PSI - Issue 21

140 B. Paygozar et al. / Procedia Structural Integrity 21 (2019) 138–145 B. Paygozar, S.A. Dizaji / Structural Integrity Procedia 00 (2019) 000 – 000 3 ∅ 265 and ∅ 400 in diameters as the inner and outer parts. In addition, two symmetrical gaps between the handle and two sides of the inner tube were taken as 15 mm in the study. The size of the gap is calculated according to SAC (FEMA-355D, 2000) to set the appropriate time of the engagement for the inner tube. The Young’s modulus and Poisson’s ratio of the steel were taken as 200 GPa and 0.3, respectively. Plastic properties of the material, true stress and corresponding true plastic strain, were summarized in Table 1. Figures 2a and 2b indicate a comparison between experimental and corresponding numerical results. The experimental work was carried out under displacement controlled loading condition for the sake of simplicity. But in the numerical investigations, the loading pattern of SAC (FEMA-355D, 2000) was utilized, at which the increase in the drift angle (θ) was changed to increase in the displacements accordingly (see Fig. 3).

(a) (b) Fig. 1. The structure of the system. a) Experimental setup (Alavighi, 2017), b) A general configuration used in the numerical simulations indicating the components of the structures along with the boundary conditions.

Table 1. Plastic properties of the material used. Property

Quantity

True stress (MPa)

300

320

340

365

385

390

True plastic strain (mm/mm)

0

0.001

0.008

0.048

0.148

0.248

(a) (b) Fig. 2 Validation of the numerical study. a) Experimental outputs, b) Numerical results for the setup. The loading condition for validation was displacement-controlled.