Impact Fatigue Life of Adhesively Bonded Composite-Steel Joints Enhanced with the Bi-Adhesive Technique

Abstract

One of the most common loading conditions that bonded joints experience in service is repeated impact. Despite the destructive effects of impact fatigue, the behavior of metal-composite bonded joints subjected to repeated impact loads has rarely been studied in the literature. Therefore, it is of utmost importance to pay attention to this phenomenon on the one hand and to find solutions to improve the impact fatigue life of bonded composite metal components on the other hand. Accordingly, in this study, the use of the bi-adhesive technique is proposed to improve the durability of composite-metal single-lap joints (SLJs) under impact fatigue loading conditions. J-N (energy-life) method is also used to analyze the experimental data obtained. Accordingly, in the present study, the impact fatigue behavior of single adhesive metal to composite joints was analyzed experimentally based on the J-N method and also numerically using the finite element method (FEM). By using two adhesives along a single overlap, the impact fatigue life of joints between dissimilar composite and metal joints was also analyzed experimentally. The results show that the double adhesives technique can significantly improve the impact fatigue life of the tested joints. It was also found that the optimum length ratio of the adhesives (the length covered by the ductile adhesive relative to the total overlap size) is a function of the stiffness of the joint and is more pronounced for less stiff bonded joints. A linear elastic numerical analysis was also conducted to evaluate the stress state along the bloodline of the bonded joints. Results show that the compressive peel stress made at the boundary of the two adhesives can be a possible reason behind the different results observed.

Delamination prevention of composite joints with asymmetric carbon-fiber reinforced plastic adherends

“…This has led to the widespread adoption of composite materials, such as carbon fiber reinforced plastics (CFRP), which offer superior specific stiffness, excellent strength-toweight ratios, and reduced overall weight. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Alongside composite materials, adhesive bonding has emerged as a promising alternative joining method, offering the potential for improved weight efficiency and joint performance. [15][16][17][18][19] Despite these benefits, the aviation industry has been slow to adopt adhesive bonding for primary aircraft structures due to concerns related to non-destructive testing limitations and occurrence of delamination, due to high peel stresses.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Alongside composite materials, adhesive bonding has emerged as a promising alternative joining method, offering the potential for improved weight efficiency and joint performance. [15][16][17][18][19] Despite these benefits, the aviation industry has been slow to adopt adhesive bonding for primary aircraft structures due to concerns related to non-destructive testing limitations and occurrence of delamination, due to high peel stresses. 20 Therefore, while adhesive bonding has found some applications, overcoming these notable challenges is imperative for its wider acceptance within the aeronautical industry.…”

Use of intumescent flame-retardant systems in epoxy adhesives for debonding purpose

“…This process eliminates the need for the additional components typically used in classical methods, such as screws. Indeed, the adhesive joints exhibit increased resilience to application stresses, thereby conveying superior fatigue resistance and an extended fatigue life [ 4 , 5 ]. The employment of lighter materials in this process addresses a critical environmental concern, since the reduction in the overall weight of the finished products results in a significant in carbon footprint decrease, due to lower energy consumption during both manufacturing and use [ 6 ].…”

A comparative study of the effect of various surface treatments on the fracture behavior of aluminum adhesive joints under mode I loading

“…On the other hand, adhesive joints offer advantages such as uniform stress distribution, enhanced fatigue resistance, reduced structural weight, and the ability to join dissimilar materials. [2,3]. The factors mentioned above make adhesive joints highly appealing as a valuable and signi cant method in industries such as aviation, marine, and automotive.…”