Advanced Materials Research Vol. 871

Abstract: This research work is investigates the processes of structure formation in the samples were 110Г13Л subjected to shock loads. The processes of structure formation, initiated by shock waves are explained from the terms of new theoretical developments. Analysis of the results can be extended to a wide range of materials.

Abstract: We tried to combine the basic principle of grammatical evolution with vortex-ring-fractal structures of atoms to create new molecule structures. This approach combines knowledge of evolutionary optimization with physical chemistry.

Abstract: Polyurethane (PU) S80A was used as the material of the elastomer of the shock programmer in this paper. To validate Ogden hyper-elastic material model in simulation, the small impact test was performed. As the comparison for the time history of the acceleration between the impact test and simulation was performed. Using the cylindrical shock programmer, the constant used in Ogden hyper-elastic material model was calculated. The wave shape of the acceleration was obtained with the noised sign. To clearly obtain the wave shape of the acceleration the cylindrical shock programmer, the truncated conical shock programmer was used. Using the Ogden hyper-elastic material model, design variables of the shock programmer with the truncated conical shape was studied. Using the shock programmer with truncated conical shape the range on the level and time duration of the acceleration in simulation was from 494.9 m/s² to 10941 m/s² and from 1.3 msec to 23.5 msec, respectively.

Abstract: The stress relaxation modulus E(t) is one of the most important properties of viscoelastic materials such as solid propellant, and it is used to define the viscoelastic behavior based on the influence of time and temperature. In this paper, stress relaxation tests are conducted under constant strain 2% for 600 seconds in the range of temperature 60°C to-60°C and tensile tests are performed for solid propellants under constant cross head rate 5 mm/min in the same temperatures as stress relaxation tests. Based on the results, time-temperature shift factors are obtainedby shifting the relaxation modulus curves horizontally and the master curve of relaxation modulus is generated. The master curve of relaxation modulus according to classical method and Williams-Landel-Ferry (WLF) method are discussed. Also, the master curve of tensile properties are drawn using predetermined shift factor and the results are discussed.

Abstract: Hybrid composites of municipal solid waste (MSW)/banana fiber reinforced urea formaldehyde are prepared with different filler ratio. Mechanical properties such as tensile, flexural and impact strengths are investigated as a function of total volume fraction (V_f) of filler (MSW and banana fiber) and its chemical modification. The mechanical properties are found to be high at 40% V_f of filler which indicates effective stress transfer between fiber and matrix. It is observed that presence of banana fiber provides better mechanical properties to composites. The chemically treated composites showed higher tensile and flexural strength compared to untreated composites due to the strong interfacial interaction between the resin and fiber.

Abstract: The combustion process for using municipal solid waste as a fuel within a waste to energy plant calls for a detailed understanding of the following phenomena. Firstly, this process depends on many input parameters such as proximate and ultimate analyses, the season of the year, primary and secondary inlet air velocities and, secondly, on output parameters such as the temperatures or mass fraction of the combustible products. The variability and mutual dependence of these parameters can be difficult to manage in practice. Another problem is how these parameters can be tuned to achieving optimal combustible conditions with minimal pollutant emissions, during the plant-design phase. In order to meet these goals, a waste-to-energy plant with bed combustion was investigated by using computational fluid-dynamics approach.

Abstract: The material properties are strongly depended on the microstructure. Recently, for modeling and prediction of microstructure evolution during the forming processes a cellular automata method is used. Combination of several methods in multiscale model allows to extend the possibilities of each method and obtain more reliable results, which are close to the real conditions. The objective of this study is development of multiscale model of microstructure evolution during the shape rolling process and use it for simulation of rolling of 5 mm round bars. Model uses for calculations the finite element (FEM) and cellular automata (CA) methods. Modeling consists of three stages: design of the shape rolling schedule with the definition of shape and sizes of grooves (FEM simulation of each pass, starting from the last pass), FEM modeling of shape rolling in the proper sequence of the passes, modeling of microstructure evolution by frontal cellular automata (FCA). Stages (especially the last two) can be repeated several times to optimize the technology in view of final microstructure. The paper presents the first stage of modeling, which includes design and selection of grooves scheme with used the finite element method. The last six passes were modeled. The rolling scheme obtained from the modeling in the next stage is simulated by FEM to obtain thermomechanical parameters of the process. Then, temperature, strain and strain rate distributions in bar cross-sections, rolling time and inter-pass time will be used as input data for modeling by FCA.

Abstract: We have developed a growth procedure for increasing the number of stacked layers of InAs quantum dots (QDs) on an InP(311)B substrate that is resistant to defects and dislocations. In this work, we also developed a modulated stacking structure consisting of various size QDs for electroluminescence (EL). This promotes broad-band emission because each QD-distributed wide range can emit a different wavelength. The EL spectrum of this sample was measured with pulsed current injection. There was a strong emission from the ground state at approximately 1524 nm which is suitable for fiber-optic communications, with an injection current of 100 mA at room temperature. The full width at half maximum was 213 nm. Modulated stacking using this strain-compensation technique is thus a useful way to expand the gain wavelength.

Abstract: A new muffler is designed to improve the noise emission of a 40HP Roots blower. The structural design of the muffler is discussed, including using glassfiber blankets of different densities for high-frequency noise, and multiple resonant chambers and microperforated plates for low-frequency noise. The noise of the discharged air stream of the Roots blower is significantly reduced from for 111 dBA to 78 dBA after installing the new muffler. Acoustic simulation on the muffler is performed and design optimization based on transmission loss is conducted using Taguchi method. ANOVA analysis, S/N ratios, and S/N curves are used to acquire the optimal combination of design factors.

Abstract: In this paper we present a system for aircraft structural health monitoring based on artificial immune systems with negative selection. Inspired by a biological process, the principle of discrimination proper/non-proper, identifies and characterizes the signs of structural failure. The main application of this method is to assist in the inspection of aircraft structures, to detect and characterize flaws and decision making in order to avoid disasters. We proposed a model of an aluminum beam to perform the tests of the method. The results obtained by this method are excellent, showing robustness and accuracy.