Papers by Keyword: Experimental Modeling

Abstract: In order to develop a compact and lightweight controllable damper for space truss structures vibration suppression, a novel double-piston magnetorheological (MR) damper is proposed. Working principle of this damper has been analyzed. One prototype damper have been designed and fabricated according to the analysis results. A series of experiments have been performed to get this prototype damper's dynamical properties. Hyperbolic tangent model have been used to describe damper's nonlinear hysteresis. After model optimization using the nonlinear least squares method, the relationship between damper force and drive currents have been acquired under different excitation conditions. Comparison between the reconstructed results and testing data indicates that the optimized model shows enough accuracy to not only present the experimental data, but also forecast the hysteretic properties of this damper.

Abstract: District heating process is a complicated dynamic and thermal nonlinear system. For controlling it the system model should be found firstly. Through the research and analysis of the knowledge about heating system, this paper on the basis of mechanism model, researched the establishment of experimental models. Firstly by measuring the response data, the model parameter identification of the heating process can be made to got the heating determining part model, then random part of the system model can be described by the method of Autoregressive Integrated Moving Average Model. Finally using the MATLAB to simulate and make the model step response curve analysis. Simulation results show the model is effective and verified.

Abstract: Deformation process and strength of rock environment is significantly influenced by a presence of discontinuity planes. The paper deals with experimental modeling of underground structures in such a rock environment. Parametric analysis presents results from twin circular tunnels simulated in a scale model. The cases with and without zone of dislocations in between the tunnels were observed. Another variable factor studied was the distance between tunnels. The relation between model surface displacement and excavated length of the tunnel, which was monitored during the simulations, was used for mutual comparison of individual cases.

Abstract: A finite element reinforced concrete model has been analyzed by the author with ANSYS 9 finite element program for both unstrengthened and CFRP-strengthened beams using concrete element model 25x25x25mm and discrete and smeared steel distribution with openings exist. The CFRP has been modeled using Solid46 element, which has orthotropic properties. The deflection results have been compared with an experimental and other finite element model which are performed by Mohamed [4], in which using 100x42.5x42.5 mm concrete element, smeared steel distribution with the same opening sizes, and modeling CFRP with ANSYS 5 finite element program using Link10 element which has a uniaxial properties. These results show that the author's model is much better than the Mohamed's [4] model comparing with the experimental one. A parametric study has been done on the proposed model for obtaining the maximum strains values for concrete and steel at failure loads, for different opening sizes and comparing them with the experimental one. This study show a good agreement between the proposed and experimental model results for strains values which indicate the efficiency of the proposed model for analyzing the unstrengthend and strengthened reinforced concrete beams.

Abstract: In order to infiltrate the molten aluminum alloy to the reinforcement preform by low pressure in casting process and acquire the high performance composites with high density, the effect of the ultrasonic vibration on the infiltration was investigated by model experiments using clear solution and glass or aluminum borate preform, which is correspond to a molten matrix and reinforcement, respectively. Ultrasonic vibration improves the wettability of liquid polyester resin on glass plate, dramatically. The final infiltration height and infiltration speed of liquid polyester resin in glass capillary were improved by the ultrasonic vibration. Furthermore, the infiltration speed of water to aluminum borate preform accelerated by ultrasonic vibration. This effect was more remarkable, when the infiltration height is lower or infiltration time is shorter. In actual, the molten aluminum alloy infiltrate to SiC preform using ultrasonic vibration easily and acquire the high dense composites without pores.