Design of laser-textured surfaces to enhance the strength of adhesively bonded joints

Moroni, F.; Romoli, Luca; Khan, M.M.A.

doi:10.1016/j.ijadhadh.2018.06.001

Cited by 25 publications

(9 citation statements)

References 22 publications

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“…Compared to other techniques (e.g., lithography, electrochemical machining, template, plasma, etc. ), the laser processing technology has a wider application in producing surface microstructures to improve interfacial bonding strength due to high efficiency, high flexibility, environmental friendliness, etc. − Nevertheless, the formation of mechanical interlocking is always confronted with one intrinsic problem related to the interfacial wetting of the polymer on surface microstructures, , and insufficient wetting would result in interfacial defects and a significant decrease in interfacial bonding strength, which is one critical problem restricting the application of mechanical interlocking that is receiving increasing attention from engineers and researchers . The difficult filling of polymer into laser-produced dimple and groove microstructures are widely reported in recent literature because of a high surface roughness resulting from inappropriate processing parameters. , As a result, the surface microstructures contribute to interfacial bonding strength by the formation of mechanical interlocking, but it is vulnerable to the excessive surface roughness …”

Section: Introductionmentioning

confidence: 99%

Spindle-Shaped Surface Microstructure Inspired by Directional Water Collection Biosystems to Enhance Interfacial Wetting and Bonding Strength

Wan

Min

Carlson

et al. 2021

ACS Appl. Mater. Interfaces

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Unique spindle microstructures with an apex angle of ∼20° bring the ability of directional water collection to various biosystems (i.e., spider silk and cactus stem). This has great potential to solve the insufficient interfacial wetting for mechanical interlocking formation between polymers and substrates. In this study, the bioinspired spindle microstructures were easily fabricated through the deposition of molten materials by a nanosecond laser with an overlap ratio of 21% between laser spots and achieved superior interfacial wetting for commercial epoxy adhesive on aluminum substrates. Detailed analyses show that there are four mechanisms responsible for the superior interfacial wettability of bioinspired spindle microstructures: the Laplace pressure difference, newly formed aluminum oxide, the capillary effect, and no extra pressure from a trapped atmosphere. Consequently, the bioinspired spindle surface microstructures achieve a maximum improvement of ∼16 and ∼39% in interfacial bonding strength before and after water soak exposure compared to the as-received condition. Moreover, the stable interfacial wettability of bioinspired spindle microstructures ensures that the improved joint strength varied little with an increase in surface roughness from ∼1.7 to ∼12.8 μm. However, the interfacial wettability of common dimple microstructures deteriorated with an increase in surface roughness, which is indicated by the decreasing rule in the quadratic polynomial function of the interfacial bonding strength as the surface roughness increases from ∼2.1 to ∼18.2 μm.

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Section: Introductionmentioning

confidence: 99%

Spindle-Shaped Surface Microstructure Inspired by Directional Water Collection Biosystems to Enhance Interfacial Wetting and Bonding Strength

Wan

Min

Carlson

et al. 2021

ACS Appl. Mater. Interfaces

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show abstract

“…This was due to the fact that the distance between adjacent grooves was significantly smaller than their width and to the accumulation of the debris expelled during the treatment of neighbouring grooves. 24 With a small increase in the hatch distance, up to 50 µm, the surface morphology presented small peaks and valleys, although their height was again partially limited by the high overlay between adjacent grooves and by the debris accumulation. For a hatch distance equal to 100 µm, there was no overlap between adjacent grooves, and the surface resulted in a very organized morphology characterized by a high peaks and deep valleys grid.…”

Section: Resultsmentioning

confidence: 98%

Influence of laser ablation-induced surface topology on the mechanical behaviour of aluminium bonded joints

Moroni

Musiari

Pirondi

2018

Proceedings of the Institution of Mechanical Engineers, Part L:

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The state of the surface plays a crucial role in defining the mechanical properties of bonded joints, in particular, the chemical state of the adherend surface and its structural morphology have been proved to be the main elements of the bonding process. The structural morphology of the surface strictly depends from its topological features, like roughness, presence and distribution of grooves, homogeneity, etc. In a previous work, the effect provided by pulsed Yb-laser ablation on the mode I energy release rate of aluminium double cantilever beam joints was evaluated, in order to identify a relation between the combination of laser parameters and the morphological characteristics of the ablated surfaces which can support in identifying the optimal process configuration. The experimental tests showed that the fracture toughness of the double cantilever beam joints grew up as the surface roughness increased until a threshold value, after which the grooves resulted too narrow to allow the adhesive to completely fill them, inducing a higher amount of entrapped air into the grooves and therefore reducing the level of failure propagation energy. In this work, the problem dealing with the influence that the presence of air bubbles has over the mechanical behaviour of bonded joints was considered and the study went deeper into the investigation on the relation between laser-induced surface topology and mechanical response of joints. Different surface textures involving different directions and conditions of treatment were realized and their effect on the mechanical properties of aluminium bonded specimens was evaluated through experimental tests. The characterization of the treated surfaces was carried out by observing them with a 3D optical profiler and with SEM analysis and by measuring some geometrical features of the patterns created as a result of laser ablation.

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“…Moroni et al. 34 have found that laser-treatment parameters greatly contribute to surface roughness, which affects the strength of adhesively bonded lap joints. The shear strength of the Line pattern structure with different depth is shown in Figure 5(c).…”

Section: Resultsmentioning

confidence: 99%

“…Many studies have shown that the transition from adhesive failure to cohesive failure can greatly improve bond strength. 8,34 If there is a small/large amount of fibers torn in the composite and remaining on the metal surface, the failure mode is defined as light fiber tear/fiber tear failure. Finally, due to the insufficient strength of the metal, the failure occurs inside the metal rather than on the bonding surface, which is designated as stock brake failure.…”

Section: Failure Modes Of Lap Jointsmentioning

confidence: 99%

Optimization of microstructural morphology via laser processing to enhance the bond strength of Al-CFRP

Liu

Zhu

Xie

et al. 2020

Journal of Reinforced Plastics and Composites

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Generating surface-functional microstructures is an effective way to enhance the bonding strength of metal and carbon fiber-reinforced polymer (CFRP). In this study, different microstructural morphologies consisting of two different patterns were generated on the aluminum alloy (A7075) surface via laser processing. The experimental results indicated that different microstructural morphologies contribute to the enhancement of the shear strength of lap joints. The maximum shear strength of these joints was almost four times stronger than that of lap joints without the microstructures. In addition, the investigation indicated that the shear strength was not only determined by surface roughness and contact area but also by the arrangement of different microstructures. These results are mainly due to the combination of mechanical interlocking and physical adhesion. Finally, the corresponding mechanical models of Al-CFRP lap joints were proposed according to the bonding mechanisms and fracture behaviors.

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Design of laser-textured surfaces to enhance the strength of adhesively bonded joints

Cited by 25 publications

References 22 publications

Spindle-Shaped Surface Microstructure Inspired by Directional Water Collection Biosystems to Enhance Interfacial Wetting and Bonding Strength

Spindle-Shaped Surface Microstructure Inspired by Directional Water Collection Biosystems to Enhance Interfacial Wetting and Bonding Strength

Influence of laser ablation-induced surface topology on the mechanical behaviour of aluminium bonded joints

Optimization of microstructural morphology via laser processing to enhance the bond strength of Al-CFRP

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