The Effect of CO₂ Laser‐Induced Microhole Formations on Adhesive Bonding Strength of CFRP/CFRP Joints

Abstract

There are many different techniques to improve the adhesion between carbon fiber‐reinforced plastics (CFRP) which are used in aircraft primary structures. One of the most common techniques is the specific surface structuring of the joining parts in order to obtain mechanical interlocking. In this study, laser‐induced surface structuring effect on adhesion strength of CFRP/CFRP joints was investigated by single lap shear tests. Microholes were created by CO2 laser with different configurations in x and y axis for the best mechanical interlocking effect on adhesive bonding. The effects of microhole numbers (309, 625, and 914) and microhole formations (triangle, inverted triangle, frame, and box) on the adhesive bonding strength of the CFRP/CFRP joints were determined by using single lap shear tests according to ASTM D5868‐01 standard with 60 kN DARTEC universal test machine. Single lap shear tests showed that microhole structuring has a significant effect on mechanical interlocking for adhesive bonding of CFRP/CFRP joints. Results showed that the shear strength of CFRP/CFRP joints improved at 309 microholes and frame type microhole formations. After mechanical tests, damage mechanisms were observed by using the optical microscope. POLYM. COMPOS., 40:2891–2900, 2019. © 2018 Society of Plastics Engineers

Experimental probe into the femtosecond laser ablation thresholds in carbon fiber reinforced polymer and assessment of the measurement theories

“…26 Besides the simultaneous removal by femtosecond laser cutting of CFRP, the selective removal by femtosecond laser surface treatment is also widely applied for enhanced performance of structural adhesive bonding, 20,27,28 which requires the resin matrix getting removed with the keeping of carbon fiber. 20,28 In this case, the laser fluence should be higher than F th of resin matrix and lower than F th of carbon fiber. Consequently, to accurately determine F th of resin matrix and carbon fiber in CFRP becomes the key point in both the femtosecond laser cutting and surface treatment of CFRP.…”

Epoxy-Modified Bismaleimide Structural Adhesive Film Toughened Synergistically with PEK-C and Core–Shell Polymers for Bonding CFRP

“…In addition, the influence of the composite material surface treatment on bonded joint performance is also important [ 27 , 28 , 29 ]. Surface treatment of the composite material was implemented by Bora [ 30 ] using a CO 2 laser, which created micro-holes on the surface of the CFRP, thereby improving the mechanical interlocking effect on adhesive bonding and the bonding strength of the CFRP joints. Bello et al [ 14 ] studied the fatigue crack growth in laser-treated, adhesively bonded composite joints, and their results show that uniform laser treatment increases the fatigue limit of the joints.…”

Study on anisotropic heat transfer and thermal damage in nanosecond pulsed laser processing of CFRP

“…1,2 Achieving high-quality connections in carbon composite parts during assembly is always a challenging task. 3 Machining of holes or channels in CFRP parts by bolting or adhesive bonding techniques to meet the assembly needs of the engineering applications. 4,5 However, the CFRP plate is composed of epoxy resin and carbon fiber, which have the characteristics of anisotropy and inhomogeneous in heat transfer.…”

“…Carbon fiber reinforced plastic (CFRP) is being widely used in the manufacturing field of aviation, medical, railway vehicles, and auto industries due to its excellent mechanical properties, high specific stiffness, and corrosion resistance 1,2 . Achieving high‐quality connections in carbon composite parts during assembly is always a challenging task 3 . Machining of holes or channels in CFRP parts by bolting or adhesive bonding techniques to meet the assembly needs of the engineering applications 4,5 .…”