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Special Issue "Fusion Bonding/Welding of Polymer Composites"

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Advanced Composites".

Deadline for manuscript submissions: 10 August 2022 | Viewed by 3105

Special Issue Editors

Prof. Dr. Patricia Krawczak
E-Mail Website
Guest Editor
Centre for Materials and Processes, IMT Lille-Douai, Institut Mines-Télécom, Douai, France
Interests: advanced composites; polymer composites; composites manufacturing and properties; polymer processing and properties; advanced manufacturing; additive manufacturing and 3D printing; structural health monitoring; recycling; bio-based polymers and composites
Special Issues, Collections and Topics in MDPI journals
Dr. André Chateau Akué Asséko
E-Mail Website
Guest Editor
Centre for Materials and Processes, IMT Lille-Douai, Institut Mines-Télécom, Douai, France
Interests: physics of materials (thermal, optical, mechanical and acoustic); coupling numerical (modeling/simulation) and experimental (validation/identification) aspects for the analysis of the behavior of polymers and composites, their forming and their assembly by different processes (laser or infrared welding, 3D printing/additive manufacturing)
Prof. Dr. Chung-Hae Park
E-Mail Website
Guest Editor
Centre for Materials and Processes, IMT Lille-Douai, Institut Mines-Télécom, Douai, France
Interests: advanced composites; polymer composites; composites manufacturing and properties; advanced manufacturing; numerical simulation and modeling

Special Issue Information

Dear Colleagues,

Most everyday products and industrial structures are made by the assembly of several parts and therefore contain joints. This is the case for example in the aeronautics, railway, or automotive industries where polymer composites become more and more popular as lightweight substitutes of metallic materials. Joining of polymer composites may be achieved by different technologies, as in the case of metals. However, one of the greatest drivers for thermoplastic composites use is the ability to join components via fusion bonding/welding, which is an attractive alternative to conventional methods—mechanical fastening and adhesive bonding—used to join thermoset composite parts.
Although some methods such as resistance welding or induction welding are quite well established, other technologies, including ultrasonic welding, laser welding, infrared welding or conduction welding, are still at a more or less advanced development stage. One of the challenges is to master the interfacial phenomena, structure and quality in the assembly area (welds), which is rather tricky due to the presence of the reinforcement fibers. The same issues are also to tackle for 3D-printed or overmolded parts. Besides, there is a need for reliable predictive process simulation softwares, and also for increased inline monitoring and control of welding process parameters.

This Special Issue welcomes papers (original research articles, state-of-the art reviews, short communications, perspectives, viewpoints, opinions, concept papers or case reports) on the latest advances and development of fusion bonding/welding of thermoplastic composites (i.e., fiber reinforced thermoplastics). Suggested contributions may address materials, processing, modeling/simulation, monitoring/control, performance or application issues, with either experimental or numerical approches.

Prof. Dr. Patricia Krawczak
Dr. André Chateau Akué Asséko
Prof. Dr. Chung-Hae Park
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Materials is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2300 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • welding technology
  • assembly
  • joining
  • fusion bonding
  • resistance welding
  • induction welding
  • ultrasonic welding
  • laser welding
  • infrared welding
  • conduction welding
  • infrared welding
  • microwave welding
  • extrusion welding
  • additive manufacturing
  • 3D printing
  • overmolding
  • inline process control
  • in situ process monitoring
  • process modeling and simulation
  • welds properties
  • polymer composites
  • advanced composites
  • thermoplastic composites

Published Papers (5 papers)

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Research

Article
Facile Surface Depolymerization Promotes the Welding of Hard Epoxy Vitrimer
Materials 2022, 15(13), 4488; https://doi.org/10.3390/ma15134488 - 25 Jun 2022
Viewed by 173
Abstract
Welding via bond exchange reactions has provided advances in obtaining high-quality joining performance. However, the reported welding method requires a relatively high press force, and challenges are still encountered in welding hard vitrimer. In this work, a facile surface depolymerization strategy was introduced [...] Read more.
Welding via bond exchange reactions has provided advances in obtaining high-quality joining performance. However, the reported welding method requires a relatively high press force, and challenges are still encountered in welding hard vitrimer. In this work, a facile surface depolymerization strategy was introduced to weld high-performance epoxy vitrimer. The vitrimers were firstly dissolved into ethylene glycol for depolymerization based on the solvent-assisted bond exchange reactions. Then, the depolymerized vitrimers were welded under heat and press force. The effect of the depolymerizing time, welding pressure, welding temperature and welding time on the welding strength were further investigated. It was found that there were optimal values for the depolymerizing time, welding pressure, and welding temperature, respectively, for the welding strength, while the welding strength increased with increasing welding time. Through facile surface degradation, the welding pressure was highly reduced, while the welding strength was increased. With surface depolymerization, the welding strength was 1.55-times higher, but the magnitude of press force was 1/1000-times than that with no surface depolymerization. It is elucidative that surface depolymerization can be used to weld hard vitrimer composites alongside reducing the press force effectively. Full article
(This article belongs to the Special Issue Fusion Bonding/Welding of Polymer Composites)
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Article
The Mechanical Characterization of Welded Hybrid Joints Based on a Fast-Curing Epoxy Composite with an Integrated Phenoxy Coupling Layer
Materials 2022, 15(3), 1264; https://doi.org/10.3390/ma15031264 - 08 Feb 2022
Viewed by 475
Abstract
The joining of composites mostly relies on traditional joining technologies, such as film or paste adhesives, or mechanical fasteners. This study focuses on the appealing approach of using standard thermoplastic welding processes to join thermosets. To achieve this, a thermoplastic coupling layer is [...] Read more.
The joining of composites mostly relies on traditional joining technologies, such as film or paste adhesives, or mechanical fasteners. This study focuses on the appealing approach of using standard thermoplastic welding processes to join thermosets. To achieve this, a thermoplastic coupling layer is created by curing with a thermoset composite part. This leads to a functional surface that can be utilized with thermoplastic welding methods. The thermoplastic coupling layer is integrated as a thin film, compatible with the thermoset resin in the sense that it can partially diffuse in a controlled way into the thermoset resin during the curing cycle. Recent studies showed the high affinity for the interphase formation of poly hydroxy ether (phenoxy) film as coupling layer, in combination with a fast-curing epoxy system that cures within 1 min at 140 °C. In this study, an investigation based on resistance and ultrasonic welding techniques with different testing conditions of single-lap shear samples (at room temperature, 60 °C, and 80 °C) was performed. The results showed strong mechanical strengths of 28.9 MPa (±0.7%) for resistance welding and 24.5 MPa (±0.1%) for ultrasonic welding, with only a minor reduction in mechanical properties up to the glass transition temperature of phenoxy (90 °C). The combination of a fast-curing composite material with an ultra-fast ultrasonic joining technology clearly demonstrates the high potential of this joining technique for industrial applications, such as automotive, sporting goods, or wind energy. The innovation allowing structural joining performance presents key advantages versus traditional methods: the thermoplastic film positioning in the mold can be automated and localized, joint formation requires only a fraction of a second, and the joining operation does not require surface preparation/cleaning or structure deterioration (drilling). Full article
(This article belongs to the Special Issue Fusion Bonding/Welding of Polymer Composites)
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Article
Radiative Thermal Effects in Large Scale Additive Manufacturing of Polymers: Numerical and Experimental Investigations
Materials 2022, 15(3), 1052; https://doi.org/10.3390/ma15031052 - 29 Jan 2022
Viewed by 494
Abstract
The present paper addresses experimental and numerical investigations of a Large Scale Additive Manufacturing (LSAM) process using polymers. By producing large components without geometrical constraints quickly and economically, LSAM processes have the capability to revolutionize many industries. Accurate prediction and control of the [...] Read more.
The present paper addresses experimental and numerical investigations of a Large Scale Additive Manufacturing (LSAM) process using polymers. By producing large components without geometrical constraints quickly and economically, LSAM processes have the capability to revolutionize many industries. Accurate prediction and control of the thermal history is key for a successful manufacturing process and for achieving high quality and good mechanical properties of the manufactured part. During the LSAM process, the heat emitted by the nozzle leads to an increase in the temperature of the previously deposited layer, which prepares the surface for better adhesion of the new layer. It is therefore necessary to take into account this part of heat source in the transient heat transfer equation to correctly and completely describe the process and predict the temperature field of the manufactured part. The present study contributes to experimental investigations and numerical analysis during the LSAM process. During the process, two types of measurements are performed: firstly, the heat emitted by the nozzle is measured via a radiative heat sensor; secondly, the temperature field is measured using an infrared camera while varying the process speed. At the same time, a numerical simulation model is developed in order to validate the experimental results. The temperature fields of the manufactured parts computed by numerical simulations are in very good agreement with the temperature fields measured by infrared thermograph with the contribution of the nozzle’s heat exchange. Full article
(This article belongs to the Special Issue Fusion Bonding/Welding of Polymer Composites)
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Article
A Study on Through-the-Thickness Heating in Continuous Ultrasonic Welding of Thermoplastic Composites
Materials 2021, 14(21), 6620; https://doi.org/10.3390/ma14216620 - 03 Nov 2021
Cited by 1 | Viewed by 615
Abstract
Continuous ultrasonic welding is a promising technique for joining thermoplastic composites structures together. The aim of this study was to gain further insight into what causes higher through-the-thickness heating in continuous ultrasonic welding of thermoplastic composites as compared to the static process. Thermocouples [...] Read more.
Continuous ultrasonic welding is a promising technique for joining thermoplastic composites structures together. The aim of this study was to gain further insight into what causes higher through-the-thickness heating in continuous ultrasonic welding of thermoplastic composites as compared to the static process. Thermocouples were used to measure temperature evolutions at the welding interface and within the adherends. To understand the mechanisms causing the observed temperature behaviours, the results were compared to temperature measurements from an equivalent static welding process and to the predictions from a simplified heat transfer model. Despite the significantly higher temperatures measured at the welding interface for the continuous process, viscoelastic bulk heat generation and not thermal conduction from the interface was identified as the main cause of higher through-the-thickness heating in the top adherend. Interestingly the top adherend seemed to absorb most of the vibrational energy in the continuous process as opposed to a more balanced energy share between the top and bottom adherend in the static process. Finally, the higher temperatures at the welding interface in continuous ultrasonic welding were attributed to pre-heating of the energy director due to the vibrations being transmitted downstream of the sonotrode, to reduced squeeze-flow of energy director due to the larger adherend size, and to heat flux originating downstream as the welding process continues. Full article
(This article belongs to the Special Issue Fusion Bonding/Welding of Polymer Composites)
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Article
Experimental and Numerical Development on Multi-Material Joining Technology for Sandwich-Structured Composite Materials
Materials 2021, 14(20), 6005; https://doi.org/10.3390/ma14206005 - 12 Oct 2021
Cited by 1 | Viewed by 649
Abstract
Creating connection points for sandwich-structured composites without losing technical performance is key to realising optimal lightweight structures. The patented LiteWWeight® technology presents cost-effective connections on sandwich panels in a fraction of a few seconds without predrilling. Ultrasonic equipment is used to insert [...] Read more.
Creating connection points for sandwich-structured composites without losing technical performance is key to realising optimal lightweight structures. The patented LiteWWeight® technology presents cost-effective connections on sandwich panels in a fraction of a few seconds without predrilling. Ultrasonic equipment is used to insert a thermoplastic fastener into the substrate material and partially melt it into the porous internal structure. This creates a highly interlocked connection (connection strength is above 500 N) suitable for semi-structural applications. This study focused on the simulation and experimental validation of this process, mainly on the interaction between the pin and the substrate material during the joining process. The dynamic thermo-mechanical model showed reasonable agreement with experimental methods such as process data, high-speed camera monitoring or computed tomography and allowed the prediction of the connection quality by evaluation of the degree of interlock. The connection strength prediction by the developed model was validated within several various process setups, resulting in a prediction accuracy between 94–99% depending on the setup. Full article
(This article belongs to the Special Issue Fusion Bonding/Welding of Polymer Composites)
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