A graphical solution to bond capacity

Abstract

This study proposes an analytical model, referred to as the "Wine Glass model", offering an elegant graphical solution to the bond capacity. It is built on the basis of two key assumptions: (i) the bond length is sufficiently long (longer than an effective bond length) and (ii) the stress-strain behavior of the adherent monotonically increases, which is typically met by the majority of engineering materials. The tensile stress-strain (σ - ϵ) curve of the adherent can be visualized as a wine glass when plotted against the vertical axis (σ-axis). In this analogy, the fracture energy of the adhesive bond divided by the thickness of the adherent strip (Gf/t) represents the wine poured into the glass. The height of the wine within the glass corresponds to the level of adherent tensile stress, with respect to the bond capacity (Fb). This Wine Glass model, which suits lap-shear joints with both linear and nonlinear adherents, is validated on experimentally measured bond capacities of various types of lap-shear joints, including carbon fiber reinforced polymer (CFRP)-to-steel joints and iron-based shape memory alloy (Fe-SMA)-to-steel joints. It unveils the mechanism of bond capacity.