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361.
Based on the blasting construction of a Qingdao metro tunnel, a linear regression analysis of Sodev’s em-pirical formula mentioned in the GB6722-2014 Safety Regulations for Blasting is conducted considering the geologi-cal conditions of Qingdao and collected blasting vibration monitoring data. An empirical formula to predict the am-plitude of the vibration intensity of Qingdao metro tunnel blasting is deduced, while the allowed vibration velocity,single-hole charging load and scope affected by the construction vibration are determined. © 2018, Editorial Office of "Modern Tunnelling Technology". All right reserved. 相似文献
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363.
船用非线性碟簧动力吸振器的参数研究 总被引:1,自引:0,他引:1
采用有限元法、改善的动力缩减法和数值积分法,讨论了耦合非线性碟簧动力吸振器的船体结构动力响应的计算,并通过数值优化法参数,研究了非线性碟簧动力吸振器的线性刚度、粘性阻尼、Coulomb阻尼、刚度非线性和弹簧组合系数与抑振带宽的关系,得到了若干有意义的结论,可作为船用非线性碟簧动力吸振器宽带优化设计的指导原则。 相似文献
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365.
This work analyses the influence of three types of modal matrices on the prediction of vibration response (virtual sensing), at unmeasured degree of freedoms (DOFs), on a catamaran’s main deck: (1) uncorrelated finite element (FE), (2) correlated FE and (3) experimental modal matrices.A multi-objective genetic algorithm (MOGA) framework was developed to handle the optimization and prediction processes. This framework introduces a new metric called Time–Frequency-Error Response Assurance Criteria (TFERAC) to assess the prediction quality. This metric also allows estimating the best set of modal acceleration vectors, which is a critical step in the virtual sensing process.As a case study, only 06 accelerometers and 13 vibration modes (within each modal matrix) were used in the virtual sensing. The MOGA framework’s performance was evaluated using a variance analysis test (ANOVA) between measured and predicted response signals.Results showed that: (1) any one of the modal matrices could be used successfully for virtual sensing on the main deck, that is, there is no need to use correlated FE or experimental modal matrices; (2) the newly proposed metric TFERAC leads to smaller errors in the prediction of both vibration time series and vibration spectra;(3) it is possible to perform a virtual sensing on a ship’s main deck using a limited number of sensors and a numerical modal matrix without being correlated with experimental data. 相似文献
366.
Damping materials are widely used and playing an essential role in reducing the vibration and noise of various ships and underwater vehicles. In practical engineering, damping materials are often applied over the structural surface of ships and underwater vehicles. They are generally distributed not evenly in the whole area, but locally in some vital regions. The stiffened cylindrical shell is the most representative configuration for the main structure of underwater vehicles. Therefore, research on modeling and calculation of underwater acoustic radiation from stiffened cylindrical shells locally treated with damping has high practical value. This paper introduces a mixed analytical-numerical acoustic-vibration interaction method to achieve efficient calculation of the vibration and acoustic radiation from a locally damped cylindrical shell immersed in water. Two kinds of vibration and noise reduction measures are proposed for the damping treatment of a large-scale stiffened cylindrical shell structure. Calculation and analysis are carried out for both measures. The results can provide reference for developing the technology of reducing vibration and noise from ships and underwater vehicles via damping treatment. 相似文献