A Review of Structural Adhesive Joints in Hybrid Joining Processes

Hybrid joining (HJ) is the combination of two or more joining techniques to produce joints with enhanced properties in comparison to those obtained from their parent techniques. Their adoption is widespread (metal to metal joint, composite to composite and composite to metal) and is present in a vast range of applications including all industrial sectors, from automotive to aerospace, including naval, construction, mechanical and utilities. The objective of this literature review is to summarize the existing research on hybrid joining processes incorporating structural adhesives highlighting their field of application and to present the recent development in this field. To achieve this goal, the first part presents an introduction on the main class of adhesives, subdivided by their chemical nature (epoxy, polyurethane, acrylic and cyanoacrylate, anaerobic and high-temperature adhesives) The second part describes the most commonly used Hybrid Joining (HJ) techniques (mechanical fastening and adhesive bonding, welding processes and adhesive bonding) The third part of the review is about the application of adhesives in dependence of performance, advantage and disadvantage in the hybrid joining processes. Finally, conclusions and an outlook on critical challenges, future perspectives and research activities are summarized. It was concluded that the use of hybrid joining technology could be considered as a potential solution in various industries, in order to reduce the mass as well as the manufacturing cost.

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European Adhesive Bonder

U Porto Journal of Engineering ◽

10.24840/2183-6493_007.001_0006 ◽

2021 ◽

Vol 7 (1) ◽

pp. 37-47

Author(s):

Ana Barbosa ◽

Lucas Da Silva ◽

Ana Loureiro ◽

Eduardo Marques ◽

Ricardo Carbas ◽

...

Keyword(s):

European Union ◽

Adhesive Bonding ◽

Industrial Applications ◽

The European Union ◽

Approval Rate ◽

Industrial Sectors ◽

Wide Range ◽

Mechanical Fastening ◽

Level Of Training ◽

The University

Adhesive bonding is increasingly being used in industrial applications mainly due to its adaptability and ability to reliably join a wide range of materials. Numerous industrial sectors have now adopted adhesive bonding as a key manufacturing technology, with the automotive industry being the leader in adhesive usage. This is a key sector for the European Union (climate and energy policy, which has established a target of improving energy efficiency in the European Union by 20% by 2020. Consequently, this industry is constantly demanding lighter, stronger, more durable and more environmentally friendly materials. The increasing popularity of this technology is linked to the noteworthy benefits related with its application, compared to traditional joining process, such as welding or mechanical fastening process. With the increasing popularity of such joining techniques comes the necessity to train qualified professionals. The European Welding Federation developed a harmonized qualification system, which divides the training process into 3 levels: European Adhesive Bonder (EAB), Specialist (EAS) and Engineer (EAE). Currently, in Portugal, the first level of training, corresponding to European Adhesive Bonder is already in operation. The EAB level is accredited by the European Welding Federation (EWF) and therefore meets the requirements of EWF-515r1-10 and EWF-515r2-19 to which the Faculty of Engineering of the University of Porto is bound as a result of the accreditation as an ATB (Authorized Training Body). This training is targeted for professionals using adhesive bonding technology and professionals who do not currently use this technology but want to use it, and as such has a strong practical component. In Portugal, since 2016, three EWF certified editions have been held, with a high approval rate and met the expectations and objectives of the participants.

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Adhesively bonded joints in components manufactured via selective laser melting

Proceedings of the Institution of Mechanical Engineers Part C Journal of Mechanical Engineering Science ◽

10.1177/0954406220959376 ◽

2020 ◽

pp. 095440622095937

Author(s):

C Koch ◽

J Richter ◽

M Vollmer ◽

M Kahlmeyer ◽

T Niendorf ◽

...

Keyword(s):

Selective Laser Melting ◽

Laser Power ◽

Adhesive Bonding ◽

Melting Process ◽

Mechanical Tests ◽

Laser Melting ◽

Industrial Sectors ◽

Lap Shear ◽

Research Activities ◽

Powder Recycling

Additive manufacturing has gained increasing attention in recent years in numerous industrial sectors due to its inherent characteristics, e.g. tool-free production and unprecedented freedom of design. However, in some applications such as heat exchangers the design has to follow certain restrictions, e.g. to allow for the removal of unfused powder, which can be enclosed in cavities. Moreover, in case multi-material parts are considered, the use of different powders during processing is often uneconomical since powder recycling is highly challenging. Therefore, the production of complex structures being characterized by limited accessibility and components made of different materials often require a subsequent joining process. Based on an analysis of state-of-the-art joining technologies employed for additively manufactured metal components, research gaps related to adhesive bonding are deduced. In light of the prevailing gaps, the influence of selective laser melting process parameters like laser power and build direction on the surface topography and, thus, on the bondability of the substrates are investigated. The mechanical tests reveal a high bond strength for the vertically oriented samples and the samples manufactured with a laser power of 400 W. Furthermore, a laser post-treatment of the SLM samples lead to an improvement of lap shear strength. Finally, results reporting on the ageing behaviour of these joints and an outlook on further research activities are given.

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Joining by forming of metal–polymer sandwich composite panels

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1177/0954405418815386 ◽

2018 ◽

Vol 233 (10) ◽

pp. 2089-2098 ◽

Cited By ~ 2

Author(s):

João PM Pragana ◽

Tomás RM Contreiras ◽

Ivo MF Bragança ◽

Carlos MA Silva ◽

Luis M Alves ◽

...

Keyword(s):

Adhesive Bonding ◽

Sandwich Composite ◽

Composite Panels ◽

Forming Process ◽

Joining By Forming ◽

Bulk Forming ◽

New Concepts ◽

Mechanical Fastening ◽

Mortise And Tenon ◽

Metal Polymer

This article presents new joining-by-forming processes to assemble longitudinally two metal–polymer sandwich composite panels perpendicular to one another. Process design draws from an earlier development of the authors for metal sheets to new concepts based on the combination of sheet-bulk forming with mortise-and-tenon joints. Selected examples obtained from experimentation and finite element modelling give support to the presentation. A new three-stage joining by the forming process is capable of producing mechanically locked joints with larger and stiffer flat-shaped heads than those fabricated by alternative single- or two-stage solutions. Failure in the new three-stage joining by the forming process is found to take place by cracking instead of disassembling after unbending the flat-shaped head of the joint back to its original shape. The required forming forces to produce the new metal–polymer joints are below 15 kN, allowing them to be an effective, easy-to-implement alternative to existing solutions based on adhesive bonding, welding and mechanical fastening.

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How surfaces of carbon fiber reinforced plastics with thermoset matrices need to be treated for structural adhesive bonding

The Journal of Adhesion ◽

10.1080/00218464.2018.1519702 ◽

2018 ◽

Vol 96 (9) ◽

pp. 839-854 ◽

Cited By ~ 4

Author(s):

Jens Holtmannspötter

Keyword(s):

Carbon Fiber ◽

Adhesive Bonding ◽

Fiber Reinforced ◽

Carbon Fiber Reinforced Plastics ◽

Reinforced Plastics ◽

Fiber Reinforced Plastics ◽

Carbon Fiber Reinforced ◽

Structural Adhesive

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Introduction

10.31399/asm.tb.ps.t62440001 ◽

2004 ◽

pp. 1-47

Keyword(s):

Surface Tension ◽

Adhesive Bonding ◽

Solid Materials ◽

Principal Characteristics ◽

Parent Materials ◽

Intermetallic Growth ◽

Joint Gap ◽

Mechanical Fastening ◽

And Diffusion ◽

Solid State Joining

Abstract Soldering and brazing represent one of several types of methods for joining solid materials. These methods may be classified as mechanical fastening, adhesive bonding, soldering and brazing, welding, and solid-state joining. This chapter summarizes the principal characteristics of these joining methods. It presents a comparison between solders and brazes. Further details on pressure welding and diffusion bonding are also provided. The chapter briefly reviews the concepts of surface energy and surface tension, wetting and contact angle, fluid flow, filler spreading characteristics, surface roughness of components, dissolution of parent materials and intermetallic growth, significance of the joint gap, and the strength of metals. It examines the principal aspects related to the design and application of soldering processes.

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Structural adhesive bonding characterization using guided Lamb waves and the vertical modes

International Journal of Adhesion and Adhesives ◽

10.1016/j.ijadhadh.2019.102467 ◽

2020 ◽

Vol 98 ◽

pp. 102467 ◽

Cited By ~ 2

Author(s):

Camille Gauthier ◽

Mounsif Ech-Cherif El-Kettani ◽

Jocelyne Galy ◽

Mihai Predoi ◽

Damien Leduc

Keyword(s):

Adhesive Bonding ◽

Lamb Waves ◽

Structural Adhesive

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Wet Welding as a “Serious” Repair Procedure?

Journal of Offshore Mechanics and Arctic Engineering ◽

10.1115/1.2829540 ◽

1998 ◽

Vol 120 (3) ◽

pp. 191-196 ◽

Cited By ~ 4

Author(s):

P. Szelagowski

Keyword(s):

Welding Process ◽

High Hardness ◽

Field Application ◽

Oil Field ◽

Quality Data ◽

Design Criteria ◽

High Porosity ◽

High Hydrogen ◽

Research Activities ◽

Welding Processes

Due to intensive and concentrated research activities during the last 10 to 15 yr, the quality of wet-welded joints has been improved to an extent that this process is currently regarded as a potential alternative to the more costly dry hyperbaric welding processes in comparable water depths. The wet welding process has matured to an interesting alternative repair process due to its high flexibility and versatility and its low investment costs with respect to achieving comparable weldment quality. However, due to the previous bad reputation of the poor weldment quality in former times, related to extremely high hardness, high porosity, high hydrogen contamination, and, in combination with this, high cracking susceptibility, the wet welding process still requires concentrated activities to improve its reputation and credibility, especially in European oil field application. New acceptance creiteria, more detailed information on the achievable weldment quality, and especially the development of life-predicting data for wet-welded components on the one hand, and new design criteria especially related to the process application in wet environment as well as excellent training of diver welders on the other hand, have been required. Advanced testing methods had to be applied, additional design criteria had to be developed, and achievable weldment quality data had to be included in acknowledged and approved standards and recommendations in training and certification standards for diver welders. All these data are now available. These results have been achieved with the financial support of the European Community through the THERMIE PROJECT FUNDING.

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