Applied Mechanics and Materials Vol. 312

Abstract: In this paper, the differential equations of the steel rope shock absorber are established under the basic excitation, using the Fourier series expansion method and the Harmonic balance method, the corresponding frequency response equations are derived, then their numerical solutions is got, and the influence of the mass, damping, stiffness, and hysteretic force on the frequency response characteristic is analyzed under the basic excitation. It can be drawn by analyzing and comparing. Under the basic excitation, with the basic simplified mass increasing, the natural frequency will decrease, while the resonance amplitude will increase. With the steel rope damping, stiffness and the foundation damping increasing, the natural frequency will not change significantly, while the resonance amplitude will decrease. With the foundation stiffness increasing, the natural frequency and the resonance amplitude will increase significantly. The equipment mass and steel rope hysteretic force have no significant effect on the frequency response characteristics.

Abstract: This thesis constructs the dynamical model of the imbalance-misalignment coupling faults and the finite element model of the rotor system which are supported by rolling element bearing. It analyses the impacts from the coupling faults to the system on the basis of nonlinear finite element method, dynamic theory and Newmark-beta numerical integration method. It also studies the influence of the unbalance, misalignment and coupling faults to the system by applying the dynamic response chart and time-frequency properties. The study shows that there exist unstable high and low harmonic components, the unbalanced signal overshadowed by misalignment. It also discovers that besides the working frequency, there also exist tow times frequency and other high doubling components on the response spectra with two times frequency for the most. All those study results provide some theoretical reference for the fault diagnosing of the rotor bearing system, the vibration control and the stability research.

Abstract: According to the international standard ISO 9614-1:1993 " Determination of sound power levels of noise sources by the sound intensity method - Part1: Measurement at discrete points, the sound intensity test was conducted on the acoustic enclosure for the refrigeration compressor with the PULSE software. The sound insulation performance of the acoustic enclosure was analyzed by comparing the compressors noise with and without the enclosure. The result shows that the noise of the compressor with the acoustic enclosure is less than 60dB (A), and the high-frequency noise can be greatly reduced, which meets the design requirements of noise control. Therefore, it is easy to conclude that the sound insulation of the acoustic enclosure reaches the design standards and the acoustic enclosure design is feasible. The paper provides a valuable reference for the further study on the designing and optimizing of the acoustic enclosure.

Abstract: The transverse vibration characteristic of the viscoelastic sandwich beam with axial speed is studied under the coupled temperature field and displacement field. Based on the theory of Euler - Bernouli beam and the constitutive relation of Kelvin viscoelastic material model, the transverse vibration equation of the axially moving beam is established ; considering the interaction of the material deformation and the heat conduction, the coupled governing equation of the beam is obtained. and the coupled thermoelastic dynamics system are obtained by Galerkin method. The related thermal parameters on the vibration frequency are analyzed by using numerical method.

Abstract: The three-dimensional solid modeling is built based on some Automobile gearbox Product, the dangerous working conditions of static load are analyzed. On the basis of ADAMS, transient dynamic loads of gearbox at different working gears are found out. The finite element analysis modeling of gearbox casing is built. The static displacement and the stress distribution of gearbox casing are obtained, and the static strength and stiffness are evaluated. The eigenvalues of vibration of gearbox casing are solved, the coupling relationship of the excitation frequency and the gearbox casing natural frequency is analyzed. Based on the transient dynamic analysis of gearbox casing at the first gear and the reverse gear, the evaluations of the dynamic strength and dynamic stiffness are obtained and the weak position of structure is found out, which provides the beneficial information for the further study on the design of the fatigue and reliability of gearbox casing.

Abstract: In-situ micro/nanosized TiB₂ and Al₂(Y, Gd) particles reinforced magnesium matrix composite was successfully fabricated by addition of Al-Ti-B preform into Mg-Gd-Y-Zn matrix alloy, its microstructures and properties were investigated. The results show that the introduction of Al-Ti-B preform causes the precipitation of Al₂(Y, Gd) particles and the SHS synthesis of TiB₂ particles which significantly refine solidification structure. The reinforced Al₂(Y, Gd) particles with average sizes of 5-8 μm are uniformly distributed throughout the magnesium matrix, and have a good bond to the matrix. Tensile tests indicate that, compared with the former matrix alloy, mechanical properties of the multiple in-situ particles reinforced composite are improved all-roundly.

Abstract: To study the effects of different raw materials and concentration on properties of natural cellulose films, the dissolution of different raw materials and propyl gallate (PG) in N-methylmorpholine-N-oxide (NMMO) by rotary vacuum evaporation machine were operated, and glycerol was used as plasticizer. The results show that the mechanical properties, oxygen barrier, moisture barrier, transparency of the films which used cotton pulp as raw materials are superior to wood pulp and reed pulp. Cellulose concentration increase from 5% to 7%, the elongation, oxygen permeation flux, water vapor permeability, light transmittance decrease by 17.2%, 1.4%, 4.4%, 16.6%, respectively, the tensile strength of cellulose film increases by 103.1%.

Abstract: t is a developing trend for the filter aids industry that producing filter aids using the diatomite concentrate of beneficiation owing to the limited resources of high quality diatomite. In the present paper the characteristics of diatomite concentrate from LinJiang were studied systematically. Additionally, blending processes of diatomite with flux, disintegration methods after calcination, effect of distribution of size and soaking time of filter aids on the permeability are explored. It is expected to be significative to the industries of filter aids preparation and filtration applications.

Abstract: This article have reviewed the preparation processes, flow path and methods of today's high-performance mesophase asphalt-based carbon fiber, and illustrated the advantages of preparation of high performance asphalt-based carbon fiber. Besides, today's main methods of preparation of asphalt-based carbon fiber have been found, and the key problems of preparation of high performance carbon fiber have been figured out.It is very complex and difficult to control accurately. Preparation of mesophase asphalt-based carbon fiber is mainly reflected in the following points: (1) The selection of asphalt; (2) The quality of the spinning; (3) The effect of oxidation treatment; (4) The temperature during carbonization and graphitization process.

Abstract: The homogeneous grafting of methyl methacrylate (MMA) onto cellulose was carried out by using ammonium persulfate as an initiator. DMAc/LiCl was used as the solvent for the dissolution of cellulose and the media for the homogeneous graft polymerization of MMA onto cellulose. The efficient reaction conditions of the grafting reaction were confirmed by weighing methods. The results showed that the efficient reaction conditions were as follows: reaction time, 2h; mass ratio of MMA/cellulose, 1/1(g/g); mass ratio of initiator/cellulose, 6/50 (g/g); and reaction temperature, 80°C. Under these conditions, the GP of homogeneous grafted cellulose can reach 76%. The grafted polymer was characterized by FTIR, SEM and TG-DTA.