Fracture energy assessment of adhesives – Part I: Is G_IC an adhesive property? A neural network analysis

Abstract

Different joint types and geometries have been considered to measure the fracture toughness ( Gc) of adhesives. However, results show that, sometimes, the obtained Gc values for the same adhesives are not similar in different reports. Several factors including the joints geometry, material properties of the substrate, and also the test conditions influence the obtained results. This study is conducted to find a logical connection between these factors and to find their influences on the obtained mode I fracture toughness ( GIc) to understand which parameters are the most influential and which ones are less significant. To this aim, 115 values of different GIcalready reported in the literature were collected and examined regarding the geometrical and material parameters. To find the rational relationship between the effective parameters and the reported GIcvalues, a method based on the artificial neural network technique was employed. The results revealed that whilst the fracture energy of aluminum adhesive joints is more influenced by geometrical parameters including the joint type and substrate thickness, the steel adhesive joints are more sensitive to the adhesive properties and bondline thickness. With this study, it is possible to design an optimum test by minimizing the effects of variables that cause errors in obtaining fracture toughness and also to estimate GIc of adhesives by using the developed model. On the other hand, it is also possible to design real structures in which the fracture toughness of the adhesive reaches its maximum value.

Development of a Unified Specimen for Adhesive Characterization—Part 2: Experimental Study on the Mode I (mDCB) and II (ELS) Fracture Components

“…However, recent studies by Akhavan-Safar et al [ 3 ], for mode I specimens, and Delzendehrooy et al [ 4 ], for mode II loading, have shown otherwise. G C might not be fully independent of the geometry and mechanical characteristics of the specimen.…”

Influence of cyclic aging on adhesive mode mixity in dissimilar composite/metal double cantilever beam joints

“…One of the fundamental issues for fracture analysis in adhesive joints is the concept of fracture energies [7][8][9][10][11]. Previous scientists proposed double cantilever beam (DCB) specimens with similar substrates for calculation of the mode I fracture energy of adhesive [12,13].…”

“…[3][4][5][6] One of the fundamental issues for fracture analysis in adhesive joints is the concept of fracture energies. [7][8][9][10][11] Previous scientists proposed double cantilever beam (DCB) specimens with similar substrates for calculation of the mode I fracture energy of adhesive. 12,13 The difference in the material substrate fatigue and fracture behaviour of adhesive joints made from dissimilar adherends is more complex in comparison to adhesive joints made from similar adherends.…”

The interaction of loading mode and humidity on the properties degradation of an epoxy adhesive subjected to strength, fracture, and fatigue tests

“…The fracture toughness is an important material property that must be taken into account when studying an adhesive's performance 14,15 . The effect of aging on this property has also been investigated in multiple researches.…”

“…The fracture toughness is an important material property that must be taken into account when studying an adhesive's performance. 14,15 The effect of aging on this property has also been investigated in multiple researches. Sugiman et al 16 studied the effect of aging on the mode II fracture toughness, concluding it increases on a first stage until the water content on the adhesive reaches 1.8% and, after that, it starts decreasing.…”