Applied Mechanics and Materials Vols. 138-139

Abstract: Simulating motion process of incompact soil. Monitoring evolution process of average contact force and unbalance force between particles during moving; Recording microscopic parameters and its changing processes, incliding spatial locations, translational rate and rotation rate of specific particle during the moving. Simulation results properly reproduced the whole process of it along slope, which include the starting, moving, piling up. Simulation results indicate that: Process of its motion manifest the macro space position changes, as well as, are the change process about contact stress, unbalance force within the inter particle and single particle movement mechanics etc. Size of average contact force reflects close degree between particles, fluctuation extent of microscopic parameter and levels of interaction between particles. Microscopic parameters of movement process can be used in the theoretic modeling analysis of complex movement of the incompact soil.

Abstract: Based on the subroutine VUMAT, user-defined material model in the nonlinear finite element software ABAQUS/EXPLICIT, a nonlinear viscoelastic constitutive model is developed. The validify of the subroutine has been proven through the standard uniaxial tensile model. The shortage of finite element softwares which only have linear viscoelastic constitutive model is remedied. This paper presents the process of developing a material constitutive model and some useful technology. It can be referred for extending the material constitutive model in finite element softwares.

Abstract: In the present work steady air injection upstream of the leading edge was used in a centrifugal compressor, Whose preliminary design of compressor injection systems can be modeled by a geometrical relationship between user-specified yaw angle and resulting blade incidence angle based on simple velocity triangles, the error between the best yaw angle obtained from this relationship and that obtained from numerical simulation is less than 3%. To reveal the mechanism, steady numerical simulations were performed on high pressure ratio centrifugal compressor rotor operated with a rotor tip speed of 586 m/s. Parametric studies of the injection yaw angle was performed to determine the configuration that provide the best steady results for the compression systems studied in this work. The injectors were placed at short distance (ten percent of the inlet tip radius upstream of the compressor face) the objective of this was to achieve maximum control over the leading edge flow by varying individual injection parameters. The injection angle, α, was fifteen while the yaw angle, β, was parametrically varied. The results show that at design speed (n= 50 000 r/min) with injection flow rate equal to 3% of the main flow rate and 25 degree air injection yaw angle can lower the mass flow rate at stall for approximately 7.5%.

Abstract: Water damage in asphalt pavement is related to the interaction between cracks and hydrodynamic pressures caused by the vehicle. A 3D finite element model of the hydraulic crack in asphalt pavement was built to analyze the crack propagation character under vehicle load. The influence of asphalt pavement structure parameters, vehicle speed and crack geometric parameters of hydraulic crack were discussed. Then the differences, between aqueous cracks and cracks without water, were compared. The research results had the guiding meaning for anti-water damage design of asphalt pavement.

Abstract: A J-lay crane barge named Double-8000, the two cranes of which have the lifting capacity of up to 8000t, is about to be constructed by Offshore Oil Engineering Co., Ltd. (COOEC) in order to meet the requirements of oil and gas development in South China Sea. This paper presents the overall structure design of the J-lay system and corresponding method for strength calculation. The hardware and software for the J-lay control system are also developed. The model test on such a designed J-lay system along with its control system is investigated by applying the similarity theory and the hybrid model test method. A specially designed platform simulating the motion of the crane barge in 6 degree-of-freedom (6-DOF) in different sea conditions is used for the model testing in order to get the results of the influence of the crane motion on the performance of the J-lay system. The model tests verify the functionality and safety performance of the system. The results show that the test data are in good agreement with the numerical simulation. It can be seen that the J-lay system can meet the challenging requirements of Double-8000 for pipeline laying in waters deep to 3000m in South China Sea.

Abstract: Seismic wave contain more information about the sediments. The seismic attributes has some relationship with the coal seam thickness. Through analysis of the wedge-shaped coal seam’s seismic attributes, when the seam thickness is less than the tuning thickness, there is proportional relationship between the amplitude value and seam thickness; while the apparent time difference between the wave peak and trough is not sensitive. When the coal seam thickness is above the tuning thickness, the conclusion is opposite. As a result, it’s difficult to predict the coal seam thickness only by using one single attribute. Therefore, we use the nonlinear-regression method to analyze the relationship between the seam thickness and both attributes, and get a method to predict the coal seam thickness. With the method we predict the coal seam thickness in a coal mine and get a perfect result.

Abstract: This paper presents a delay independent algorithm for bilateral control system which necessary uses for achieving in teleoperation. The system uses a state space expression to implement error dynamic equation with a tow channel structure. Then, several linearity matrix inequations (LMI) called stabilization theorem are constructed. Lyaponov function method is used to prove the stabilization theorem. Experimental results show that our approach is valid and has encouraging stabilization performance.

Abstract: In this paper, the double filter cylinder of the compact containment sump strainer innuclear power station was adopted as the research object. The impact and transmission mechanicalexperiments were carried out to investigate the material and structural properties in the event ofearthquake and LOCA (Loss-of-Coolant Accident). Furthermore, the modal analysis and the stresscalculations were conducted in LOCA condition to test the validity of the filter cylinder. The researchresults could provide the basis for designing the double filter cylinder of the compact containmentsump strainers.

Abstract: Using a weighed decomposition of the stiffness matrix and the weighed generalized inverse theory, a reanalysis method is presented for the topological modification of plane structures, and a set of formulae of elementary topology change are obtained. These formulae are explicit one and using them one can reanalyze the modified structures in topological optimal design. Finally an example is given to verify the valid of this method.

Abstract: Based on the middle body frame of a Half-integral bus which a bus manufacturer mainly produces in China, this paper discusses analyses and improvements for rollover security of the bus middle body frame with TRIZ methodology and TRIZ tools. On the basis of forming mechanism of bus rollover, a breakthrough point has been found from cause and effect relationship and function achievements aspect; some customized measures are therefore proposed. It focuses on the stiffness design of side pillars and the strength enhancement of soldering joints. Applying CAE analysis based on Ls-dyna, the results show that the deformation and deformation mode of the bus middle body frame have been greatly improved during bus rollover, which fulfills the requirements of the force of ECE R66 Rollover Security Regulations and validates the correctness of suggested measures.