Applied Mechanics and Materials Vols. 34-35

Abstract: For the measured deformation time series of concrete engineering, linear and nonlinear chaotic prediction methods are represented for the autogenously volume deformation of concrete on basis of phase space reconstruction. Thus，the chaotic analytic method is set up for the prediction of the measured deformation time series of concrete engineering. At first，the autogenously volume deformation of RCC mixed with MgO are simply presented. Then，for the measured convergent deformation time series of RCC mixed with MgO，the interpolation method is adopted and an equal interval deformation time series is obtained. The results show that the largest Lyapunov exponent is 0.02 based on phase space reconstruction. Finally，it is separately predicted by the method of equidistance in near neighbor and that of the largest Lyapunov exponent prediction，and the predicted deformation values are ideal compared with the measured deformation values.

Abstract: Finite element (FE) method is an efficient and power tool, and is adopted to analyze dynamic response of printed circuit board (PCB) assembly. First, FE model of PCB assembly was established. Second, the dynamic behaviors of ball gird array (BGA) lead-free solder joint were obtained when the PCB assembly was subjected to a half-sine acceleration pulse. Results show that the maximum tensile stresses occur at solder joints located at the four outermost corners of BGA and solder joints at outermost corners are the most vulnerable to crack. In addition, it can be found during FE analysis that the solder joint reliability can be enhanced as the PCB damping increases and input acceleration level reduces.

Abstract: In order to achieve active health monitoring of seven-wire steel strands, single magnetostrictive transducer with two-layer coil is developed and applied for the excitation and reception of ultrasonic longitudinal guided waves simultaneously. The transducer can be conveniently fixed at any single one position on the helical surface of these structures. The inner and outer layers of its coil are used for excitation and reception respectively with the help of same axisymmetric permanent magnets. Experimental results show that chosen ultrasonic longitudinal guided wave mode, L(0,1) at 140kHz, can be excited and received with high signal-to-noise ratio in steel strands by using the developed magnetostrictive transducer. Furthermore, to identify the performance of the transducer, the detection of an artificial defect is also conducted.

Abstract: The relationship between concrete performance and influence factors is uncertain and nonlinear. Accordingly, present BP neural network and virtual samples are presented to predict concrete performance in this paper. At first neural network and matters which need attention are introduced, And frost resistance forecasting model and impermeability model are built up, which are three-tier BP neural network of 6-13-2,4-9-1.The results show that the predicted values are ideal, and artificial neural network as one of the methods to forecast performance of concrete is appropriate.

Abstract: Rigid rotor roller bearing system displays complicated nonlinear dynamic behavior due to nonlinear Hertzian force of bearing. Nonlinear bearing forces of roller bearing and dynamic equations of rotor bearing system are established. The bifurcation and stability of the periodic motion of the system in radial clearance-rotating speed and ellipticity-rotating speed parametric domains are studied by use of continuation-shooting algorithm for periodic solutions of nonlinear non-autonomous dynamics system. Results show that the parameters of rotor bearing system should be designed carefully in order to obtain period-1 motion.

Abstract: Removed due to plagiarism. The original research was published as: MODELING OF CORNER ECHO IN UT INSPECTION COMBINING BULK AND HEAD WAVES EFFECT <http://apps.webofknowledge.com/full_record.doproduct=UA&search_mode=GeneralSearch&qid=2&SID=U2SJlTPsegzt99T6d6T&page=1&doc=8> By: Mahaut, S.; Huet, G.; Darmon, M. Edited by: Thompson, DO; Chimenti, DE Conference: 35th Annual Review of Progress in Quantitative Nondestructive Evaluation Location: Univ Chicago, Chicago, IL Date: JUL 20-25, 2008

Abstract: This paper presents a novel 3-D topography model for micro-manufacturing process simulations, which uses unit vector of the parametric surface as an important parameter to achieve the surface evolution algorithm. According to various physical models of given fabrications, it can be applied to simulations of isotropic/anisotropic etching, deposition, and other processes with surface evolution direction dependence. The simulation results of this model are 3-D visible of variable perspective. Furthermore, simplification is introduced in some special case to reduce memory requirement and calculation time. Some isotropic etching simulations are performed as examples, and the results indicate the accurate simulated surface.

Abstract: This paper describes indoor mobile robot covering path to avoid obstacle based on behavior fuzzy controller. The robot measures the distance to obstacle with ultrasonic sensors and infrared range sensors, and the distance is the input parameter of the behavior-based fuzzy controller. The behavior architecture has three levels behaviors: emergency behavior, obstacle avoidance behavior, and task oriented behavior. The task oriented behavior is the highest level behavior, and has two subtasks: wall following and path covering. The middle level behavior is obstacle avoidance. The lowest level is an emergency behavior, which is the highest priority behavior. The simulation result demonstrates that each behavior works correctly.

Abstract: This paper presents a novel fault diagnosis method which overcomes the shortcomings of traditional approaches. It uses dynamic fault tree model for reliability analysis. All minimal cut sequences are generated via a new modular method, while the diagnostic importance factor (DIF) of components and minimal cut sequences are calculated using discrete-time Bayesian network. Also, we introduce the cost of diagnostic importance factor (CDIF) for components to evaluate the influences of the test costs, and combine it with minimal cut sequences’ DIF to determine the order of the system diagnosis. Finally, an example is given to demonstrate the effectiveness of this method.

Abstract: A new technology of piezoelectric self-adaptive micro electrical discharge machining has been developed in this paper according to the characteristics of micro-EDM. Its working principle and the discharge characteristics are introduced, and it has been proved that the new technology can achieve micro machining. Using piezoelectric actuator as micro-feed mechanism, this new technology is simple in structure and can improve the discharging gap effectively. The discharge frequency and effective pulse utilization rate of the power supply is enhanced in machining. Experimental results show that this new technology can achieve good results.