Abstract One of the major constraints in welding thermoplastic and thermoset composites is thermal degradation of the thermoset resin under the high temperatures required to achieve fusion bonding of the thermoplastic resin. This paper presents a procedure to successfully prevent thermal degradation of the thermoset resin during high-temperature welding of thermoplastic to thermoset composites. The procedure is based on reducing the heating time to fractions of a second during the welding process. In order to achieve such short heating times, which are much too short for commercial welding techniques such as resistance or induction welding, ultrasonic welding is used in this work. A particularly challenging scenario is analysed by considering welding of carbon-fibre reinforced poly-ether-ether-ketone, with a melting temperature of 340 °C, to carbon-fibre reinforced epoxy with a glass transition temperature of 157 °C.
#1M. H. Khan(U of W: University of Windsor)H-Index: 1
#2O. A. Gali(U of W: University of Windsor)H-Index: 1
Last. A.R. Riahi(U of W: University of Windsor)H-Index: 13
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An experimental investigation was performed to study the effect of surface roughness and oxidation on the shear strength of single-lap-joints of AA6061, AA7075 aluminum alloys and an AISI 1080 steel alloy bonded with two different epoxy adhesives. An optimum surface roughness that provided the maximum shear strength was obtained for all the alloys at room temperature. The variation of the shear stress due to the different heat treatment temperatures revealed that the oxides developed on the allo...
#2B. Valle Grande(TU Delft: Delft University of Technology)H-Index: 1
Last. Rinze Benedictus(TU Delft: Delft University of Technology)H-Index: 34
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Energy directors, responsible for local heat generation in ultrasonic welding, are neat resin protrusions traditionally moulded on the surfaces to be welded. This study evaluates an alternative energy directing solution for ultrasonic welding of thermoplastic composites based on the usage of a loose flat layer of neat resin at the welding interface, referred to as ‘flat energy director’. Analysis of dissipated power, displacement of the sonotrode, welding energy and time as well as weld strength...
Ultrasonic welding is a very fast joining technique well suited for thermoplastic composites, which does not require the use of foreign materials at the welding interface for either carbon or glass fibre-reinforced substrates. Despite very interesting investigations carried out by several researchers on different aspects of the process, ultrasonic welding of thermoplastic composite parts is not well understood yet. This article presents a deep experimental analysis of the transformations and hea...
Abstract Ultrasonic welding of thermoplastic composites is a very interesting joining technique as a result of good quality joints, very short welding times and the fact that no foreign material, e.g. a metal mesh, is required at the welding interface in any case. This paper describes one further advantage, the ability to relate weld strength to the welding process data, namely dissipated power and displacement of the sonotrode, in ultrasonic welding of thermoplastic composite parts with flat en...
Abstract A model for the mechanics (oscillating deformation), heat transfer including viscoelastic heat generation and friction dissipation, and degree of adhesion (intimate contact and healing) is proposed for the initial transient heating phase. Numerical resolution was performed using a multi-physical finite element code. The predicted dissipated power evolution exhibits a good correlation with previous experimental measurement of delivered power, and shows that the apparatus has a global eff...
#1Ulrike Braun(BAM: Bundesanstalt für Materialforschung und -prüfung)H-Index: 34
#2Kerstin Brademann-Jock(BAM: Bundesanstalt für Materialforschung und -prüfung)H-Index: 2
Last. Wolfgang Stark(BAM: Bundesanstalt für Materialforschung und -prüfung)H-Index: 12
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The curing mechanism of an epoxy film containing dicyandiamide (DICY) and an epoxy formulation based on diglycidyl ether of Bisphenol A (DGEBA) polymer was studied as a function of various temperature programs. The investigation was performed in situ, using a thin film of the epoxy mixture on a silicon wafer substrate in a heatable transmission tool of a FTIR spectrometer. Based on these model-curing experiments, a major curing mechanism was proposed, taking into account the appearance, the decr...
Heating mechanisms of ultrasonic welding for thermoplastics were studied via numerical simulation and experiment. Relationship between dynamic modulus and static relaxation modulus of thermoplastics was theoretically analyzed. Segment time—temperature equivalency equation for different temperature ranges and a method for directly separating viscoelastic heat from strain energy were used in the simulation. Temperature measurement tests with poly(methyl methacrylate) specimens were carried out to ...
Joining of thermoplastic composites is an important step in the manufacturing of aerospace thermoplastic composite structures. Therefore, several joining methods for thermoplastic composite components have been under investigation and development. In general, joining of thermoplastic composites can be categorized into mechanical fastening, adhesive bonding, solvent bonding, co-consolidation, and fusion bonding or welding. Fusion bonding or welding has great potential for the joining, assembly, a...
Abstract An investigation of the resistance welding between carbon fibre (CF)-reinforced polyetherimide (PEI) and CF-reinforced epoxy laminates is presented. A three-dimensional transient finite element model (FEM) featuring heat transfer, consolidation and thermal degradation was used for simulating the process. A hybrid interlayer made of a glass fibre (GF) fabric essentially impregnated with PEI on one side and with epoxy resin on the other side was produced to provide mechanical interlocking...
Last. Meng Hou(CRCs: Cooperative Research Centre)H-Index: 15
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Abstract Joining composite materials is an issue because traditional joining technologies are not directly transferable to composite structures. Fusion bonding and the use of thermoplastic films as hot melt adhesives offer an alternative to mechanical fastening and thermosetting adhesive bonding. Fusion bonding technology which originated from the thermoplastic polymer industry has gain a new interest with the introduction of thermoplastic matrix composites (TPC) which are currently regarded as ...
Fusion assembly is a highly promising technique for joining thermoplastic composite to thermoset composites, enabling the use of both the most affordable composite material and process for each substructure. However, some major challenges need to be addressed such as functionalizing the thermoset composite surface through co-curing with an appropriate thermoplastic interlayer or realizing a fast and robust welding process that meets all quality and mechanical requirements. In this paper, we inve...
Abstract This paper addresses the sensitivity of the ultrasonic welding process for joining dissimilar composites to variations in either the welding force or amplitude of vibrations. For that, carbon fibre (CF)/epoxy specimens were welded to CF/polyetheretherketone (PEEK) specimens, through a polyetheretherimide (PEI) coupling layer co-cured with the CF/epoxy material. It was found that reducing either the welding force or the amplitude of vibrations caused an increase in the heating time and m...
Abstract This study aims at assessing the sensitivity of the ultrasonic welding process for joining epoxy- to thermoplastic-based composites sensitivity to the heating time. For that, carbon fibre (CF)/epoxy adherends with a co-cured PEI coupling layer were ultrasonically welded to CF/polyetheretherketone (PEEK) adherends at different heating times. Process-induced changes in the meso and microstructure of these welds were identified and correlated to the weld strength. Subsequently, a processin...
#1Quentin Voleppe(UCL: Université catholique de Louvain)H-Index: 3
#2Wael Ballout(UCL: Université catholique de Louvain)H-Index: 6
Last. Thomas Pardoen(UCL: Université catholique de Louvain)H-Index: 64
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ABSTRACT The hybrid assembling of thermoplastics with thermosets through controlled interdiffusion is an attractive approach towards integrated structural composite bonding. The fracture toughness of the interphase between the high Tg thermoplastic polyetherimide and the RTM6 epoxy is found to be four times higher than the corresponding RTM6 value under specific curing cycle. The origin of this remarkable cracking resistance is elucidated by analyzing the crack path in relationship with the morp...
Thermoset fiber reinforced composites, widely used in current structural applications, have complex repair procedures and generates significant amounts of scrap due to its recycling difficulties, which does not comply with the most recent environmental restrictions. These disadvantages may be overcome by using a thermoplastic matrix phase, which is very suitable to be joined and repaired by local melting, making the composite material fully recyclable. This work presents a literature review on t...
Abstract Continuous ultrasonic welding is a promising high-speed and energy-efficient joining method for thermoplastic composite structures. Our aim was to identify and understand differences between the static and continuous ultrasonic welding process for thermoplastic composites. In particular, melting of the interface, consumed power and energy density, temperature evolution at the weld interface, and optimum welding conditions for both types of processes were investigated. This was done for ...
Abstract In the current research, the ultrasonic welding feasibility of carbon/epoxy composite with novel carbon/Elium® (thermoplastic) composites is investigated. As thermoset composites are not weldable, it is essentially required to create a thermoplastic coupling layer to necessitate the welding phenomenon. Two different co-curing methods were investigated to provide the coupling layer to the epoxy laminates, one using Elium® particle (ELP) and others using Elium® film (ELF). The weld streng...
Last. Xuhai Xiong(SAU: Shenyang Aerospace University)H-Index: 16
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The surface of stainless steel (SS) mesh was modified by in-situ growing carbon nanotubes (CNTs) from ethanol flame. Then the interfacial bond strength of SSM and polyetherimide (PEI) was improved ...