Transactions of Nanjing University of Aeronautics & Astronautics
Forced Resonance of a Slightly-Curved Hydraulic Pipe Fixed at Two Ends
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Abstract:
The ideally straight hydraulic pipe is inexistent in reality. The initial curve caused by the manufacturing or the creep deformation during the service life will change the dynamic character of the system. The current work discusses the effect of the initial curve on the hydraulic pipe fixed at two ends for the first time. Based on the governing equation obtained via the generalized Hamilton’s principle， the potential energy changing with the height of the initial curve is discussed. The initial curve makes the potential energy curve asymmetric， but the system is always monostable. The initial curve also has very important influence on natural frequencies. It hardens the stiffness of the first natural mode at first and then has no effect on this mode after a critical value. On the contrast， the second natural frequency is constant before the critical value but increases while the height of the initial curve exceeds the critical value. On account of the initial value， the quadratic nonlinearity appears in the system. Forced resonance is very different from that of the ideally straight pipe under the same condition. Although the 2∶1 internal resonance is established by adjusting the height of the initial curve and the fluid speed， the typical double-jumping phenomenon does not occur under the initial curve given in the current work. This is very different from the straight pipe in the supercritical region. The work here claims that the initial curve of the hydraulic pipe should be taken into consideration. Besides， more arduous work is needed to reveal the dynamic characters of it.
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Project Supported:
The work was supported by the National Natural Science Foundation of China （No.12002195）， the National Science Fund for Distinguished Young Scholars （No.12025204）， the Program of Shanghai Municipal Education Commission （No.2019-01-07-00-09-E00018） and the Pujiang Project of Shanghai Science and Technology Commission （No.20PJ1404000）.
Clc Number:
O326
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