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Magistrska naloga obravnava vpliv osnosimetričnega prednapetja tankega diska na njegove napetostno-deformacijske lastnosti. Vsak disk ima specifično hitrost vrtenja, pri kateri izgubi stabilnost ter začne prečno nihati, kar ni zaželeno predvsem v industriji krožnih žag. Cilj prednapetja je povečanje togosti diska, kar posledično zviša tudi njegove lastne frekvence in kritično vrtilno hitrost. Zato smo želeli preveriti, če lahko z metodo končnih elementov uspešno simuliramo proces prednapetja z valjčki. Za validacijo rezultatov smo izbrali prednapet komercialno dosegljiv disk, ki smo mu izmerili prečno togost in prečni profil žlebu. Ugotovili smo, da se rezultati simulacij dveh različno poenostavljenih modelov ujemajo z eksperimentalnimi meritvami. Analizirali smo vpliv sile prednapetja in radija valjanja na togost in lastne frekvence diska. Ugotovili smo, da je bil komercialno dosegljiv disk prednapet s silo valjanja 8,9 kN ter valjan na optimalnem radiju 100 mm. Kritična modalna oblika diska je bila oblika z dvema vozliščnima premeroma, pripadajočo lastno frekvenco pa smo s prednapetjem zvišali za 8,66%. This master's thesis deals with the influence of axisymmetric prestressing of a thin disc on its stress-strain properties. Each disc has a certain rotational speed at which it loses stability and starts to oscillate laterally, which is not desirable, especially in the circular saw industry. The aim of prestressing is to increase the stiffness of the disc, which in turn increases its natural frequencies and critical rotational speeds. Therefore, we wanted to find out whether the finite element method can be used to successfully simulate the process of prestressing. To validate the results, we selected a commercially available prestressed disc and measured its transverse stiffness and groove profile. We found that the simulation results of two differently simplified models agree well with the experimental measurements. The influence of the prestress force and the rolling radius on the stiffness and natural frequencies of the disc was analysed. We found that a commercially available disc was prestressed with a rolling force of 8.9 kN and rolled at an optimum radius of 100 mm. The critical modal shape of the disc was a shape with two nodal diameters, and the associated natural frequency increased by 8.66% after prestressing. |
