Applied Mechanics and Materials Vol. 590

Abstract: The thick wall pipes have been widely used in the field of petrochemical industry, nuclear power, weapons and special equipment. In this paper, the propagation characteristics of circumferential Lamb wave in thick wall pipe and the interaction law with radial cracks were studied. A large number of simulation were carried out by using the commercial finite element software ABAQUS. The propagation characteristics of circumferential Lamb wave in thick wall pipe were analyzed. The research results show that the propagation process of Lamb wave in thick wall pipes are totally different from with that in the thin wall pipes, the energy distribution in the wall thickness direction are changing constantly. It is hard to evaluate the depth of smaller defects. The influence of various factors on acoustic field distribution should be considered synthetically in the practical inspection, such as the size of crystal, the angle of wedge, the excited signal. So detection sensitivity of the small defects can be improved.

Abstract: A thermodynamic analysis of the ejector expansion refrigeration cycle (EERC) was carried out based on a two-phase flow model. First the ejector parameter was optimized under the given condition. Then the influence of condenser temperature and evaporator was investigated. Numerical simulation result shows that the EERC always has a better performance than the basic system. When the evaporator is 0°C, the system COP can be improved by 18.6%.

Abstract: In this paper, three-dimensional wind-induced vibration control is investigated by using multiple tuned mass dampers (MTMD). A 20-story steel frame is take as a numerical example to compare the two control effects by using MTMD and TMD (tuned mass damper), in which the same control masses are set on the top floor respectively. The parameters and locations of the damper devices could be chosen optimally based on energy balance theory and genetic algorithm. Numerical results show that the total damp value and the total structural dissipative energy of MTMD is lower than TMD while the total mass are the same. Meanwhile, MTMD also shows a better performance on reducing the along wind displacement and torsion response of the structure than that of TMD.

Abstract: The coupling characteristic of the tool-holder/spindle interface in high speed NC machine has significant influence on machine tool accuracy and process stability. With the example of HSK-E63, based on nonlinear finite element method (FEM), the coupling characteristic of the tool-holder/spindle interface under high rotational speed was investigated, the influence of interference, clamping force and rotational speed on the contact stress and the sectional area of clearance were discussed in detail. The results can be used as theoretical consideration to design and optimize the high speed tool-holder/spindle interface.

Abstract: It is important to calibrate the straightness and the squareness of the XY-stage for precision manufacturing and measurement. Normally it is calibrated using much higher precise and accurate measuring instruments and/or artifacts. The high precision and accurate instruments and artifacts are expensive. So, in this paper, Self-calibration method is applied to XY-stage. This method does not require any much high precision and accurate instruments and artifacts. The normal XY-stage moves to the location at the unique coordinates. In this case, it is difficult to apply self-calibration method. Therefore, XY-stage is expanded to XYθ-stage with parallel mechanism. As this stage moves to the location at a lot of coordinates, self-calibration method is applied. This method is confirmed in simulation and experiment. In simulation, the extension lengths of mechanism are estimated from known kinematic parameters and the target coordinates. After that, estimated kinematic parameters are calculated by least-squares method from the extension lengths and the target coordinates. Finally, the positioning coordinates are calculated from the estimated kinematic parameters and the extension lengths. It is proved that the calibration method is effective by comparing the target coordinates and the positioning coordinates. In experiment, the experimental process is similar to the simulation without the estimation of extension lengths. The results of simulation and experiment are shown in this paper.

Abstract: This paper, taking a mine dump truck as the research object, analyzes CAE by the principle of the finite element’s inertia and finds out the initial problem of the design, thus optimizing the frame structure reasonably. Thereby it can reduce the cost of the production’s design and shorten development cycle of new models.

Abstract: Based on the European New Car Assessment Program, which offers rigorous testing conditions, this study developed a numerical model for the computer simulation of crash analysis and analyzed two crash situations: a high-speed vehicle crashing into a wall and a high-speed test vehicle crashing into a static vehicle. The Simulation model was constructed using the superior functions of the Patran software, and the Pam-crash software was employed to perform various calculations for analysis. In crashes, the structure of vehicle bodies are greatly compressed and deformed because of high-speed impact force, which simultaneously generates high speed acceleration. Vehicle structural deformation constricts the driver and passengers, and acceleration can cause them physical harm. Thus, the objective of this study was to identify the sources of harm to driver and passengers when crashes occur. The research results can be a reference for vehicle manufacturers in future vehicle development and a reference for future academic research.

Abstract: The dynamic wind loadings of solar panel mounted on flat roof building model were checked with a series of wind tunnel aerodynamic test. In this study the location and wind angle are controlled factors. The results shown that for the panel located near downstream area and its high end is facing the inclined oncoming flow might be the extreme condition, in which the panel is suffered by the highest up-lift forces. Beside the wind pressures coefficients, we have also calculated the co-spectrum of pressures signals at variant faces of panel and roof edges. With the results we found the high fluctuating and extreme wind dynamic loading on panel might come from the well correlation of building roof-top shedding vortices to the panel surface, not the separation shear layers by panel itself.

Abstract: Problems of estimation of vibration isolation effectiveness are discussed based on vibratory power flow analysis, and a new insertion loss character — power flow insertion loss is proposed for evaluation of isolation efficiency. Spectra characteristics of the power flow insertion loss and their relationship with transmitted power flow and vibration level difference are investigated through numerical simulation. And in consideration of the inconvenience of practical testing of insertion loss and power flow, an attempt is made to set up numerical correspondence between power flow insertion loss and the current widely applied vibration level difference measurement, through theoretical analysis and experiments.

Abstract: In order to improve the conveyance stability of rubber tires on the curved roller of the automated production line, this paper analyzes the causes behind the conveying instability of tires on the curved roller in terms of the principles, and studies the relationship between the main design parameters of the roll curved conveyor line and the conveying instability of tires, providing a reference basis for the design of a stable roll curved conveyor line.