Applied Mechanics and Materials Vol. 187

Abstract: The velocity signal of the flow field in Impinging Stream Mixer (ISM) was measured with Laser Doppler Anemometer. A de-noising method for velocity signal in ISM based on wavelet threshold was used. It is obtained that the attractor of the system possess infinite self-similar nested structure by comparing the strange attractor before and after de-noising, which is based on phase space reconstruction theory. It is shown that K entropy and the largest Lypunov exponents have the similar tendency in spatial distribution through scientific computation, however, the stratification of K entropy is more obvious. The value of K entropy and the largest Lypunov exponents are both positive, proving that the system is chaotic. The results indicate that K entropy and Lyapunov exponents can be increased by improving the rotating speed, the disorder and unpredictability of chaos system will increase homogeneously, so as to promote the micro-mixing and improve work efficiency

Abstract: For studying dynamic characteristics of fluid filled pipe under hydraulic excitation force generated actively by a new developed vibration exciter, at first a computer code based on the method of characteristics (MOC) was developed. Then the excitation force calculated by MOC was applied to the corresponding nodes of finite element of pipe, by using Newmark’s method, the dynamic response at every cross section of pipe was obtained. The numerical simulations show that a simple harmonic motion arises at every cross section of the pipe, and the lateral vibration amplitude of every node along the pipe increases as the rising excitation force. In addition, measured data were compared with numerical simulation, which were basically consistent with each other.

Abstract: It is difficult to build a precise mathematical model for complex ball and plate system and many intelligent algorithms’ programming are larger, so we make use of the non-linear PID controller to control actual system and realize the point to point control and circular trajectory control of the ball. The experiment results show that the control method of non-linear PID could ensure the movement accuracy of the ball, achieve the performance of control process, and have better control effect than traditional PID.

Abstract: Gearbox is a key part and is more easily over loaded and it has a high failure rate in MW-class wind turbine. It is necessary to analyze, predict and optimize its static/dynamical behavior. It presents the performance of one type wind turbine gearbox and the static analysis results of the housing, spline and gear pairs of the wind turbine gearbox are obtained using finite element method. The natural frequency and modal shape of the gearbox are analyzed. The modification data of the flank shape for each class tooth alignment and tooth profiles are obtained from the analysis. The related data on the strength and stiffness of all the parts in wind turbine gearbox are provided. It lays a foundation for the reliability assessment and optimization design of wind turbine gearbox.

Abstract: A vehicle based on automatic route identification technology by using modulated infrared photoelectric sensors was introduced. Circuits for path detecting , motor drive, speed sensor and servo drive were designed. And the controlling strategy was introduced. At last, the assembled model car could run along the black line stably and fast.

Abstract: The study of low frequency, small size transducer was an important aspect for the development of the underwater acoustic transducer. The Class Ⅳ flextensional transducer was a typical low frequency, high-power and small size transducer. For decreasing its resonant frequency in the case of small size, a flextensional transducer with slotted shell was analyzed using finite element software ANSYS. A comparison between the flextensioanl transducer with slotted shell and the Class Ⅳ flextensional transducer was made. The maximum size of the shell is 200mm. The transmitting voltage response of the transducer reaches to 131dB with resonant frequency 600Hz in water. The transducer could radiate at low frequency with small size of the shell.

Abstract: Plain wall system is highly suitable to be used with reinforced concrete as its building material. Concrete vertical walls may serve both architecturally partitions and structurally to carry gravity and lateral loading. Moment transfer of joint is an important aspect for proper structurally functioning of plain wall system. Hence, the aim of this study is to investigate experimentally the effect of reinforcement details in the wall on bending capacity for support stiffness in plain wall system in Malaysia. A total of six wall specimens were tested. Three of this specimens consisted single layer of rebar while another three specimen consisted of double layer of rebar. The size of the plain wall’s specimens is 1000mm in length, 1080mm in width, 1000mm in height and 80mm in thickness. The average concrete strength was 23.49MPa with Grade 30N/mm2 and the average yield strength of R5 bar was 817MPa. The bending capacity at failure for single layered of rebar in wall for specimen 1, 2 and 3 were found to be 3.59kNm, 3.81kNm and 3.15kNm, respectively. The bending capacity at failure for double layered of rebar in wall for specimen 1, 2 and 3 were 5.50kNm, 6.31kNm and 7.00kNm, respectively. Based on the results, specimens consisted of double layered of rebar in wall is found to provide higher bending capacity to the joint of plain wall system in the range from 56.25% to 98.86% compared with single layered of rebar in wall.

Abstract: Vibration analysis is widely used for gear faults diagnosis. A gear vibration monitoring system based on virtual instrument developing platform LabVIEW and vibration analysis technology is developed and introduced in this paper. It satisfies the requirements of machinery condition monitoring and supports function expansion. Online and offline monitoring of gear running states can be realized though this system in both time domain, frequency domain and joint time –frequency domain. Experiments showed that this gear vibration monitoring system can be widely employed in gearbox. System not only guarantees the accuracy of the test results but also provides a friendly user interface for users’ easy operation.

Abstract: The basic configuration and control method of the humanoid robot SCUT-I are presented. SCUT-I, developed by the Robot and Intelligent Software Laboratory in South China University of Technology, 58.2 centimeter tall and 3.9 Kg weight with 21 degree of freedom (DoF), was designed to be humanlike including two legs, two arms, a trunk and a head. The mechanical design, hardware description, sensor fusion and motion control schemes of SCUT-I are represented, and a kind of dynamical walking control schemes based on linear inverted pendulum model (LIPM) and attitude sensor feedback control is proposed.

Abstract: On the basis of analyzing all forces on the self-supported vertical vessels, the superposition method in mechanics of materials and a MATLAB program are used to calculate the maximum wind bending moments of the high vertical vessels caused by both weight and linear distributed wind pressure. The results show that the effect of weight to wind bending moments of the heavy weight high columns can not be ignored. And a special formulation for calculating the maximum wind bending moment is deduced which can be directly used for strength and/or stability calculations.