PSI - Issue 61

Ahmet Çevik et al. / Procedia Structural Integrity 61 (2024) 291–299

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Cevik et al. / Structural Integrity Procedia 00 (2019) 000 – 000

(a) (b) Fig. 2. (a) FEA Model created to apply to pure shear loading, (b) the load-displacement data obtained from four different fixtures and finite element analysis.

Four different loading fixtures shown in Figure 3 are used to apply pure shear loading to the plexiglass curved beam utilizing a Shimadzu electro-mechanical tensile testing machine. The load-displacement data obtained from each loading fixture are shown in Figure 2b. In loading fixture A, the lower arm of the curved specimen is clamped via a bolt, while shear force is applied to the upper arm with a line contact, allowing this arm to be free of moment. The movement of the contact line, however, leads to small force drops attributed to stick-slip frictional sliding, in addition to the non-linear force-displacement curve. In loading fixture B, the load is applied with a cylindrical roller instead of a contact line mechanism. The cylindrical roller is free to rotate to remove the stick-slip slippage of the contact line. Although this loading fixture does not result in small force drops, the force-displacement curve shows more non-linear behavior. In loading fixture C, the cylindrical roller is bolted to the upper arm of the specimen to eliminate this non-linear behavior shown in the load-displacement data. This loading fixture is identical to that used in Martin and Jackson (1993). The force-displacement curve of this loading fixture matches the reference finite element result up to a displacement of 3mm, then starts deviating. This deviation is attributed to the stiffening effect due to the combined application of axial load and transverse load since the loading fixture has a fixed base. To eliminate this stiffening effect, the fixed base of the loading fixture is replaced with the sliding base shown in loading fixture D. This change results in a softening effect on the load displacement curve, leading to a good agreement with the reference load-displacement data.

Fig. 3. Experimental loading fixtures designed to apply shear loading: (A) fixed base with contact loading, (B) fixed base with pin loading, (C) fixed base with bolted pin loading, (D) sliding base on rail with bolted pin loading.