Analiza vplivov geometrijskih odstopanj na silo v vijačni zvezi

Rak, Andrej (author), Halilovič, Miroslav (mentor)

V prirobnični zvezi se med izdelovalnim procesom pojavijo geometrijske imperfekcije ravnosti. Slednje vplivajo na povečanje sil v vijačni zvezi in cevasti strukturi, kar vpliva na nastanek utrujenostnih poškodb. Opazovane prirobnične zveze so povezovalni elementi med mobilnim in statičnim delom žerjava in so spojene z vijačno zvezo. V dotičnem primeru so bile analizirane različne velikosti in oblike geometrijskih imperfekcij ravnosti na stičnih ploskvah prirobnične zveze. Hkrati so bili opazovani tudi vplivi in posledice geometrijskih imperfekcij ravnosti na komponente prirobnične zveze. Za izvedbo analize je bil zgrajen model MKE, in sicer ob upoštevanju obstoječih standardov in smernic (npr. German DIBt, ISO 7090, VDI 2230 itd.). Z namensko zgrajeno programsko kodo so bile simulirane različne oblike geometrijskih imperfekcij. Ugotovljeno je bilo, da se sila na območju geometrijske imperfekcije v vijaku poveča neodvisno od njene oblike in velikosti. Zunanja sila na prirobnično zvezo se med vijaki ne prerazporedi več enakomerno kot v primeru idealne prirobnice. Obravnavni postopek omogoča določitev zgornjih mej pri določanju dopustnih geometrijskih imperfekcij.

• Language: Slovenian
• Keywords: prirobnična zveza, vijačna zveza, geometrijska imperfekcija ravnosti, žerjavi, vetrne turbine, MKE, sile v vijačni zvezi, utrujenostne poškodbe
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FS - Faculty of Mechanical Engineering
• Place of publishing: Ljubljana
• Publisher: [A. Rak]
• Year: 2020
• Number of pages: XXIV, 86 str.
• PID: 20.500.12556/RUL-121816
• UDC: 621.882:531.211:519.61(043.2)
• COBISS.SI-ID: 39068931
• Publication date in RUL: 31.10.2020

Secondary language

• Language: English
• Title: Analysis of geometric deviations on the force in bolt connection

Abstract

In the flange connection, geometric imperfections of flatness appear during the manufacturing process. They affect the increase of forces in the bolt connection and tubular structure, which negatively affect the occurrence of fatigue fractures. To perform the analysis, an FEM model was built taking into account existing standards and guidelines (e.g. German DIBt, ISO 7090, VDI 2230, etc.). Various forms of geometric imperfections were simulated with purpose-built code. It was found that the force in the bolt in the area of geometric imperfection increases regardless of its shape and size. The external force on the flange connection is no longer redistributed evenly between the bolts as in the case of an ideal flange. At the same time, the sum of all forces in the bolts with the geometric imperfection on the flange included is equal to the external force. Procedure under consideration makes it possible to set upper limits in determining the permissible geometric imperfections.

• Keywords: flange connection, bolt connection, geometric imperfection of flatness, cranes, wind turbines, FME, nonlinear solution, forces in bolt connection, fatigue