in the agglomeration criteria. The effect of an external DC and AC electric field on the collision and agglomeration was investigated.

Abstract: Double-stage vibration isolation system can attenuate structure-born noise in media and high frequency band effectively, which improves the ship’s capability of concealment greatly. At the same time, this vibration control system can decrease the isolated equipment’s acceleration response while subjected to foundation shock excitation effectively. Hence ensure the isolated equipment’s acceleration response in a safety range. But the maximum displacement response of the isolated equipment will increase greatly at the same time. This requires that those flexible connecting components between the equipment and the environment should have great permitted displacement. If an auxiliary power system which can adjust the characteristics of the vibration isolations in the main system according to the vibration state is mounted on the middle mass block, it will output suitable force to attenuate the oscillation quickly to protect both the isolated equipment and the flexible connecting components under shock excitation condition. Simulation results show that this method is effective.

Abstract: This paper presents research and simulation analysis on kinematics and dynamics problem based on the 6-axis serial robot. By means of Denavit-Hartenberg method, the robot kinematics model is established as well as and the derivation process of kinematic and inverse kinematic resolution is described in detail. Furthermore, in software simulationX, robot system model including mechanical sub-system and control sub-system are founded. Additionally, through simulation, different performances of robot are illustrated based on different trajectory planning and control. In this way a theoretical reference is provided for the further study on trajectory planning and controls of 6-axis serial robot.

Abstract: How to quantificationally detect the damage of rocks is a key problem in damage mechanics for rocks, and it determined whether the damage theory of rocks could be brought into action in rock engineering. Detection techniques of rock damage were summarized and grouped into structural analysis approaches and feature measurement approaches, which include SEM analysis, CT detection, stress-strain measurement, wave detection, acoustic emission monitoring, infrared radiation detection, etc. Image processing and fractal theory were introduced to calculate damage variable directly based on images. All kinds of damage variables resulted from different methods are equipollent in thermodynamics, and they are an internal variable to characterize damage state. The difference of each kind of damage variable is that different formations of state equations and dynamic equations would be derived from different variables. It was suggested that the favorable rock damage variables should be selected according to the thermodynamics principle and those convenient to detect and easy to analysis should be adopted preferably.

Abstract: Vibratory feeders play an important role in automated systems and the decoupled vibratory feeder is a novel design which is excited in two different directions. The research on decoupled vibratory feeder concentrates on the modeling, the control system and structural optimization. The aim of this work is to focus on the integrated modeling of the decoupled vibratory feeder. The integrated modeling consists of the mechanic modeling, the electrical modeling and the control strategy. The modeling of all modules including the PID control, the power amplifier, the electromagnet, the feeder, the part motion and the feedback are discussed to reveal the relation between the input signal and the part motion. The block diagram of the integrated modeling of the whole system programmed with MATLAB is given in this paper. A deeper understanding of the decoupled vibratory feeder can be obtained by the integrated modeling to optimize the structural design and improve the conveying efficiency.

Abstract: It is known that vibratory feeders are the most versatile of all hopper feeding devices for small engineering parts and play a key role in assembly automation. However, there are still no reliable and effective professional teaching platforms for researching or demonstrating the principle of the parts conveying. The aim of this paper is to develop an optimal teaching platform based on the analysis of the working principle that the feeder follows. The structural design, elastic system and control system are studied in this paper. The vibration principle is verified by the teaching platform through the experiment and the results are promising.

Abstract: Based on the structural geology, sedimentology, palaeontology and geochemistry, the sedimentary facies and evolution patterns are developed in Songnan area from the studies of seismic data, cores, well logs, palaeontology and geochemistry. The result indicates that nearshore subaqueous fan, fan delta, braid delta and lacustrine had been developed in the fault depressions of Songnan area. From the margin to the depocenter of the basin, the sedimentary environments gradually changed from nearshore subaqueous fan, fan delta or braid delta to shore-shallow sediments and middle depth-deep lacustrine. Two stages are divided for the sedimentary evolution of Songnan area, namely the prior stage which appears with Yixian formation developing lava facies and pyroclastic facies; the other is the detrital rock facies ,which are developed from formation Jiufotang to Fuxin, is composed of nearshore subaqueous fan, fan delta, braid delta and lacustrine. Conclusion can be made that those sedimentary facies are controlled by the depth of water variation, which changed from shallow to deep, and then to shallow. Multiple source-reservoir-cap assemblage in vertical provided favourable condition for oil and gas pool forming.