IDEALIZING THE DESIGN MODEL OF THE ROPE PART OF THE MIDWATER TRAWL
The article presents a perspective approach to the analysis of a stress state of net gear. A set of assumptions and simplifications of determining the forces acting on the end part of the trawl have been proposed. In terms of strength analysis of the trawl gear elements, the rope section deserves a thorough study, since the rope section elements are subject to the most uneven tension. In addition, the rope section of the trawl is the most material-intensive. The mass of the rope trawl is about 2/3 of the total mass of the trawl. Therefore, it is important to determine the minimum rope diameter without losing its strength. It is evident from the analysis of the trawl construction scheme that the trawl is presented in the form of a limited number of one-dimensional finite elements linked in the nodes of a rope net. Rope length from the attachment point up to the bare end inclusive is also considered a single straight element. Each element is affected by the force of hydrodynamic resistance, the force of weight and some longitudinal force. When analyzing the design model, hydrodynamic lifting devices are substituted by concentrated forces applied to the nodes of the headline; loads on the low rope are also substituted by concentrated forces. Knowing their orientation relative to the stream flow, it is possible to calculate the reactions in the nodes of the elements using the node coordinates. Formulas determining the forces that act on the finite element of the trawl rope part have been proposed, which can be used to compile a program for calculating the strength of the rope part of mid-water trawls.