PSI - Issue 64

Lingzhen Li et al. / Procedia Structural Integrity 64 (2024) 1318–1325 Author name / Structural Integrity Procedia 00 (2019) 000–000

1323

6

Bond length: 300 mm

1.4 or 0 1.5 mm 0.5 mm

F

Adherent strip Adhesive

Steel plate

10 mm

(a) Dimensions of lap-shear joints (adherent strips are 50 mm wide).

(b) Stress-strain curves of adherent strips.

Fig. 4. Schematic view of lap-shear joints with various adherents.

5.2. Fe-SMA vs. CFRP lap-shear joints The following phenomena of lap-shear tests were reported by Li et al. (Li et al., 2023b): (i) when the same linear adhesive is used as the bonding agent, the CFRP and Fe-SMA lap-shear joints share nearly identical bond capacities; (ii) when the same nonlinear adhesive is used as the bonding agent, the CFRP joint has approximately twice the bond capacity as that of the Fe-SMA joint. Here Fe-SMA refers to the non-prestrained Fe-SMA, whose chord modulus (153.3 GPa) is nearly identical to the E-modulus of CFRP (156 GPa). These phenomena can be quantitatively explained by the proposed Wine Glass model.

(a) Bonded by a linear adhesive (SikaDur 30). Tensile stress demonstrated up to 1000 MPa.

(b) Bonded by a nonlinear adhesive (SikaPower 1277). Tensile stress demonstrated up to 2000 MPa.

Fig. 5. Bond capacities of non-prestrained Fe-SMA joints and CFRP joints. The footnotes "NS" and "CFRP" represent non-prestrained Fe-SMA joints and CFRP joints, respectively.

The fracture energy of the linear adhesive is insufficient to induce the nonlinear behaviour of the Fe-SMA strip. As a result, both the CFRP wine glass (the black curve in Fig. 5 (a)) and Fe-SMA wine glass (the red curve in Figure Fig. 5 (a)) exhibit similar profiles, resulting in comparable tensile stress levels (height of the wine). Compared against the Fe-SMA joint, the CFRP joint has a marginally higher tensile stress and a slightly smaller cross-sectional area. Consequently, bond capacities of both CFRP and Fe-SMA joints are nearly identical.