Laser-based surface patterning of composite plates for improved secondary adhesive bonding

Tao, Ran; Alfano, Marco; Lubineau, Gilles

doi:10.1016/j.compositesa.2018.02.041

Cited by 74 publications

(48 citation statements)

References 30 publications

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“…This can generate a micro-mechanical interlocking between materials (Ref 23). The surface profile of materials has been identified as one of the key parameters to enhance the mechanical interlocking in the joining of composites (Ref 44,45). Therefore, with the fluted pin, the features at the interface of joints can create efficient mechanical interlocking mechanisms between the materials that increases the lap shear Figure 8 shows the typical force-displacement curves for the lap shear tests of the joints manufactured by the flat and fluted pins for the 1.25 mm plunge depth.…”

Section: Performance Of the Jointsmentioning

confidence: 99%

A New Design for Friction Stir Spot Joining of Al Alloys and Carbon Fiber-Reinforced Composites

Bolouri

Fotouhi

Moseley

2020

J. of Materi Eng and Perform

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Friction stir spot welding (FSSW) has been recently developed to join dissimilar materials. However, the traditional requirement for a rotating tool consists of a pin and shoulder in FSSW leads to a complex joining process and unpredictable defects. In this study, a new static-shoulder design in FSSW was proposed and developed to join Al alloys to carbon fiber-reinforced polymer (CFRP) composites. The main joining parameters, including pin rotational speed, pin feed rate and pin plunge depth, were varied to investigate their effects on the joining temperature, materials interaction and the strength of joints. The pin rotational speed had the largest influence on the joining temperature. Lap shear tensile testing was conducted to evaluate the performance of the joints. The joints exhibited the ultimate lap shear force from 230 to 260 N. A brittle fracture occurred with the displacement-at-fracture load of 0.35-0.41 mm. Cross-sectional images revealed the creation of undulations on the surface of Al alloys in the joining zone. The undulations created a macro-mechanical interlocking bonding between the materials, which determined the performance of the joints. For a flat pin, by increasing the plunge depth from 1.25 to 1.30 mm, the undulation size increased from 0.21 to 0.26 mm, which can enhance the macro-mechanical interlocking bonding between Al alloys and CFRP and accordingly increased the ultimate shear force of the joints from 230 to 241 N. Use of a fluted pin significantly influenced the flow of the plasticized Al alloy which created pronounced undulations and large Al alloy spikes of 0.46 mm. These features seemed to establish an efficient macro-mechanical interlocking bonding, which resulted in a noticeable improvement in the performance of the joint. For a plunge depth of 1.30 mm, the ultimate shear force increased to 261 N using the fluted pin.

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Section: Performance Of the Jointsmentioning

confidence: 99%

A New Design for Friction Stir Spot Joining of Al Alloys and Carbon Fiber-Reinforced Composites

Bolouri

Fotouhi

Moseley

2020

J. of Materi Eng and Perform

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“…As contaminants are mainly embedded within the outermost surface layer of the laminates, a light removal of epoxy matrix from the adjoining interfaces has a beneficial effect on adhesion and bond reliability [ 10 , 11 , 12 ]. The most common surface preparation methods for CFRP include the use of peel-plies, corona discharge, flame, plasma, or laser treatments [ 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Peel-plies are simple to apply and provide (reproducible) surfaces that are often unsuitable for adhesive bonding, unless used in combination with another surface treatment [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

“…Oxygen plasma can increase carbonyl content and etch the surface, increasing roughness, wettability, and the strength of adhesive joints [ 14 ]. Pulsed lasers at various wavelengths, including ultraviolet [ 15 ], near-infrared [ 16 ], and infrared [ 17 , 18 ], are also very effective and can remove embedded contaminants through photochemical or photothermal interactions, with consequent improvement of wetting and surface energy.…”

Section: Introductionmentioning

confidence: 99%

“…However, CFRP laminates are often provided with a small surface matrix layer and are quite sensitive to mechanical abrasion. Thus, it can be challenging to prevent significant exposure of carbon fibers; see for instance [ 15 , 17 , 18 ], to list a few. However, as shown in this paper, having a surface that does not feature a high percentage of the polymer matrix does not necessarily represent a weakness for a composite-bonded joint.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Mechanical Pretreatments on Damage Mechanisms and Fracture Toughness in CFRP/Epoxy Joints

et al. 2021

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Adhesive bonding of carbon-fiber-reinforced polymers (CFRPs) is a key enabling technology for the assembly of lightweight structures. Surface pretreatment is necessary to remove contaminants related to material manufacturing and ensure bond reliability. The present experimental study focuses on the effect of mechanical abrasion on the damage mechanisms and fracture toughness of CFRP/epoxy joints. The analyzed CFRP plates were provided with a thin layer of surface epoxy matrix and featured enhanced sensitivity to surface preparation. Various degrees of morphological modification and fairly controllable carbon fiber exposure were obtained using sanding with emery paper and grit-blasting with glass particles. In the sanding process, different grit sizes of SiC paper were used, while the grit blasting treatment was carried by varying the sample-to-gun distance and the number of passes. Detailed surveys of surface topography and wettability were carried out using various methods, including scanning electron microscopy (SEM), contact profilometry, and wettability measurements. Mechanical tests were performed using double cantilever beam (DCB) adhesive joints. Two surface conditions were selected for the experiments: sanded interfaces mostly made of a polymer matrix and grit-blasted interfaces featuring a significant degree of exposed carbon fibers. Despite the different topographies, the selected surfaces displayed similar wettability. Besides, the adhesive joints with sanded interfaces had a smooth fracture response (steady-state crack growth). In contrast, the exposed fibers at grit-blasted interfaces enabled large-scale bridging and a significant R-curve behavior. While it is often predicated that quality composite joints require surfaces with a high percentage of the polymer matrix, our mechanical tests show that the exposure of carbon fibers can facilitate a remarkable toughening effect. These results open up for additional interesting prospects for future works concerning toughening of composite joints in automotive and aerospace applications.

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“…They investigated the technical feasibility of using a low power continuous wave carbon dioxide laser for removing the top resin layer of CFRP without damaging the underlying fibers. Tao et al investigated the effects of carbon dioxide laser irradiation surface pretreatments on the mode I fracture toughness of adhesively bonded CFRP composite joints . In that report, a light surface cleaning with minor changes of surface roughness was performed by low pulse fluence, and also higher pulse fluence was deployed to fully expose carbon fibers.…”

Section: Introductionmentioning

confidence: 99%

Laser surface treatment of CFRP composites for a better adhesive bonding owing to the mechanical interlocking mechanism

et al. 2019

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Adhesion can be greatly improved by the correct surface preparation techniques. One of the most common and useful technique is specific surface structuring which leads to mechanical interlocking and greater adhesion. This work describes the effect of laser-induced line pattern surface structuring on the mechanical interlocking mechanism and so on the adhesive bonding of carbon fiber reinforced polymer (CFRP) composites. Surface patterns with different laser scribes were obtained by CO 2 laser treatment. The effect of the number of a laser shot, the scribe depth, the number of the scribe and the angle between the direction of the laser scribes and mechanical test direction on the adhesive bonding strength of CFRP/CFRP joints was investigated by performing the single lap shear tests according to the ASTM D5868-01. After destructive tests, damaged surfaces were analyzed for determining the failure mechanisms. Mechanical tests showed that laser scribe characteristics especially the number of laser shot and the number of scribes have significant effects on the mechanical interlocking mechanism and so on the adhesion bonding strength. It is suggested that in order to improve the adhesion strength of CFRP/CFRP joints, mechanical interlocking mechanism shall be obtained by optimized laser scribe patterns. POLYM. COMPOS., 40:3611-3622, 2019.

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Laser-based surface patterning of composite plates for improved secondary adhesive bonding

Cited by 74 publications

References 30 publications

A New Design for Friction Stir Spot Joining of Al Alloys and Carbon Fiber-Reinforced Composites

A New Design for Friction Stir Spot Joining of Al Alloys and Carbon Fiber-Reinforced Composites

Effect of Mechanical Pretreatments on Damage Mechanisms and Fracture Toughness in CFRP/Epoxy Joints

Laser surface treatment of CFRP composites for a better adhesive bonding owing to the mechanical interlocking mechanism

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