PSI - Issue 44

Masoud Pourmasoud et al. / Procedia Structural Integrity 44 (2023) 590–597 M. Pourmasoud et al. / Structural Integrity Procedia 00 (2022) 000–000

594

5

Fig. 3 presents the yield strengths from each test carried out on three isolators as the samples. The comparison between the results shows similar trend between the tests and the proposed equation which provide designers estimating the yield strength of the lead rubber bearing at any level of shear strain and axial load. for majority of tests, the yield strength from the tests have been fallen with ±5% of the yield strength extracted from the test. In addition, it shall be noted that, there is no guaranty that the tests’ results from two identical isolator give rise to the same numbers. It is because, the rubber is made from a natural material which its specification is not absolute and has an influential impact on the confinement of the lead core. So, even in practice a partial difference between the results of two identical isolators are quite likely.

a

Isolator 1

12.00

10.00

8.00

6.00

4.00

2.00

Yield strength (MPa)

0.00

PT-4

PT-5

PT-8

PT-9

PT-12

PT-13

σ y - result

7.93

8.57

8.43

9.78

6.37

7.45

σ y - Equation 7.09

7.46

8.10

9.02

6.42

6.48

Test number

b

Isolator 5

10.00

8.00

6.00

4.00

2.00

0.00

PT-8

PT-9

PT-12

PT-13

Yield strength (MPa)

σ y - result

7.20

8.03

8.18

9.34

σ y - Equation

7.87

8.27

9.74

10.79

Test number

c

Isolator 7

8.00

6.00

4.00

2.00

0.00

Yield strength (MPa)

PT-4 PT-5a PT-5b PT-5c PT-5d PT-8 PT-9 PT-12 PT-13

σ y - result

6.24 7.44 7.35 7.42 7.49 6.85 7.85 5.04 6.18 σ y - Equation 6.94 7.08 7.02 7.19 7.36 7.33 7.58 6.55 6.59

Test number

Fig. 3. Yield strength comparison between the prototype tests and the proposed equation. (a)Isolator 1; (b) Isolator 5; (c) Isolator 7.