Advanced Materials Research Vols. 378-379

Abstract: Based upon the vibratory equation and sound radiation impedance of a cylindrical shell, the sound field distribution of a finite cylindrical shell simply-supported at two infinite rigid cylindrical shells were resolved with considering the structural loss. An interface containing some buttons connected with all the programs was designed by using Matlab, and their data were all stored in a file. It has been shown that the sound radiation power of the cylindrical shell decreases and the radiation efficiency increases with increasing of structural damping loss factors; when the frequency of the driving force is low, the sound field shapes “∞” directivity pattern; When the frequency of the driving force grows higher the sound directivity pattern becomes complex due to superposition of axial modes and circumferential modes; Only when the radiation of the end plates is much weaker than the cylindrical shell the analytical results of the shell simply-supported at two infinite rigid cylindrical shells can be utilized to illustrate the sound radiation by a finite cylindrical shell with two end plates.

Abstract: With RMT-150C rock testing machine and AEWIN E1.86 DISP acoustic emission system applied, the acoustic emission test was accomplished with two kinds of rock samples including marble and granite under uniaxial compression. Cyclic loading and continuous loading were used through the experiment, and the mechanical performance and acoustic emission (AE) characteristics were obtained during the process of rock progressive failure. Details related to the relationship between amount of AE and stress-strain was given in this paper. A comparison between marble and granite was made as well following the general AE law, on the basis of which, the failure mechanism of rock mass was investigated. Finally, some conclusions can be summarized as follows:(1) AE activity features are different with stress state variation in rock failure process;(2) loading patterns make a direct impact on the failure process thereby affecting AE activities;(3)AE activities are various basing on the different types of rocks, structures and failure modes.

Abstract: The aim of this study is to fabricate WCp/Cu functionally graded materials (FGMs) and test its properties. Vacuum Hot-pressed Sintering technique is used to develop the graded WC particle reinforced Cu matrix composite. Using powder layering technique, a multi-layered WCp/Cu FGM have been prepared successfully. Scanning electron microscopy is used for microstructural analysis. Microscopic observations display that the microstructure of WCp/Cu FGM distribute gradually, and have no visible macroscopic interface. The mechanical properties of WCp/Cu functionally graded materials have been investigated, including Vickers's hardness, Young’s modulus and Tensile strength. Experimental results show that the properties of WCp/Cu FGM strongly depend on compositional variation.

Abstract: By studying on reliability model of aircraft structure holistic life assessment, several random parameters are chosen to analyze the randomness of aircraft structure life in this document, the sensitivity of random parameters is investigated to determine the important parameters. The fuzzy random parameters are also studied in this document, the influence of these parameters to aircraft structure reliability is analyzed in the final.

Abstract: The effects of carbonation age, fly ash content in the binder and the water to binder ratios on the carbonation depth of fly ash concrete is investigated and the micromechanical properties of the hardened paste and the inter facial transition zone is analyzed with the micro-hardness method. The experimental results show that replacing Portland cement in concrete with fly ash increases the carbonation rate at early ages, while the late age carbonation rate is lowered. Micromechanical analysis shows that the carbonation reaction increases the micro-hardness of the paste and the compactness of the ITZ. For the relative low replacement levels, the width of the ITZ is reduced if the concrete is carbonated.

Abstract: According to the chemical balance and the minimum free energy principle calculate explosive products and Detonation parameters, and then BKW equation was utilized to calculate JWL EOS parameters. Visualization software of Detonation and JWL EOS parameters was development, which was provided with favorable user interface. The calculation results and experimental data were basically consistent. The paper solved the bottleneck problems regarding the technology of numerical simulation of dynamic response and damage effect of Multi-phase explosion of explosive hazard sources.

Abstract: The incident wave and transmission wave varying with the time have been obtained by SHPB experiment. The relationship curve for stress and strain of material concrete has also been obtained. The Weibull function is used to describe the damage factor of the concrete. The damage factor of the concrete changing with the time under the impact conditions is obtained by the method of fitting the strain-stress relationship curves.

Abstract: In numerical manifold schemes for direct solution of steady Navier-Stokes equations, mixed cover for velocity and pressure was adopted in finite element cover system. The patch test of numerical schemes was investigated, mixed cover manifold element has been proved to meet the stability conditions, and can be applied to directly solve Navier-Stokes equations coupled velocity and pressure. As an application, the numerical manifold schemes were used to simulate the steady flow past a step. Numerical solutions illustrate the stability of numerical manifold schemes, and it indicates that manifold method is an effective numerical method for steady Navier-Stokes equations.

Abstract: A model for wave propagation in variable cross-section bars is developed. Then a numerical simulation method based on CSPM is introduced. Furthermore the wave propagations in stepped bars and conical bars are simulated. The simulation results agree well with the analytical solutions, which demonstrate that the model can describe the wave propagation in variable cross-section bars precisely.

Abstract: The companion paper presents experimental results and numerical simulation methods to illustrate the behavior of FRP sandwich panels under synergistic effects of low temperature and cyclic loading. This paper aims at verifying the proposed simulation methods and providing several examples of its application to FRP sandwich panels. In this regard, four categories were simulated including: perfect bonding, microcracks, debonding Case I, and debonding Case II. Each category contained six ABAQUS models with two types of loads, thermal loads and applied mechanical loads. Results showed that microcracking would lower the stiffness of the panel, but not as much as debonding between the core and the face sheets.