engleski

Influence of ribs on strength of circular manhole cover

In this paper the displacement and stresses in the sections of circular manhole cover caused by bending load was analysed for chosen type of material. Using the software package Autodesk Simulation Mechanical, the three-dimensional linear static analysis, based on the finite element method, was performed to investigate the size of the bending stresses in the casted circular manhole cover. The analysis of the three different cover constructions was conducted. Since the circular cover with circular and radial ribs is circularly symmetrical, only one part of the geometry of the cover was analysed. Because analytical solutions are only applicable for simple geometric problems such as bending of thin circular plate, the numerical simulation of the thin circular plate was carried out. Results of the deflections and radial and circular stresses, obtained by the numerical simulation were compared with analytical solution. In the numerical simulations the equivalent stresses based on the energy theory of strength were monitored. After the verification of numerical results of the bending of thin circular plate, the increased stresses were detected on plate. For that reason the circular ribs were added on the bottom of the plate and the numerical simulation was carried out and for thus shaped cover. Due to the existence of a large equivalent stress another simulation with the addition of radial ribs was carried out. By analysing the results, it was concluded that the maximum equivalent stress passes into the circular and radial ribs at the bottom of the cover. Described numerical analysis was applied onto the covers made of ductile or gray iron.

circular manhole cover, linear analysis, finite element method, strength, ductile and gray iron

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