Papers by Keyword: Theoretical Analysis

Abstract: The burst strength is the key parameter to the design of glass-fibre reinforced composite (GFRC) pipes with good performance and security. In this paper, the burst strength and the optimized winding angle of the GFRC pipes are derived by the theoretical analysis, experiment and simulation considering the progressive damage. The effects of the winding angle on the burst strength and failure modes are fully discussed. The results show that, the burst strengths obtained by the proposed theoretical formulas and simulation agree well with the experiment results. There is a critical winding angle for the GFRC pipes demarcating the burst modes of axial burst or circular burst. With the increase of the diameter, the critical winding angle decreases, but never less than 55^° . With the increase of the winding angle, the burst strength firstly increases, and then decreases. The winding angle of the GFRC pipes should be optimized between 55^° and 60^° to derive the best burst strength.

Abstract: Development of environment-friendly materials to improve the safety and fuel efficiency of automobiles has attracted great research attention with regards to the automobile industry in recent years. With increase in demand for technological developments to improve performance and efficiency, an increased number of researches are being performed concerning the use of advanced high-strength steel in parts manufactured by means of the hot-press forming process. Furthermore, research concerning the improvement in fuel efficiency through additional weight reduction using tailor-welded blanks (TWBs) and partial quenching (PQ) has gained popularity in the automobile industry in recent times. Many car components are, nowadays, being fabricated using different materials to improve collision toughness and safety in the event of a car crash. However, no standard has yet been established to evaluate the replacement of automobile parts, and such a standard must account for mechanical properties of the material under tensile and flexural loadings. A car crash test was conducted at the Insurance Institute for Highway Safety (IIHS) to evaluate automobile safety. However, collision-toughness evaluation of each car component is expensive and difficult to realize. In this study, drop tests were simulated, and collision characteristics of the center-pillar were correspondingly evaluated. Values of fracture toughness were compared in accordance with center-pillar types for evaluating collision-test conditions.

Abstract: Technology of CO₂ Geologic Storage (CGS) especially its possible developments is helpful for improvements in reducing greenhouse gases and alleviating the greenhouse effect, which are necessary at global scale due to rising demand for fossil energy. The theory of deformation due to liquid injection was learned. A test on laboratory scale which injects water into compacted sand covered by low permeability clay showed the land uplift phenomenon. Some further discussions of the land uplift with different injection quantity was studied.

Abstract: In order to achieve different response indifferent moment of fuel Injection Solenoid, a driving mode of Peak&Hold is generally applied to electronic control fuel injection system of the diesel engine. The theoretical analysis of high speed response and duplicate supply drive circuit based on the energy recovery is made, and a theoretical guidance for optimization design is presented. According to an electronic unit pump developed by ourselves, the optimization design of drive circuit for the fuel injection system is done. The results showed that during the process of injection, the time of current of solenoid valve form 0 to 20A is 224, and the turn-off time is 120which is a little longer than that of the high speed circuit based on the avalanche. And the turn-off time is met the requirement of control precision. With many advantages, such as energy saving and heat reducing, the high speed response and duplicate supply drive circuit based on the energy recovery will become a good choice in electronic control fuel injection system.

Abstract: In this work, six asymmetric compound parabolic concentrators (ACPC) were designed for concentrating radiation on all-glass evacuated solar tubes (EST). The ACPCs are required to be horizontally oriented in the east-west direction and to collect direct sunlight for at least 6 hrs in any day of a year. The angular dependence of optical efficiency of six ACPCs, identical in the height of both reflectors after the higher reflector being truncated, was investigated by ray-tracing method, and the annual radiation on EST concentrated by ACPCs was estimated based on solar geometry and monthly horizontally radiation. Results shows that the ACPC designed based on “hat shaped” virtual absorber with a V-groove at the bottom of reflectors is the best in terms of the optical efficiency averaged over the acceptance angle, followed by the one designed based on “hat-shaped” absorber without a V-groove at the bottom, and the one designed based on the cover tube of EST is the worst. However, from the point of annual radiation on EST, the ACPC designed based on the cover tube is the best solution, followed by the one designed based on “ice-cream shaped” absorber and the one designed based on “hat shaped” absorber is the worst due to the smallest geometric concentration factor.

Abstract: In this work, the angular dependence of optical losses through gaps, constructed by truncating reflectors near the absorbers, of CPCs with one-sided flat absorber was presented, and the annul radiation loss through gaps of east-west aligned CPCs is theoretically investigated. Results show that the optical losses are mainly resulted from direct radiation loss through gaps due to direct irradiation on gaps, and the loss of radiation that arrive on gaps from reflectors after multiple reflections is considerable small and can be neglected in solar calculations especially for truncated CPCs. Results also show that the annual direct radiation loss is dependent on geometric parameters of CPCs but seems independent on solar resource in sites where CPCs are used, and the annual radiation loss of full CPCs oriented in east-west direction with the tilt-angle of aperture being yearly fixed is almost identical to average optical loss of the CPC over its acceptance angle.

Abstract: So far, thermal shock theories have not been well verified in refractories. This paper compared hypothesis and failure mechanism of two typical thermal shock theories, analyzed the applications of two typical theories in refractories from working environment, failure process and microstructure differences. And thinks that the critical stress fracture theory is suitable for nearly ideal brittle refractory with ceramic bond and used in thermal shock extremely harsh environment; thermal shock damage theory suites to evaluate multiple loops thermal shock. Analyzed the factors influencing the thermal shock parameters, and discussed Ways to improve the thermal shock resistance of refractories from destructive force and resistive force of refractories. Conclusions are that choosing small swelling expansion rate and high thermal conductivity material, reducing the micro stress concentration and adding flexible phase, these three methods can be used to make refractories with good resistance to thermal shock.

Abstract: This paper presents a new design scheme about the bearing transmission components based on compliant parallel spring mechanism, which is applied to small and medium scale impulse plate flowmeters. The detection components can be effectively carried with a more accurate trace of displacement in the horizontal direction. The mechanism design has advantages of no relative motion and friction between the structure components, and is well adapted over the traditional bearing components, based on the principle of compliant parallel spring mechanism. Thus, the measure precision of impulse plate flowmeter and working reliability are effectively improved. Firstly, the characteristics of displacement, strength and natural frequency are analyzed theoretically, and then the simulation of static strength, modal and fatigue are performed by the CAE software. The rationality and feasibility of this design scheme are further verified by the simulation results, which has certain guiding significance for the design of the actual product.

Abstract: A new type buckling restrained brace ensuring to work under different levels of earthquakes is analyzed in this paper. The brace is simplified by LINK elements of SAP2000. The skeleton curve of the mode is clarified. Three specimens with different slot widths are designed to evaluate the simplified model used in the software SAP2000. The evaluation work is accomplished through the software ABAQUS. The force mechanism, the hysteretic model and proposed reasonable scopes of slot widths are grasped. The numerical simulation work proves that the new type buckling restrained brace performs excellently.

Abstract: The environmental deterioration of the subway station and the safety of the personnel evacuation under platform train fire are researched. The critical fire danger condition is proposed and the time calculation method of evacuation is determined. A platform train fire in a subway station is simulated by the Fire Dynamics Simulator software. Then the available egress time can be got by analyzing the fire temperature and smoke concentration change with time. At the same time, the required egress time is studied through theoretical analysis and computer simulation by software Building Exodus. The results showed that smoke exhaust rate is very important to the smoke control under platform train fire. And the stair evacuation ability is the key to the whole evacuation.