PSI - Issue 60

Ashish Kumar et al. / Procedia Structural Integrity 60 (2024) 364–371

368

/ Structural Integrity Procedia 00 (2019) 000–000 5

A. Kumar, Y.V.N. Bhat, S.Patri, P.A.Kumar, S.I.S.Raj, A. Kumar, Y.V.N. Bhat, S.Patri, P.A.Kumar, S.I.S.Raj, S.S.Kumar, B.K.Sreedhar / Structural Integrity Procedia 00 (

Fig. 7. Experimental result: Frequency & Phase response from OGT obtained by exciting IGT

Fig. 8. Experimental result: Frequency & Phase response from OGT obtained by exciting OGT

5. Additional analyses to understand experimental results understand experimental results

The measured values under both configurations did not match the individual natural frequency of IGT or OGT, thus indicating the existence of proper connections between them. As a result of these connections, the combined system’s mass and stiffness properties changed in both cases to various degrees. tem’s mass and stiffness properties changed in both cases to various degrees.

5.1. Analysis to understand first set of experimental results

A combined model was used to understand the behaviour of connected IGT and OGT. The two remain connected at the top flange and the two O-ring locations. These connections were simulated in the FE model as discussed below. i Top flange connection between IGT and OGT was simulated using body to body fixed connections, which restricts all relative displacements and rotations ii Connections between the two, near the O connections, which restricts only displacements and allows rotational DOF between the connected bodies. Apart from these connections, OGT was fixed at the two weld locations and IGT was supported at seven lateral support locations. With these BCs, the first six natural frequencies of the system were estimated to be 15.9 Hz, 32.26 Hz, 35.50 Hz, 44.49 Hz, 49.52 Hz, and 50.37 Hz. The BC an top portions of the assembly in figure 9 are zoomed in to clearly see the mode shape of both IGT and OGT at that location. It can be observed from the figure that in the first three modes, IGT alone vi modes, both IGT and OGT vibrate together. The fourth mode shape, in which both IGT and OGT participate, occurs at a frequency of 44.4 Hz, which is in close agreement with the measured value of 44.2 Hz. This study hence confirms that the measured natural frequency of 44. 2 Hz corresponds to the combined IGT & OGT assembly. ring locations. These connections were simulated in the FE model as discussed which restricts all relative displacements and rotations w.r.t. each other, and Connections between the two, near the O-ring locations were established using body to body hinged OGT was fixed at the two weld locations and IGT was supported at seven lateral Hz, 35.50 Hz, 44.49 Hz, 49.52 Hz, and 50.37 Hz. The BC and mode shapes for this case are shown in 9 are zoomed in to clearly see the mode shape of both IGT and OGT at that igure that in the first three modes, IGT alone vibrates, while in the remaining ms that the measured natural frequency of 44. 2 Hz corresponds to the combined IGT & OGT assembly. ring locations were established using body to body hinged d mode shapes for this case are shown in figure 9. The brates, while in the remaining