Applied Mechanics and Materials Vols. 184-185

Abstract: Accurate simulation for airflow structural characteristics in the human mouth-throat model plays an important role in analyzing the filter effect of pharynx and larynx and the diffusion, transition and deposition patterns of aerosol in human upper respiratory tract. Large eddy simulation was used to simulate the airflow movement in human mouth-throat model in the conditions of the cyclic respiratory pattern, and the airflow structural characteristic in mouth-throat model was discussed. The results show that two velocity growth points generated in pharyngeal and laryngeal region; the airflow separates in region near the pharynx and the separation zone appears near the anterior wall of pharynx; A turbulence jet appears in the glottal region and the airflow; the high velocity zone is created in pharynx and larynx, and the phenomenon of airflow separation appeared in the pharynx. In the process of cyclic exhalation, the phenomenon of airflow separation didn’t appear in the pharynx and larynx.

Abstract: This paper introduces the measurement systems of the oil cylinder in automatic wheelset assembly machine, theoretically analyzes the error of the displacement measurement system by curve fitting, and gets verification the error analysis in practice. This paper also calibrates pressure sensor from zero drift, slope of the output of the pressure sensor to guarantee the system pressure, and compensated pressure sensor value consistent.

Abstract: This paper proposes the conditions of no-undercutting and contact-retaining of the disc cam mechanism with negative radius roller follower. Then, it presents the contact stress expression based on the mechanical analysis. In addition, the effects of different parameters on the force and contact stress are analysed. The results show that the contact stress can be reduced by designing the suitable parameters of the cam.

Abstract: The stability problem of eccentric rotor in high-speed cutting process is the main factor affecting the performance of cutter transmission system. A modal analysis of eccentric rotor for multi-layer leather high-speed cutting machine based on bond graph method is proposed to obtain the complete modal parameters. The lateral vibration mathematical model of the eccentric rotor is build using bond graph theory. The inherent frequency, deformation modal vibration shape, and velocity modal vibration shape of eccentric rotor are obtained through the Matlab numerical calculation. Then the modal test for eccentric rotor is done and the compared results are given. The results show that using the bond graph method solves the problem more easily than Newton's theory, obtains the two type of modal vibration shape, and its relative error is less than 0.4%. The complete modal information is given that provides a theoretical basis to better understanding the dynamic properties of eccentric rotor and provides the basic parameters for dynamic performance optimization and dynamic balancing analysis of cutter transmission system.

Abstract: In this paper, the influence of thermal accumulation on the deposition trajectory quality during the plasma deposition process was investigated. The energy balance model in the deposition process was analyzed and an adaptive gas cooling subsystem to diminish thermal accumulation during manufacturing process was developed. The subsystem consisted of gas cooling rotation device driven by step motor and a special CAM program. Experiments were carried out to verify the validity of the adaptive gas cooling subsystem. Results showed that the application of adaptive gas cooling subsystem effectively suppressed the thermal accumulation during the manufacturing process and eliminated the collapsing of the deposition trajectory.

Abstract: The multi-objective design optimization of cooling turbine blade is studied using Kriging model. The optimization model is created, with the diameter of pin fin at the trailing edge of cooling turbine blade and the location, width, height of rib as design variable, the blade body temperature, flow resistance loss and aerodynamic efficiency as optimization object. The sample points are selected using Latin hypercube sampling technique, and the approximate model is created using Kriging method, the set of Pareto-optimal solutions of optimization objects is obtained by the multi-object optimization model using elitist non-dominated sorting genetic algorithm (NSGA-Ⅱ) based on the approximate model. The result shows that the conflict among all optimization objects is solved effectively and the feasibility of the optimization method is improved.

Abstract: Non-uniform motion mechanisms (NUMM) utilized in a Twin-rotor piston engine (TRPE) are introduced. TRPE mechanism consists of two major components. One is energy conversion system (ECS), and the other is differential velocity drive mechanism (DVDM). DVDM is composed of NUMMs and ordinary gear train in this paper. NUMMs generate two non-uniform rotations with same pattern and different pace. Gear train duplicates the two rotations and causes the two rotors rotating with periodical oscillation.

Abstract: Abstract: Method of CFD is used to simulate flow fields for a certain Axisymmetric nozzle, The paper describes the grid adaption, boundary conditions determination as well as RNG model application, and analyzes the nozzle aerodynamic characteristics. The numerical results match well with test data.

Abstract: During the start-up of ignition process, the solid rocket motor is typically involved in fluid-structure coupling process. The propellant deforms under the gas pressure, thereby influents the gas flow in turn. The aim of this paper is to investigate the coupled effect between fluid and structure during the start-up of ignition process in solid rocket motor by coupling Fluent and Abaqus via MpCCI. The numerical result shows that during the initial stage, the gas flows onto the structural surface. There is a relative enclosure space in thewing slot inside the motor, which causes big deformation on propellant grain and stress reliever. This space is the high-risk area for structural deboning in solid rocket motor.

Abstract: Abstract. As an innovative process of manufacturing ultra high strength steel (UHSS), hot stamping or press hardening is a multi-physical coupling process with complex changes in thermal, mechanical and phase transformation. In this work, in order to study heat transfer from workpiece to upper & lower die and cooling water, a new approach, named Bulk Flow, is adopted to model the cooling ducts and to simulate heat transfer in hot stamping die. Not only can tool design, cooling duct layout and process parameters be studied and optimized to increase the cooling rate and to homogenize temperature distribution in workpiece, but also, the precision of hot stamping simulation be improved. The experimental results of boron steel components formed by the designed die show that the martensite is homogenous. It indicates the feasibility of the bulk flow method．