Structural Analysis Of The Signaling Buoy Used In Relaying Areas Of Live Bivalve Mollusks

Abstract

The diseases caused by the Norwalk virus (norovirus, Caliciviridae family), which produces gastroenteritis, and HAV (hepatitis A virus), and consequently generates infectious hepatitis, are the most common infections associated with the consumption of contaminated bivalve mollusks, raw or under-cooked. Moreover, the mutual commercial agreement between the EU and the USA regarding the export of live bivalve mollusks requires the adoption of a control program for the microbiological classification and monitoring of the production of this type of seafood, as well as the clear demarcation and signalling of the relaying areas. In this sense, in order to obtain the natural purification of live bivalve mollusks, the relaying areas, as freshwater, sea, estuaries or lagoons, must be demarcated and signaled with the help of buoys. The mathematical modeling of the geometric domain was performed with specialized software based on dimensional constraints specific to an algebraic surface of 2nd order – frusta of cones welded at large end, with different volumes for each frustum. The dimensions for the emerged/submerged frustum were: slant height: 630mm/800mm, radius of the larger circular front: 600mm/600mm and radius of the smaller circular front: 200mm/256mm. The Generative Structural Analysis module enabled the simulation of the behavior of the buoy both as a single entity and as a set of broken (individual) entities. The loads were carried out in the extreme conditions of the open sea, corresponding at: i) agitation state of 4 - 8 degrees Beaufort (wind speed 11 - 15 kt, respectively 20 - 88 km/h) and wave height of max. 1.5 m; ii) wind speed of 34 - 40 kt (62 - 74 km/h) and wave height of 6-7.5 m. Two types of constraints were considered both at the base and in the frusta joint area. Analysis of displacement fields and equivalent stresses (Von Mises) evidenced that the buoy is a rigid structure (with reduced maximum displacements, of 1.2e+003 mm, for 8bf), with an admissible resistance of emerged/submerged frustum 8.11e+ 009N_m2 /1.75e+009 N_m2 that enables the retrieve of the efforts due to the environment, as the possible cracks that might appear at the contact of the composite structure with the fluid in turbulent motion exceed the value of 7.83e+009N_m2 for the stress at 8bf. In addition, were considered for the emerged/submerged frustum: slant height: 630mm/800mm, radius of the larger circular front: 600mm/600mm and radius of the smaller circular front: 200mm/256mm. In this situation, a CAD/CAE environment enabled the simulation of the behavior of the buoy both as a single entity and as a set of broken (individual) entities was performed. Moreover, for the matrix made of 45%/55% PA6.6/PES fabric –corresponding to the emerged frustum and respectively 100% PA6.6 for the submerged frustum were used calculation algorithms specific to fabric design. The resulting variation intervals of the longitudinal, respectively transverse system, mass, width and connection were assessed. The buoy obtained based on mechanic-textile processing technologies will be subjected to experiments at the shore and in real conditions of use, in order to determine the corresponding technical resource.

Keywords: mathematical modeling, numerical analysis, constraints, structural parameters, structure programming.

DOI: 10.54941/ahfe1003646