Applied Mechanics and Materials Vols. 284-287

Abstract: In this paper, a method combining stereo vision and digital phase-shifting techniques is presented, which can measure the profile of complex freeform surfaces expeditiously and accurately. A chessboard is used to determine the camera parameters for the camera calibration of the system and the epipolar line rectification is executed based on the stereo calibration result. The stereo matching is processed with the combination of four-step phase-shifting and Gray code techniques, and the maximum probability method is proposed to remove the fringe order confusion problem between Gray code and phase shifting measurement. Bilinear interpolation method is also adopted to improve the speed and accuracy of stereo matching. Experiments were carried out with measuring a step gauge block and a shoe last model. Experimental results show that the measurement can be completed within 3 s for a measuring region of 640 mm × 480 mm, and the average measurement error is less than 0.054 mm.

Abstract: The purpose of this paper is to develop a novel three-speed geared motor that integrates a basic epicyclic-type gear train with an exterior-rotor brushless DC (BLDC) motor to form a compact structural assembly. Unlike existing gear motors, the proposed device provides three speed ratios including an under drive, a direct drive, and an over drive, and is operated with a single clutch-to-clutch shaft. It provides a wider speed range than the traditional geared motor. Such an integrated design can be appropriately employed in high driving torque and low rotational speed applications or high rotational speed and low driving torque applications.

Abstract: Integrated designs of brushless permanent-magnet (BLPM) motors and basic planetary gear trains (PGTs) are described in this paper. The kinematic characteristics of the basic PGT and the typical topologies of the BLPM motor are studied first. Then, design requirements are concluded to rationalize the integrated designs. Four novel integrated devices with interior and exterior topologies are synthesized subject to design requirements. The unique characteristics and application fields of the proposed designs are also indicated.

Abstract: The current evaluation of machine tools’ machining performance relies on instruments measurement but not actual/real machining method. However, using instruments measurement evaluation is not only costly but also due to the installation defect of instruments, resulted in performance examination errors. This paper proposed to use titled condition of 10-15 degrees on the base of part’s clamp with VERICUT software to perform simulation for achieving the purpose of examine tools’ machining performance. Findings showed that under the tilted condition of 10-15 degree, turn-mill type of interruptions occurred and unable to proceed. Modification on the cone frustum and anti-cone frustum design was applied to overcome turn-mill interruptions issues. This simulation results showed achievement of turn-mill type tools’ machining performance evaluation with anti-cone frustum design.

Abstract: This article reviews how the constructal law governs the design and evolution of flow configuration in nature and engineering. The flow systems evolve by acquiring flow configuration in a definite direction in time if it is free to morph: existing configurations are replaced by easier flowing configurations. One example accounts for this evolution given in this article comes from natural inanimate flow systems: tree-shaped flows. The applications of constructal design method in the fields of heat transfer and fluid flow in engineered systems are also reviewed. The application of multiobjective configurations in the venturi cooling device is studied. In sum, this paper presents an overview of recent developments of constructal design of configuration in engineering. Some discussions and future prospects on this novel research field are provided in this paper to show the emerging development of constructal theory in engineering and other branch fields.

Abstract: A lumped-parameter numerical model was constructed based on the conservation laws of mass and energy and the point neutron kinetics with 6 groups of delayed neutron to represent the dynamics of primary loop of a pressurized water reactor (PWR) core. On the viewpoint of control theory, the coupled phenomenon of neutron kinetics and thermohydraulics can be recognized as a dynamic system with feedback loops which is caused by the Doppler effect and the coolant temperature difference. Scilab was implemented to representing the equivalent transfer functions and associated feedback loops of a PWR core. The dynamic responses were performed by the perturbations of coolant inlet flow, coolant inlet temperature, and reactivity insertion.

Abstract: Since the fairly high temperature in fire scenes combined with the high temperature of LED, the water-cooling is proposed to solve the challenge of the existing thermal problem of the flashlights used by fire fighter. A Nozzle Light is lighten by a portion of the hydropower in the water passing through a fire nozzle is harvested. The water is used to drive a micro-turbine alternator and generate electrical power to light up LED lighting. When the water is discharged from the fire nozzle, we find that the maximum temperature on Nozzle Light is only increased 1.3°C compared to the 24°C of that without water. It shows that water-cooling effect of large-amount of water indeed lower the temperature increment. The LED operated under lower ambient temperature has higher relative luminous flux and longer lifetime. It reduces the firefighting loadings of firefighters and raises their safety.

Abstract: The acoustic horn plays a very vital part in high energy ultrasonic machining, and its design is critical to the quality and the efficiency of machining. This paper performs the analysis and design of acoustic horns for ultrasonic machining by employing ANSYS finite element software. Firstly, the theoretical dimensions of the horns are calculated and compared to three commercial available horns with different shapes. Moreover, their natural frequencies and amplitudes are obtained through the simulations of ANSYS. Finally, the numerical results are compared with commercial available horns. The results indicate that not only the natural frequencies of horns designed by theoretical models are more close to the vibration frequencies of ultrasonic generators, but also their amplitudes are superior to commercial available horns. Therefore, the trial and error time, for horn machining and dimensional modification of the horn design, can be greatly reduced by the proposed approach of this work.

Abstract: Linear machines are widely employed in robotics, transportation and manufacturing industries because complex rotation-to-translation conversion mechanism is no longer required. This paper proposed a novel tubular linear machine with dual permanent magnet (PM) Halbach arrays to achieve high force output performance. Based on Lorentz force law, the magnetic force output and force ripple for three-phase winding linear machine is formulated in analytical way. By taking advantage of the analytical models, the force output is simulated with respect to the motion of the mover. Numerical result is then obtained to validate the analytical force models. In addition, based on the technology of non-dimensionalization, the mathematical force models are employed to analyze the influence among the structure parameters on the force output and force ripple for design purpose of the tubular linear machines. The study in this paper could contribute to the design analysis and optimization of electromagnetic linear machines with similar poles patterns.

Abstract: The present study proposes a laser-based microscope system in which a precise autofocusing capability is achieved using a position feedback signal based on the distance L between the geometrical center (Xc, Yc) of the image captured by the CCD sensor and the centroid (xcentroid, ycentroid) of the image. The experimental results show that the proposed system has a positioning accuracy of 2.2 μm given a working range of ±200 μm. The autofocusing performance of the proposed system is thus better than that of a conventional centroid-based system, which typically achieves a positioning accuracy of around 5.2 μm.