Applied Mechanics and Materials Vols. 249-250

Abstract: This article introduces the method of selection and related criterion of standard copper-cylinder, and systematically analyzes five factors that affect the measuring uncertainty of standard copper-cylinder: primary pressure standard, height measuring of copper-cylinder, and inconsistent individual deformation of standard copper-cylinder, inconsistent pressure sensitivity and the influence of temperature. According to usage characteristics and selection methods of the standard copper-cylinder, discusses computing method of components of the measurement uncertainty and models measuring uncertainty of standard copper-cylinder. The model can quantitatively calculate through experimental data of selection, which lay a theoretical foundation for the control of the pressure measuring uncertainty of standard copper-cylinder.

Abstract: Quantum efficiency of organic/hybrid solar cells has improved appreciably in recent years and it is useful to re-examine those parameters that reflect the device properties. This is important when there is need to distinguish between improvements associated with materials properties such as domain size and phase separations and improvements linked to external effect such as the inclusion of field enhancement layers. In this work, we reported the evaluation of the “internal” resistivity found in high performance organic/hybrid solar cells based on data reported in the literature. Our observations suggest that in general better device performance is found in devices with higher “internal” resistivity. This includes the case when a hole blocking layer is added. Exceptions to such a rule can be found in solar cells with nanowires in the n-layer and ferroelectric end layers whereby the quantum efficiencies increase beyond the values expected. A simple mathematical model has been put forward to explain the dependence of quantum efficiency on the “internal” resistivity. Overall, lowering of the “internal” resistivity correlates well with degradation in the device performance and can be put in the context of a reduction in the effective diffusion length of the photo-excited carriers. High field and polarization effects by themselves do not affect the “Internal” resistivity.

Abstract: To measure the propulsion characters of PVC(poly vinyl chloride) doped with carbon ablated by high power density laser, torsion pendulum is used to measure the micro impulse. Laser interference is used to detect the vibration of the pendulum which is caused by the ablating jet. The measurement error is 2.6 according to the calibration. Nd:YAG laser is used as the laser source. Mettler-Toledo XS105DU analytical balance is used to measure the ablated mass. The results indicate that the performance of PVC+2C is better as an alternate target. Both the specific impulse(Isp) and energy transforming efficiency() increase with laser power density(I0), while momentum coupling coefficient(Cm) decreases. The maximum measured Cm is 557N/W. Isp and  reach to 204s and 46 respectively.

Abstract: 8 pressure vessels of carbon fiber reinforced plastics (CFRP) have been manufactured with in the winding technology of same continuous carbon fiber–-amine system, new same flexible formula and same tension system. And the hydraulic bursting tests with the specimens were done in accordance with GB6058-85. The parameters of fiber strength, winding angle, geometric sizes and burst pressure were obtained by the tests. The theoretical analysis was done by conventional design method and reliability design method. The results show that: the theoretical calculating thickness of CFRP pressure vessel with by same parameters is thicker than practical thickness. This shows the performance of CFRP pressure vessel is related not only with fiber strength but also with material properties of resin matrix, tension and solidifying system of winding process. Because of CFRP (Carbon Fiber Reinforced Plastics) have many advantages which are high specific strength, high specific modulus, ablation resistance and low cost. Although the thing that composite materials have been substitutes for metal shell springs up soon, the application is much wide[1-6].

Abstract: In order to study the humidity sensing property and sensing mechanism of Al-doped mesoporous silica SBA-15 (Al-SBA-15), Al-SBA-15 was prepared by a simple grind method following a heat-treatment process. Its structure and morphology was characterized by X-ray diffraction (XRD), Infrared (IR), scanning electron microscope (SEM). Humidity sensing response was studied and the results indicated that Al-SBA-15 displayed better sensing property when the frequency was 100 Hz. The impedance of Al-SBA-15 changes three orders of magnitude when relative humidity changes from 11% to 95%. Complex impedance spectra, the corresponding equivalent circuit under different relative humidity are carefully analyzed to explore the humidity sensing mechanism of this material. This material can be used as a promising humidity sensing material.

Abstract: This article divides the motion route into four phases: free fall, initial collision, in-flight and subsequent collision. There could be bounce, slippage or rolling movement in the phases of initial collision and subsequent impact. Based on the theory of movement mechanics, the certain methods on the motion direction, velocity and distance of each movement mode is established and the effected discrimination standard to distinguish the motion phases and modes is put forward.

Abstract: Blasting vibration not only damages architectural structures but also harms people heath. Numerical simulation provides an effective method to study explosion and shock problems. Herein, the paper performed numerical simulation to predict blasting vibration. At first, analyzed the propagation velocity of stress wave, which validated the feasibility of the model. The simulation and test agreed well both at vibration waveform and at the order of magnitude of both nodes 1 and 2. The simulation could provide reasonable accuracy. The achievement provided reference for other researches.

Abstract: In advanced marine industry, the reduction in weight of hull structures for a very large object ship plays an important role as the economic efficiency is the most significant aspect. In this paper, we investigate the ultimate strength of structural ship stiffened-plates designed by International Association of Classification Societies (IACS) Common Structural Rules (CSR) methods of collapse state, by applying for ANSYS nonlinear finite element analysis (FEA). Specifically, the ultimate limit assessment methods for the outer bottom of ship structures, which have drawn a significant attention from industrial marine and offshore structures, are proposed to reduce the weight of ship structures. To solve this, we study the structures of a hypothetical Very Large Ore Carrier (VLOC) designed by pre-CSR and CSR methods. In particular, the stiffened-plates under the biaxial compression and lateral pressure loads with simply supported or/and clamped boundary condition(s), the results ultimate limit state assessment performance of Nonlinear FEA methods are shown and compared to various states.

Abstract: We developed a CFD code applies the omni-tree Cartesian grid to simulate the flow fields around one civil-plane high-lift model using the multi-zone technique. With a face-to-face algorithm, the flow control equations are solved numerically, in combination with the cell-center finite volume method and dual-time stepping scheme. The computed results are in good agreement with the experimental data and show preliminarily that numerical method is effective.

Abstract: To the aircraft structures system, there are lots of factors which will lead to the inevitable performance degradation or faults, such as the corrosion of the external environment, the fatigue causing by the varying loads, degradation of material properties and so on. Based on the monitoring parameters of the structures, Structural Health Monitoring (SHM) technique can comprehensively assess the status of the structure and its damage. All results of SHM are useful to extend the structural life, reduce maintenance costs and improve the safety and reliability of the structure. In this paper, taking a wing structure as example, the acceleration responses under the natural excitation can be obtained. With NExT-ERA method, the modal parameters of the wing structure can be calculated. Comparing with the finite element results, the numerical results of NExT-ERA method can be proved that they are credible and accurate. All the results indicate that, without destroying the structure situation, the NExT- ERA method can accurately identify the wing structure modal parameters.