Condition monitoring of crack extension in the reinforcement adhesive joints by carbon nanotubes

Abstract


 
 
 Carbon nanotubes (CNT) are ideally suited to be employed for damage sensing in fiber rein- forced composite structures. In this work, the capability of CNTs for crack extension of a single lap Al-Al adhesive joints (SLJ) under shear load is studied using electrical resistance change. Different weight per- cent of CNT are added to epoxy adhesive. Epoxy adhesive with high concentration of CNT is obtained during shear loading to have the maximum strength and provide the best sensory properties. To provide a more concise evaluation of the crack extension in the adhesive layer under shear load, artificial defects are embedded into the SLJ specimens. The effects of square and circular defects with two different sizes on the crack extension in the adhesive layer are evaluated. The results showed that the maximum relative resistance change has occurred by 220% when the microcracks are initiated and accordingly developed from the nanoadhesive and changed its direction from the Square defect boundary. Additionally, in comparison with interface fracture in defective adhesive joint, when a part of crack grows through the adhesive layer, the resistance change showed higher values.
 
 

Study of Hybrid Composite Joints with Thin-Ply-Reinforced Adherends

“…This results in the onset of delamination, which can lead to the rapid degradation of the mechanical performance of the structure and cause premature failure [9][10][11][12]. Accordingly, multiple studies have investigated methods for adhesive layer modification [13,14] or composite laminate modification to delay delamination in a composite joint [15][16][17], such as the use of fibre metal laminates (FML), composite laminates with toughened layers [18,19], glass fabric reinforcement [20], the use of Z-pins [21,22], 3D weaving [23], stitching [23], braiding [24], or even the adoption of additional thermoplastic inter-plies [25]. However, the significant complexity of these techniques often restricts their usage.…”

Damage Characteristics of a Step Lap Joint Exposed to Flexural Loading for Its Different Configurations

“…The contact between the adherends and the punch was modelled using the surface-to-surface contact method with the penalty algorithm and the hard contact model. The goal of this paper is to elucidate the complex failure process of the adhesive layer in stepped lap joints in different configurations under bending loading [14][15][16].…”

Evaluation of XD 10 Polyamide Electrospun Nanofibers to Improve Mode I Fracture Toughness for Epoxy Adhesive Film Bonded Joints

“…However, it is crucial to develop a strong interfacial adhesion to correctly transfer the load from the polymeric matrix to the nano-reinforcement [13]. Carbon-based nanoparticles, such as carbon nanofibers (CNFs), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are widely used for this purpose [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. These nanoparticles enhance the fatigue life of bonded joints and can be used for damage detection, as they also improve the electrical properties of the resin they are dispersed in [29][30][31][32][33][34][35][36][37][38][39].…”

“…Carbon-based nanoparticles, such as carbon nanofibers (CNFs), carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), are widely used for this purpose [25][26][27][28][29][30][31][32][33][34][35][36][37][38][39]. These nanoparticles enhance the fatigue life of bonded joints and can be used for damage detection, as they also improve the electrical properties of the resin they are dispersed in [29][30][31][32][33][34][35][36][37][38][39]. Recently, studies have shown that the application of hybrid nanoparticles is a viable approach to designing tougher, stronger and more durable bonded joints [40][41][42][43][44].…”