Net cage state detection method based on modal analysis in marine environment

A marine environment and modal analysis technology, applied in the testing of machines/structural components, measuring devices, instruments, etc., can solve the problems of limited sonar accuracy, high equipment cost, high maintenance cost, etc., and achieve low cost and accurate information acquisition Effect

CN112903243AActive Publication Date: 2021-06-04ZHEJIANG UNIV
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2021-06-04

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Abstract

The invention discloses a net cage state detection method based on modal analysis in a marine environment. The method can be used for monitoring whether a net cage is damaged or not and estimating incoming flow around the net cage. By analyzing the mode of the net cage, the inherent frequency excited by the net cage under the action of ocean current is compared to judge the net cage state and ocean current parameters. A sensor involved in the net cage state detection method is a small pose sensor or a stress sensor, and compared with the characteristic that an underwater camera or underwater sonar or other state detection methods are limited by water quality, the net cage state detection method is more suitable for the marine environment, and has more prominent advantages in cost and later maintenance.
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Description

technical field

[0001] The invention belongs to the field of fluid-solid coupling and modal analysis, and reversely infers the state of the net cage and the state of incoming flow by detecting the vibration form of the net cage under the action of the ocean current, and specifically relates to a state of the net cage based on modal analysis in a marine environment Detection method. Background technique

[0002] Fluid-solid coupling mechanics is a branch of mechanics generated by the intersection of fluid mechanics and solid mechanics. It is a science that studies the interaction of various behaviors of deformed solids under the action of a flow field and the influence of solid configuration on the flow field. . The important feature of fluid-solid interaction mechanics is the interaction between two-phase media, and the deformed solid will deform or move under the action of fluid load. Deformation or movement affects fluid movement in turn, thereby changing the distributio...

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Embodiment Construction

[0032] The present invention will be further explained below in conjunction with the accompanying drawings.

[0033] First of all, the theoretical proof is carried out. The following proof is only to approximate the form of the solution of the cage vibration:

[0034] Since the cage hangs heavy objects and is impacted by water flow, it can be regarded as an elastic surface with tension evenly distributed along the horizontal and vertical directions. Such as figure 1 Shown is the state of the net cage when the force is balanced, and the whole is a cylindrical shape inclined after the force is applied.

[0035] The present invention mainly comprises following four parts:

[0036] 1. The vibration exists only in the vertical section

[0037] Make slices along the vertical direction, such as figure 2 As shown, the head end is fixed, and the weight hanging at the end is slightly bent under the impact of ocean currents. The coordinate system x0z is established along the line. ...