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Abstract

An analysis is presented for the fracture of an adhesively bonded double-cantilever beam that fails with extensive plastic deformation of the adherends. The analysis permits a value for the toughness of the joint to be distinguished from the energy absorbed by the plastic deformation. Specifically, this value for toughness can be determined from post-fracture observations of the deformation and from a knowledge of the constitutive properties of the adherends. The analysis has been used to determine experimentally the toughness of plastically deforming joints formed using three different adhesives to bond a series of different thicknesses of aluminium and steel. In each case, it was found that, despite large differences in the extent of deformation, the value for toughness was dependent only on the materials used to form the joint. The toughness was independent of the thickness of the adherends.

On the Use of a Driven Wedge Test to Acquire Dynamic Fracture Energies of Bonded Beam Specimens

“…Interests in bonding of thin metal adherends of relevance to the automotive industry have driven the development and adoption of several wedge tests that induce large plastic bending of the adherends. Knowing the radius of curvature of the debonded adherends and the elastic-plastic properties of the adherends, one can calculate the fracture energy of the adhesive either statically [28] or for dynamically loaded specimens such as the impact wedge peel (IWP) test [29].…”

Stress analysis at the interface of metal-to-metal adhesively bonded joints subjected to 4-point bending: Finite element method

“…The higher stress state along OC observed in all the simulations was probably because of two reasons: (a) OC is the upper interface (between the upper adherend and the adhesive), and (b) the upper adherend thickness is 1/3 rd of the lower adherend thickness and hence has undergone higher degree of plastic deformation which increases the degree of stress along the upper interface [13].…”

“…The adherends are known to have a constraining effect on the adhesive layer which is dependent on the modulus mis-match between the adherends and the adhesive and the adhesive thickness [13][14][15][16]. [10,15,17].…”

“…At lower thicknesses, the constraint of the adherends prevents the adhesive from straining to relieve the A c c e p t e d M a n u s c r i p t 15 stress from the high load-concentration point [16]. However, at higher thicknesses, restraint decreases, distributing the stress [13,18]. A similar observation has been made by Xu et al [19] that the increase in thickness increases the toughness by increasing the size of the plastic zone.…”

Quasi‐Static Fracture Tests

“…Category II configurations of the T-peel test are addressed by [144][145][146][147] and in Section 3.15, where either analytical or numerical procedures are used to subtract the calculated plastic dissipation from the measured peel energy, resulting in the extraction of a meaningful fracture energy -one that has even been shown to compare favorably with results from tapered DCB specimen fracture tests and properly analyzed 90 • peel tests [144]. Category III geometries have been addressed by others [148][149][150][151]. A key point is simply that when plastic work is performed on the adherends, the forces required to propagate debonding will necessarily be higher to reflect this increased energy dissipation per unit of debond propagation area.…”