M.J Kokabi - PhD, Department of Mechanical Engineering, University of Semnan, Semnan, Iran
H Jamshidi - PhD student, Department of Mechanical Engineering, Iran University of Science and Technology, Tehran, Iran
F Meisami - PhD student, Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

Flange couplings have a lot of application in the industries. So, studying dynamic behavior of this type ofjunctions would be necessary. In this study, dynamic model of a system of two beams and a flange coupling has beenextracted. The flange has been modeled as a torsional equivalent spring which is connected two beams. After that, aprocedure has been presented in order to calculate the stiffness of the torsional spring. The equivalent torsionalstiffness was calculated by using tensional stiffness of joint (summation of stiffness of bolt and flange laps). Then, asummation of equivalent stiffness over all bolts was done. Having full dynamical equation, the main subject of the studywhich is the scaling, is investigated. An appropriate procedure has been introduced for scaling of flange couplingparameters. In order to examine the indefinite parameters and verify the results of previous calculations, anexperimental setup was developed. The setup consists of two separate 1.7 and 2 meters pipes connecting each other witha 9-bolted flange. A scaled model with the proportion of 1/3 was also made and examined. In the scaled model thenumber of bolts was reduced to 6 in order to evaluate the proposed scaling procedure. Results of modal testing consistof frequency response function and natural frequencies were extracted. Then a comparison has done between theresults of the prototype and scaled model. Result of the scaled model and prototype had good agreement and percent oferror remains very low.

Natural frequency, Scaling, Flange coupling, Modal test