PSI - Issue 60

Ashish Kumar et al. / Procedia Structural Integrity 60 (2024) 364–371 A. Kumar, Y.V.N. Bhat, S.Patri, P.A.Kumar, S.I.S.Raj, S.S.Kumar, B.K.Sreedhar / StructuralIntegrity Procedia 00 ( A. Kumar, Y.V.N. Bhat, S.Patri, P.A.Kumar, S.I.S.Raj,

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/ StructuralIntegrity Procedia 00 (2019) 000–000

4. Experimental Studies

The first set of experiments was conducted by mounting accelerometers on OGT and IGT near the top accessible portion of the assembly, as shown in figure experiment proved inconclusive towards concluding the number of supports acting on IGT, as discussed in section 4.1. Therefore a modified experimental setup, as shown in figure 3, using impulse hammer excitation. However, the results of this concluding the number of supports acting on IGT, as discussed in section 4.1. Therefore a modified experimental setup, as shown in figure 4, was used for repeated experiments. 3, using impulse hammer excitation. However, the results of this 4, was used for repeated experiments.

4.1. Experimental results, observations and repeated experiments results, observations and repeated experiments

Comparison of natural frequencies to decide upon the state of supports on IGT required measurement of distinct natural frequencies of IGT and OGT. However, an identical response peaking at 44.2 Hz was obtained from both, regardless of the location of impulse excitation. The frequency and phase response spectrum obtained from the experiment are shown in Figs. 5-8 and are summarised in Table 1. se excitation. The frequency and phase response spectrum obtained from the 8 and are summarised in Table 1.

Table 1. Results of first set of experiments. Sl. No Excitation location 1 IGT

Response location

Natural frequency (Hz)

IGT

44.2

2

IGT

OGT

44.2

3

OGT

IGT

44.2

4

OGT

OGT

44.2

A common natural frequency for IGT and OGT indicates that both are connected as a single entity. Experiments were repeated after removing connections between the two by raising IGT by 60 mm, as shown in the natural frequency of only IGT. However, experiments with this modified setup also yielded a common natural frequency under all combinations of excitations and responses from IGT and OGT. The value of natural frequency in this case was 33 Hz. Hence, further analyses using the FE method experimental results, as discussed in the following sections. . However, experiments with this modified setup also yielded a common natural in this case was 33 Hz. Hence, further analyses using the FE method were carried out to understand these peculiar were repeated after removing connections between the two by raising IGT by 60 mm, as shown in figure 4, to obtain were carried out to understand these peculiar

Fig. 5. Experimental result: Frequency & Phase response from IGT obtained by exciting IGT

Fig. 6. Experimental result: Frequency & Phase re obtained by exciting OGT Fig. 6. Experimental result: Frequency & Phase response from IGT