Advanced Materials Research Vols. 532-533

Abstract: To meet the given requirements of rigidity and strength of the system and make the system for minimum weight, optimization design of three bar system is carried out by the finite element software ANSYS, The finite element model of truss system is established, loaded and solved and the structure system is optimized using its optimal function module. The truss system optimal combination is given and these can provide a valuable theory basis for similar actual engineering design.

Abstract: A method to find the optimized parameter values of passive dynamic walking biped is presented. The effects of biped physical parameters on the stability property of passive gaits are studied by simulation experiments. The chosen parameters include the mass distribution, length of leg and slope angle. The stability property of passive walking limit cycles is used as criterion of optimization calculation, including the orbital stability described by eigen-values of linearized Poincaré map and the global property described by size of attraction region. The simulation results show how the stability of limit cycle varies when physical parameters of the passive biped change. The work is useful to explore the inherent property of passive dynamic walking and can be used as an important instruction in the mechanical design of biped robots based on principle of passive dynamic walking.

Abstract: The contact state of water-lubricated thrust bearing has been researched using FEM (Finite Element Method), the changes of contact pressure, deformation, temperature and etc have been analyzed and the bearing’s tribological properties under low-speed and heavy-load situation has been revealed, which are benefit in improving the bearing design, increasing the bearing’s durability and safety reliability. The results show that the max comprehensive stress, the max contact pressure and the max vertical displacement appear on the platform of the thrust pad; the temperature of one increases along with the speed and axial load increasing, and the highest temperature appears on the platform of the thrust pad.

Abstract: To inspect the surface quality of steel bar, we designed an automatic system including linear camera and laser. Through the comparison among kinds of cameras, we select linear CCD to our system. The laser is also chosen by us with its high luminance and performance. Through a series of computation, we select the appropriate camera lens to our device. At last, we draw the whole detection system. This device has been used well and provides a good foundation for prospective image processing.

Abstract: Visual sensors can be used for monitoring the welding seam and seam tracking, but it is difficult to acquire the deviations between the laser beam spot and the weld seam from the images because of the strong disturbances caused by spatters and plume. An extraction method was developed to detect the deviations between the laser beam spot and the weld seam during high power fiber laser welding. Laser welding experimental results showed that the deviations could be detected accurately, and the proposed method can be used to monitor the seam tracking status.

Abstract: An integrated system to measure mechanical functions of material or structure is introduced. This system is able to provide more detection methods and experiment environments. And it can discover the characteristics and mechanisms of damnification and breakage in materials, considering the effects of loading and environments. Material functions were analyzed in many aspects, including loading, strain, light, sound, temperature and infrared to ensure the safety of materials and configuration of unmanned plane. Current study has laid a foundation for realizing optimal design of unmanned plane. In this paper, theory, components, and function of the system were discussed, as well as signal acquisition and analysis.

Abstract: The lumped mass on the cylindrical pipe affects the natural frequency of the cylindrical pipe. The first-three order natural frequencies and vibration modes of the cylindrical pipe with different lumped masses are analyzed by the bending vibration theory and finite element analysis, respectively. The results with different lumped masses are obtained by experiments. As shown in the results, the natural frequencies of the cylindrical pipe with lumped mass are lower than those without lumped mass. The greater the lumped mass is, the smaller the natural frequencies of the pipe are.

Abstract: The response surface method was proposed as a collection of statistical and mathematical techniques that are useful for modeling and analyzing a system which is influenced by several input variables. This method gives an explicit approximation of the implicit limit state function of the structure through a number of deterministic structural analyses. However, the position of the experimental points is very important to improve the accuracy of the evaluation of failure probability. In the paper, the experimental points are obtained by using Givens transformation in such way these experimental points nearly close to limit state function. A Numerical example is presented to demonstrate the improved accuracy and computational efficiency of the proposed method compared to the classical response surface method. As seen from the result of the example, the proposed method leads to a better approximation of the limit state function over a large region of the design space, and the number of experimental points using the proposed method is less than that of classical response surface method.

Abstract: To study the aerodynamic characteristics of strayed cable under wind and rain, with the object of the Zhijiang bridge, pressure experiments on the 2- and 3-dimensional models of stay cables in wind tunnel are made. Mean and fluctuating wind-pressure coefficients with 2 kinds of surface morphology under different wind direction angle are obtained. The results show that the rivulet position will greatly influence the distribution of pressure coefficients on the cable surface, and the separation point of the flow nearby the rivulet will be changed obviously. Aerodynamic coefficients will be changed when the rivulet be in a certain position, then the rain-wind-induced vibration will occur .The experimental results will be the guidance for the wind-resistant design and the safe production of the long-span cable-stayed bridges.

Abstract: In order to improve the pipe dissipating area, a kind of new pipe with grid plate is proposed in this paper. Based on the basic principle of heat transfer and energy conservation law, by finite element software ANSYS the simulation analysis of the steady-state heat transfer of the new pipeline is carried out, process of ANSYS modeling, loading and solving is introduced in detail, the distribution of temperature and stress for pipe with a grid plate is given, these can provide the foundation for the selection of the optimal diameter of the grid plate and transient heat transfer analysis of pipe.