Applied Mechanics and Materials Vols. 148-149

Abstract: This paper presents a variation of effective stress parameter with matric suction for unsaturated soils using a comprehensive data set of suctioned-controlled shear tests under drying and wetting processes. The effective stress parameter is determined by assuming that the slope of the critical state line in the plane of deviator stress against mean effective stress is independent of matric suction. This study shows a different in relationship between the effective stress parameter and matric suction for drying and wetting processes. The values of effective stress parameter obtained from the experiments were compared with those obtained from the expressions proposed in literature.

Abstract: Under the context of airplane deicing, this paper aims to do a research on the unrelated parallel scheduling of service resources with flexible time window. To deal with more tasks, minimizing delay time is chosen to be the objective of the mathematical model and a modified ant colony algorithm is given. With full consideration of the practical problem and constraints, update policy of pheromone and settings of heuristic factors are suggested. The feasibility and rationality are proved by a simulation example. The modified ant colony algorithm outperforms FIFO method and could be well applied in the unrelated parallel scheduling issues with flexible time window.

Abstract: The random distribution packing models of particles in the binder of solid propellant were generated based on the Molecular Dynamics method. The generated packing models were then analyzed by finite element method combined with the analytical method. A cohesive interface model was incorporated to capture the debonding process taking place along particles binder interface. The results show that the FEM analyses with cohesive interface can predict the complex heterogeneous stress and strain fields and the progress of debonding of particles from binder. Particles interaction significantly influences the interfacial damage evolution of propellant.

Abstract: According to the complex damping theory, the formula to calculate equivalent damping ratio of composite structures is derived from damping stiffness matrix by dynamic analysis. The finite element model of a steam turbine foundation is established. The equivalent viscous damping ratio is calculated from natural frequencies, modes and structural stiffness matrix. Due to the vertical stiffness of spring vibration isolator is larger than lateral stiffness of concrete structure, most of free vibration modes of the foundation are movements of concrete structure. Therefore, the equivalent mode damping ratio is close to the one of concrete structure. The dynamic response is overestimated, if the equivalent mode damping ratio is derived from the average of spring vibration isolator and concrete structural ones.

Abstract: The traditional artificial mode of engineering change implementing in aero-engine assembly field often results in difficulties of the process control. To solve this problem, this paper firstly puts forward an aero-engine assembly field configuration relationship model (AACRM) based on the configuration data structure and correlation coordination relationship between configuration items, then analyzes the structure of engineering change document and its implementation process in assembly field. Lastly, assembly field engineering change implementing process model (AEIPM) is established based on Petri nets modeling method, which constructs the implementing and confirming process of engineering change from a product level to a step level and then from a step level to a product level.

Abstract: According to the characteristics of the laboratory, for the condition of using air conditioning that is falling to the ground pattern to assist radiator to heat, use CFD to simulate the airflow organization and thermal environment in laboratory. Meanwhile combine with the indoor relevant measured parameters, analyze distribution characteristics and finally evaluate the thermal comfort in laboratory in winter.

Abstract: Because the wavelet transform can characterize the local signals in time and frequency domain, in the coal mine’s sound signals’ process, an audio signal processing based on wavelet analysis is proposed, the audio signal P wave is isolated and determined by wavelet transform, at the same time, the earthquake source can be located. Through the research of the mine AE signal’s activity patterns, the sound monitoring technology to forecast the mine power disaster is achieved.

Abstract: The paper shows the comparison of energy and exergy analysis of thermal power plants based on advanced steam parameters in China climatic conditions. The research contains coal-based thermal power plants using sub-critical, super-critical, and ultra-supercritical steam conditions. The design configurations of 500 MW unit size were considered. The research contains the effect of condenser pressure on plant and exergy efficiency. The effect of high grade coal on performance parameters as compared to typical China low grade coal was also studied. The major exergy loss took place in coal combustion followed by the steam generator. Due to condenser pressure limitation, the maximum possible overall energy efficiency was found to be about 44.4% with the ultra-supercritical power plant. Installing coal-based thermal power plants based on advanced steam parameters in China will be a prospective option aiding energy self-sufficiency.

Abstract: In the paper, it is to describe the performance of the vertical ground heat exchangers (GHE) in different areas of China. The energy consumption of ground source heat pump (GSHP) system is based on the instantaneous fluid temperature at the heat pump inlet. This temperature defines the GSHP coefficient of performance and hence the electricity consumption required in order to fulfill the energy demands of the building. A mathematical model for simulation of vertical ground heat exchanger system is built based on long time-step theory. The design methodology is based on a simulation that predicts the temperature response of the ground heat exchanger to hourly heating and cooling loads demand in 20 years. This paper presents GSHP system can achieve energy performance in buildings that heating and cooling loads all the year round in different areas.

Abstract: It had been studied that thermal deformation properties of super-alloy Inconel690(IN690) by thermal simulation on Gleeble 3800 Simulator, which the ranges of temperature was 1000～1200°Cand strain rates was 1.0～80/s. According to the experiment data, the critical conditions of super-alloy Inconel690 had been researched by strain hardening rate. Zener-Hollomn parameters (Z) had been introduced into establish the critical conditions of dynamic recrystallization, such as critical strain and critical stress and peak strain. The results showed that the critical strain model which established using strain hardening rate was in good agreement with that of Sellar’s model.