Applied Mechanics and Materials Vols. 764-765

Abstract: In this investigation, the weight function method was employed to calculate the stress intensity factors for semi-elliptical surface crack in a hollow cylinder. An uniform stress and a linear stress distributions were used as the two references to determine the weight function. The weight function was then applied to a wide range of semi-elliptical surface cracks subjected to non-linear loadings. The stress intensity factors obtained by the weight function were compared with literature results. Good agreement demonstrates the accuracy of the present approach.

Abstract: The paper is concerned with the frequency reliability sensitivity and related robust analysis problem for the random continuous vibration structure systems. Reliability analysis based on frequency is necessary for reliability problems of uncertain vibration structure systems. With the criterion that the absolute value of the difference between the natural frequency and forcing frequency, the reliability mode and the safety probability of the random systems are defined, and then The frequency sensitivity analysis method is quested by using the random perturbation technique, the reliability theory and sensitivity approach. Furthermore, the frequency reliability-based robust method of the random dynamic structural system was obtained by the robust and the optimization technology on the basis of frequency reliability and sensitivity design, which helped designers to establish acceptable parameter values and to determine the fluctuations of the parameters for the safe operations. Moreover, a numerical example is provided to demonstrate the effectiveness and accuracy of the proposed method. This study established theory basis for sensitivity and robust evaluation.

Abstract: In this investigation, the methodology for predicting the dynamic response of a composite laminate shell subjected to low velocity impact is presented. A non-linear integro-differential equation is derived and solved by the numerical scheme of Runge-Kutta method to obtain the time history of the contact force at the impact point of the shell. The contact force is then taken as external force acting on the apex of the shell and solved by the finite element method. The results are validated with the numerical calculation published in the literature.

Abstract: 3D nonlinear impact analysis of a reinforced concrete bridge column under truck impact loadings was performed in this study. Three different boundary conditions were considered in order to investigate the effect of superstructures for the integral column during the impact. A fixed condition at bottom and restrained in a loading direction at top (Model I) showed the largest damaged area and dominant failure mode of the column was shear. However, Model II (Model I with released at top) showed smaller damage and dominant failure modes were flexure rather than shear. In Model III, it was found that the superstructure intensifies the shear and flexural damages to the column due to the dynamic movement of the superstructures

Abstract: This study performed 2D analysis for suspension bridge to predict the bridge superstructure oscillation induced by wind load. Previous studies exhibited that a large torsional mode can be generated by continuous vertical modes in suspension bridge. However, the previous studies did not consider torsional resistance of the superstructure and unrealistic results were shown as wind speeds increasing. Therefore, this study developed a new model considering torsional resistances and predicted responses of a suspension bridge. Analysis results exhibited that vertical oscillations were transformed to the torsional oscillations. With varying torsional resistances, vertical responses were stabilized over a time. However, the rotational response amplified at resonance points. Also, it was found that the resonance of the rotational mode depended on the torsional resistance.

Abstract: In the present study, nonlinear free vibration behavior of nanobeam subjected to magnetic field is investigated based on Eringen's nonlocal elasticity and Euler–Bernoulli beam theory. The Hamilton's principle is adopted to derive the governing equations together with Euler–Bernoulli beam theory and the von-Kármán's nonlinear strain–displacement relationships. An approximate analytical solution is obtained for the nonlinear frequency of the nanobeam under magnetic field by using the Galerkin method and He's variational method. In the numerical results, the ratio of nonlinear frequency to linear frequency is presented. The effect of nonlocal parameter on the nonlinear frequency ratio is studied; furthermore, the effect of magnetic field on the nonlinear free vibration behavior of nanobeam is investigated.

Abstract: Biological treatment process of water purification often cannot be completed under low temperature in northern rural areas. On the basis of determining the thermal characteristics of clarification pool and biofilter pool of the purification systematically, we designed and proposed a purification heating system in which solar collector and straw boiler run in parallel, and further built the mathematical model of purification. We simulated heating effect on clarification pool and biofilter pool when heating pipes were placed in different locations by using Fluent. It indicated that, the heating system mentioned in this article allows the temperature in clarification pool and biofilter pool of the purification meeting the demands of water treatment, thus the system has theoretical significance and value of engineering generalization.

Abstract: Cyclic loadings would cause the failure of pile foundation which was leading to many studies in the past. In this study, 6 centrifuge models were conducted in the acceleration field of 80 g. In order to simulate the off-shore wind turbine foundation embedded in soft deposit and subjected to lateral forces such as strong wind and waves. The pile was embedded in the dry or saturated soil deposit, and the different elevation of lateral force was applied to the pile foundation. From the tests, it was found 1% of pile head displacement suggested in the design guide is conservative.

Abstract: In this paper, we develop the auto-focus measurement system which includes the hardware and software systems. The hardware system is composed of both modules of the motion stage and the auto-focus optic-mechanism. And the software system consists of two phases: (1) training the response surface model (RSM) for auto-focus technology in offline phase and (2) automatically capturing mesh images by RSM and robustly measuring holes by the area-based diameter (ABD) and average diameter (AD) in online phase. The experiments presented that the proposed auto-focus technology using RSM can effectively obtain the correct focusing position. The accuracy of the diameter on a hole can reach up at most 0.891 μm using the above two algorithms. The successful measure rate is almost 98 %; the measure time is averagely 4.8 seconds per mesh. The above results revealed that the proposed system is not only robust for the auto-focus technology but also efficient and effective for the mesh membrane measurement.

Abstract: In this paper, we investigate the two-photon recording system in a 50-layer structure with each recording layer contains 4.7GB of data, similar to the capacity of a single layer Digital Versatile Disc, as the total capacity is 235GB/disc. We present a single-laser system to realize recording and reading and propose a new multilayer disc structure in which the groove structure is set on the substrate for servo control, the laser is separated by a PBS to two parts, one for recording and the other for servo in the optical system. Our research shows the feasibility of high density optical data storage using a single laser in a multilayer structure.