PSI - Issue 64

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

1319

2

Nomenclature Adherent tensile stress Adherent tensile stress with respect to bond capacity Adherent tensile stress at Adherent tensile strain Adherent tensile strain at Shear stress in the bond line Adherent E-modulus Bond capacity

Fracture energy of the adhesive bond , Partial fracture energy at slip Slip of adherent strip Slip of adherent strip at Ultimate slip Adherent strip thickness Coordinate in the loading direction A random location in the bond line

1. Introduction Modern structures often comprise composite components, including reinforced concrete (RC) structures and fiber reinforced composite (FRP) structures. These components can be abstracted as reinforcing/strengthening rebars/strips/fibers bonded onto/into substrates. Extensive experimental observations, such as Refs. (Cruz et al., 2020; Zheng and Dawood, 2017), highlighted that debonding between adherents and substrates is a typical failure mode. Therefore, understanding bond behavior is crucial for ensuring the integrity and longevity of these structures. Bond capacity is a fundamental and crucial aspect of bond behavior. Over the past 2-3 decades, FRP materials have undergone extensive investigations as reinforcing/strengthening materials. Carbon FRP (CFRP), in particular, has attracted significant attention. During this period, models have been well-established for FRP bonded joints comprising linear and nonlinear adhesives (Fernando et al., 2014; Xia and Teng, 2005). Recently, bonded shape memory alloys (SMAs) have emerged as an innovative solution for reinforcement and strengthening, where the prestress can be applied through a heating and cooling process (Li et al., 2020; Zheng and Dawood, 2017). Among SMAs, iron-based SMAs (Fe-SMAs) stand out due to their affordability and appreciate prestress level (Cladera et al., 2014; Gu et al., 2021). Nevertheless, the nonlinear stress-strain behavior of Fe-SMA poses challenges in analyzing the bond behavior of Fe-SMAs (Li et al., 2023b; Wang et al., 2021). This study proposes an analytical model, referred to as the “Wine Glass model”, featuring an elegant graphical solution, to accurately estimate the bond capacity of lap-shear joints. It accommodates both linear and nonlinear adherents, as well as linear and nonlinear adhesives. 2. Model setup

=0 , = 0 , and =0

= , = , and =

(a)

x

F

Adherent strip Adhesive

Substrate

+

(b)

Adherent element

Fig. 1. (a) Schematic view of a lap-shear joint; (b) the equilibrium of an adherent infinitesimal element.

Fig. 1 (a) shows a general lap-shear joint, with the bond length assumed to be sufficiently long. This ensures that the load acting on the right end does not induce shear deformation at the left (free) end. In practical terms, a bond