Wyniki wyszukiwania - BazTech

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Fatigue Behavior and Mechanism of FV520B-I Owing to the Effect of Loading Frequency on the Fatigue Property in HCF and VHCF Regime

Wang J., Zhang Y., Shi B., Zhao Q., Sun Q., Zhang Z., Lu H.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

347--357

EN

Fatigue property of FV520B-I is affected by the ultrahigh loading frequency significantly, and the ultrasonic fatigue experimental data can’t be employed directly to analyze the fatigue failure in the actual remanufacturing engineering. However few theories about the effect of loading frequency on the fatigue property of FV520B-I has ever been proposed. In this paper, both ultrasonic experiment and conventional experiment are conducted out to obtain the fatigue data. The effect of loading frequency on the fatigue data distribution is discussed firstly, its fatigue limit declines with the increase of the loading frequency. Then the fracture surface observations are captured, the fatigue property and fatigue behavior mechanism of FV520B-I is examined by analyzing the fracture surface features, crack initiation and failure observations. A new material frequency correction factor is proposed and introduced to eliminate the influence of the loading frequency on the FV520B-I fatigue property. FV520B-I empirical fatigue life conversion model and fatigue strength conversion model are established with comprehensive use of a fitting algorithm based on the combination of experimental data and classic formula. A clear understand of the effect of loading frequency on the fatigue property of FV520B-I is novel and has an important significance in guaranteeing the accuracy of the actual fatigue analysis of FV520B-I in the remanufacturing engineering.

2

Facile synthesis of hierarchical ZnO microstructures with enhanced photocatalytic activity

Miao L., Shi B., Nawrat S., Mu C, Qi K.

Materials Science Poland

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2017

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Vol. 35, No. 1

45--49

EN

Flower-like ZnO microstructures were successfully synthesized via a facile hydrothermal route without using any surfactants. The morphology of these microstructures can be easily controlled by adjusting the pH of the reaction solution. The possible growth mechanism of ZnO hierarchical microstructures was proposed based on the X-ray powder diffraction (XRD) and scanning electron microscope (SEM) results. The photocatalytic activity studies of ZnO nanocrystals demonstrated their excellent photocatalytic performance in degrading aqueous methylene blue (MB) under UV-A light irradiation. This higher photocatalytic activity of the ZnO nanoplates was mainly attributed to the exposed facets with the higher surface energy.

3

A distributed soil temperature measurement system with high spatial resolution based on BOTDR

Gao L., Shi B., Zhu Y., Wang K., Sun Y., Tang C.

Optica Applicata

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2011

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Vol. 41, nr 3

607--616

EN

This paper presents a new, recently developed, distributed soil temperature measurement sensor system, with high spatial resolution, based on Brillouin optical time domain reflectometry (BOTDR). The process of developing the distributed soil temperature sensor is introduced in detail, including the principle, materials, installation, instrumentation and calibration. The new distributed soil temperature sensor improves the spatial resolution from 100 cm to 3.3 cm, and has some other unique advantages, including long distance measurement capability, a longer life cycle, galvanic isolation, EMI immunity, good stability and ease of integration. Finally, an in situ comparison test was carried out, where results from the new sensor were compared to data measured using a standard point-mode system. This test proves that the newly developed distributed sensor is both accurate and has the capability to measure continuously the distribution of the soil temperature along the whole borehole depth, indicating that this new measure technique has a wide and powerful application potential.

4

Jacket effect on strain measurement accuracy for distributed strain sensors based on Brillouin scattering

Ding Y., Shi B., Bao X., Gao J.

Optica Applicata

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2006

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Vol. 36, nr 1

57-67

EN

Fiber jacket has a function of protecting fibers from harsh environment; it also has an impact on the measured strain accuracy. In this paper, we report on our study of jacket effect to distributed Brillouin sensor system on strain measurement accuracy for constant load stretching and constant length stretching using the 900 m tight-buffered fiber (Type-A) and the 250 m optical fiber (Type-B). We have studied the time-varying performance under the stretching of constant load and length. It was found that, within 48 hours under constant load stretching, the strain value of the Type-A measured by BOTDR (Brillouin optical time-domain reflectometer) increased with time, while the Type-B it kept stable. Within 48 hours under constant length stretching, the strain value of the Type-A decreased with time, while the Type-B it kept stable. After relaxation, the strain value of the Type-B reached zero within 1 hour, while the Type-A declined gradually. We found the creep deformation and stress relaxation of jacket to be the leading cause to this phenomena.

5

Improvement of spatial resolution of Brillouin optical time domain reflectometer using spectral decomposition

Zhang D., Shi B., Cui H.L., Xu H.Z.

Optica Applicata

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2004

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Vol. 34, nr 2

291-301

EN

Brillouin optical time domain reflectometer (BOTDR) has been used for strain and temperature measurement and health monitoring in infrastructural systems. However, the spatial measurement resolution of BOTDR cannot yet meet the measuring needs of some specific local strains, such as the strain caused by a narrow crack or fissure in structures. In this paper, a spectral decomposition method is proposed and used for improving the spatial resolution. Based on the proportion of the strain length within the spatial resolution, taking the spectrum of the strain section from the measured spectrum, and fitting the decomposed Brillouin gain spectrum with the Lorentzian curve, the actual strain within a spatial resolution along optical fibers can be obtained. The experimental results demonstrate that this method is applicable to the modification of the measured strain whether its strained length is less or greater than the spatial resolution without considering the installation method of the optical fiber