Torsion of a conical shell weakened by a not inconsiderable circular hole

The article studies different shell constructions of mid-water trawls and their properties. The problem settled is suggested to be solved taking into account real geometric interrelations between spacious and surface properties of cone shells. The author suggests to accept a so-called geometric quality coefficient as a criterion of the properties of a conical shell, which represents the ratio of the shell to the area of its side surface and by analogy to use it to the shell of the trawl. The relationship between the trawl dimensions and geometric quality coefficient have been studied. Comparing these figures with the actual characteristics of trawls showed good convergence. According to the results of theoretic analysis and parameters calculation, trawl large-size shells will always have advantages in geometric characteristics over mid-size and, especially, small-size shells. The results of the analysis can be used for approximate calculations of the parameters of the trawl and justification of ways to improve the performance of existing mid-water trawls.

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Stability and vibration analysis of an axially moving thin walled conical shell

Journal of Vibration and Control ◽

10.1177/1077546321997600 ◽

2021 ◽

pp. 107754632199760

Author(s):

Hossein Abolhassanpour ◽

Faramarz Ashenai Ghasemi ◽

Majid Shahgholi ◽

Arash Mohamadi

Keyword(s):

Natural Frequency ◽

Conical Shell ◽

Shell Theory ◽

Cone Angle ◽

Theory Of Elasticity ◽

Lower Velocity ◽

Motion Equations ◽

Conical Shells ◽

Divergence Instability ◽

Axially Moving

This article deals with the analysis of free vibration of an axially moving truncated conical shell. Based on the classical linear theory of elasticity, Donnell shell theory assumptions, Hamilton principle, and Galerkin method, the motion equations of axially moving truncated conical shells are derived. Then, the perturbation method is used to obtain the natural frequency of the system. One of the most important and controversial results in studies of axially moving structures is the velocity detection of critical points. Therefore, the effect of velocity on the creation of divergence instability is investigated. The other important goal in this study is to investigate the effect of the cone angle. As a novelty, our study found that increasing or decreasing the cone angle also affects the critical velocity of the structure in addition to changing the natural frequency, meaning that with increasing the cone angle, the instability occurs at a lower velocity. Also, the effect of other parameters such as aspect ratio and mechanical properties on the frequency and instability points is investigated.

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