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Current research investigates the effect of the core-shell (C/SH) particles in composites manufactured using novel thermoplastic Elium® resin and carbon fiber reinforcement of different areal weights, 200 gsm and 400 gsm bi-angle non-crimp carbon fabrics (NCCFs). The core-shell particles were activated using the ex-situ methodology which involves the activation of particles before the Resin transfer molding (RTM) injection process. Recommended particle activation parameters are established after carrying out a detailed microscopic study to understand the melting and flattening behavior of these particles. Static indentation and damping attributes are studied to understand the influence of C/SH particles added novel carbon/Elium® composite in improving the out-of plane properties and dynamic mechanical attributes respectively. The interply regions were also toughened with the addition of 1% core-shell particles and the intensity of load drop has reduced by 20% while comparing the thick and thin ply NCCF/Elium® composites. Microscopic examination has shown that the core-shell particles helped to spread the damage evenly throughout the specimen and absorbed more energy during the static-indentation. Loss factor or damping for thick ply Elium® composite and thin ply epoxy composite is increased by 19% and 16.4% with the addition of 5% and 1% C/SH particles respectively. The underlying reasons for improvement offered by C/SH particles in quasi-static impact and dynamic mechanical tests are also deliberated in this paper.

Expanded Polystyrene (EPS) is commonly used as an inner liner for a bicycle helmet due to its outstanding energy absorption characteristic and light-weight property. The current investigation presents a novel technique to manufacture hybrid EPS/honeycomb structure foam using an integrated manufacturing approach to further enhance the energy dissipation properties for improved safety against head injuries. Different foam designs were analysed under curb-stone impact tests and the failure mechanisms are deliberated. Integrated EPS-honeycomb hybrid liners have shown up to 20% higher energy absorption, with the additional energy being absorbed in associated densification of foam and the elastic buckling features of the honeycomb.

Expanded Polystyrene (EPS) is a common material used to manufacture the inner foam liner of a bicycle helmet due to its outstanding energy absorption characteristics and light-weight property. The current research presents a novel corrugated expanded polystyrene (EPS) foam design concept which is used to enhance the impact dissipation of bicycle helmets from the safety standpoint to reduce head injuries and make them lighter. The baseline comparison study under impact for different foam configurations is compared with a conventional EPS foam sample without corrugation. Corrugated foam designs under current investigation are 12.5–20% lighter and provide up to 10% higher energy absorption. The details of the novel manufacturing concept, CPSC 1203 helmet impact tests, high-speed camera study to understand the differences in the failure mechanisms are deliberated in this paper.

The bladder molding process is primarily used in sporting applications but mostly with prepregs. Bladder-Assisted Resin Transfer Molding (B-RTM) presents the tremendous potential to automate and mass produce the complex hollow-composite profiles. Thin-ply, non-crimp fabrics (NCFs) provide excellent mechanical, fracture toughness, and vibration damping properties on top of the weight saving it offers to a final product. However, these fiber architectures are difficult to inject due to the resistance they provide for the polymer flow using the liquid injection process. Therefore, it is mandatory to optimize the process parameters to reduce the time for injection and simultaneously achieve better consolidation. This work presents a first, detailed, experimental case study to successfully inject a low-permeability, thin-ply, complex, thermoplastic tubular structure, and the effect of process parameters, boundary conditions, the associated manufacturing challenges, and proposed solutions are deliberated in this paper.

Current research realize to develop a safer, lighter and higher energy absorbing fully thermoplastic (polypropylene fibres and acrylic Elium resin) and hybrid composite helmets (polypropylene/carbon hybrid and Elium resin) and perform the CPSC 1203 certification tests on different anvils. The failure and energy absorption mechanisms were studied and compared with widely used polycarbonate helmets (PC/EPS) and the composite shells manufactured with epoxy resin. The fully thermoplastic and hybrid composite shells have shown up to 65% of absorbed energy while the polycarbonate shells have absorbed a maximum of 13% of the absorbed energy. The usage of composite shells has lead to minimal energy transfer to the foam which is directly attached to the human head and provided improved safety. The high-speed camera has shown clear deformation of the thermoplastic composite shell owing to the ductile behaviour while the catastrophic failure with significant cracks was observed in the Epoxy-based composite shell. Considering the head injury criteria, the PC/EPS helmet showed the highest fatality rate (6%) when impacted on the flat anvil. The usage of fully thermoplastic and hybrid composite shell reduces the probability of critical and fatal injury by around 40% and 60% respectively when compared to PC/EPS configuration.

Fiber reinforced thermoplastic composites are gaining popularity in many industries due to their short consolidation cycles, among other advantages over thermoset-based composites. Computer aided manufacturing processes, such as filament winding and automated fiber placement, have been used conventionally for thermoset-based composites. The automated processes can be adapted to include in situ consolidation for the fabrication of thermoplastic-based composites. In this paper, a detailed literature review on the factors affecting the in situ consolidation process is presented. The models used to study the various aspects of the in situ consolidation process are discussed. The processing parameters that gave good consolidation results in past studies are compiled and highlighted. The parameters can be used as reference points for future studies to further improve the automated manufacturing processes.

Joining large and complex polymer&ndash, matrix composite structures is becoming increasingly important in industries such as automobiles, aerospace, sports, wind turbines, and others. Ultrasonic welding is an ultra-fast joining process and also provides excellent joint quality as a cost-effective alternative to other joining processes. This research aims at investigating the welding characteristics of novel methyl methacrylate Elium&reg, a liquid thermoplastic resin. Elium&reg, is the first of its kind of thermoplastic resin, which is curable at room temperature and is suitable for mass production processes. The welding characteristics of Elium&reg, composites were investigated by optimizing the welding parameters with specially designed integrated energy directors (ED) and manufactured using the Resin transfer molding process. The results showed a 23% higher lap shear strength for ultrasonically welded composite joints when compared to the adhesively bonded joints. The optimized welding time for the ultrasonic welded joint was found to be 1.5 s whereas it was 10 min for the adhesively bonded joint. Fractographic analysis showed the significant plastic deformation and shear cusps formation on the fractured surface, which are typical characteristics for strong interfacial bonding.

The current research work presents a first attempt to investigate the welding attributes of Elium&reg, thermoplastic resin and the fusion bonding using ultrafast ultrasonic welding technique. The integrated energy director (ED) polymer-matrix composites (PMCs) panel manufacturing was carried out using the Resin Transfer Moulding (RTM) technique and the scheme is deduced to manufacture a bubble-free panel. Integrated ED configurations and flat specimens with Elium&reg, film of different thickness at the interface were investigated for ultrasonic welding optimization. Optimised weld time for integrated ED and flat Elium&reg, panels with film (0.5 mm thick) configuration was found to be 1 s and 5.5 s, respectively. The ED integrated configuration showed the best welding results with a lap shear strength of 18.68 MPa. The morphological assessment has shown significant plastic deformation of Elium&reg, resin and the shear cusps formation, which enhances the welding strength. This research has the potential to open up an excellent and automated way of joining Elium&reg, composite parts in automotive, wind turbines, sports, and many other industrial applications.

Current research investigates the structural damping response of hollow tubular structures with novel acrylic liquid thermoplastic Elium® resin (EL) and thin ply carbon(TPC) and woven carbon(WC) as the reinforcement. The results are compared with the baseline tubes manufactured with conventional epoxy (EP) resin systems. The structural damping results have shown 26.7% higher structural damping for TPC/EL and 27.3% higher damping for WC/EL compared to TPC/EP and WC/EP tubular configuration respectively at all the accelerometer positions during the modal analysis tests. The viscoelastic presence in acrylic Elium® and its amorphous chemical structure as opposed to the cross-linked state in epoxy resin and good fibre matrix interfacial bonding is the major contributing factor towards this increase. Damping results have also shown that the thickness of the tube has a positive effect of the structural damping (1.6 mm as opposed to 1.1 mm) and on the contrary, an increase in the fibre volume fraction (64% as opposed to 41%) has an adverse effect on the damping phenomenon, 10% higher and 85% lower respectively.

Laminated polymer composites are extensively used in various applications ranging from aerospace to automotive, building to marine and offshore, and much more. These composites possess higher mechanical properties in their in-plane directions, but lower interlaminar properties. Especially, low interlaminar fracture toughness (ILFT) makes them susceptible to delamination. In the current research, a novel thermoplastic-based thin-ply composite system is conceptualized and manufactured with an aim to improve the through-the-thickness properties and which can be a competitive solution to traditional epoxy-based composites as well as other class of thermoplastic composites. The detailed experimental investigation on determining the Mode I ILFT properties of these thin ply carbon fibre thermoplastic composites, along with thin ply thermoset composites for benchmarking, is carried out. Quasi-isotropic composite laminates were manufactured using a room temperature cure epoxy, and the novel reactive Methylmethacrylate (MMA) liquid thermoplastic resin. The thin ply/liquid MMA composites have shown 30% and 72% higher Mode I ILFT properties compared to the thick ply/liquid MMA and thin ply/Epoxy composites respectively. Surface morphological studies were conducted to understand and differentiate damage mechanisms in these composites. From the comprehended damage mechanisms, it was deduced that strong fibre-matrix interface, plastic deformation as well as features like ductile drawings in liquid MMA composites make them more resistant to crack propagation.

Fiber-reinforced composites are increasingly used as an outer shell of sporting helmets as an alternative to conventional thermoplastic shells like Acrylonitrile butadiene styrene (ABS), Polyurethane (PU), and polycarbonate (PC) for improved protection. The current research presents a detailed study to manufacture novel woven carbon/Elium® (WEL) thermoplastic composite helmets and investigate the details based on the impact tests following the industrial safety certification criteria (CPSC 1203 helmet certification) tests on the flat, curb-stone, and the hemispherical anvils. The effect of thermoplastic Elium® resin toughened thermoplastic Elium® IM, and Epoxy resin is investigated to understand the benefits offered by the thermoplastic variants in terms of safety, energy absorption, and the impact failure mechanisms. Post-failed Carbon/Elium® thermoplastic composite shells have shown more ductile and less catastrophic damage as opposed to the Carbon/Epoxy composite shell damage. The impact damage mechanisms as observed from the in-situ high-speed camera images have shown more deformation-dominated failure mechanisms for the composite shells manufactured with Elium® and toughened Elium® resin. Carbon/Epoxy composite shells have shown lower energy absorption and the nature of the failure was more catastrophic and more cracks were noticed on the inner side of the foam which is directly attached to the human head. In case of an impact on a flat anvil, the PC shell configuration has shown a critical injury rate of 28.7% and a fatality rate of 6%. With the manufactured Carbon/Elium® composite helmets, the chances of critical and fatal injury rates are reduced to 16.7% and 3% respectively.

Hollow thin composite tubular structures are widely used in many industrial applications and there is a growing need to innovate both the manufacturing process which is suitable for mass production as well as the material aspects to improvise the mechanical properties and the weight. The current research presents a detailed study on manufacturing thin hollow woven carbon fibre (WC)/Elium® (EL) rectangular tubular structures. Bladder resin transfer moulding process optimization study is carried out and the moldability zones were defined. A detailed experimental investigation was carried out to understand the impact and flexure properties of woven carbon (WC) tubular configurations with Elium® (EL) and Epoxy (EP) matrix system. Impact tests were performed at 6 different energies to derive the energy profiling diagrams by studying the penetration and preformation thresholds. WC/EL tubular configuration has shown a maximum 12.5% increase in peak load and 55% increase in absorbed energy as compared to WC/EP composite, respectively. The WC/EL composite tubes have shown similar or better results in terms of bending strength (10% higher) and there was a noticeable increase in deformation owing to the extended plasticity behaviour of acrylic thermoplastic resin compared to WC/EP composites. The rationale and underlying reasons for the differences in the mechanical performance and failure mechanisms for both the tubes tested in impact and flexural are studied with the help of high-speed camera examination and microscopic study and are deliberated in this paper.

Current research investigates the low-velocity impact response of the hollow rectangular tubular structures manufactured using Bladder Resin Transfer Moulding (B-RTM) process with novel thermoplastic Elium® (EL) resin as a matrix system and thin ply carbon fibre as the reinforcement. Manufacturing process parameters are optimised and injection schemes and the moldability zones are defined. Low-velocity impact (LVI) tests has been carried out at 5 different energy levels and the failure mechanisms were deduced using an in-situ high-speed camera and microscopic examination. Thin ply carbon/Elium® (TPC/EL) tubular configuration has shown a maximum increase of 18.3% in peak load compared to Thin ply carbon/Epoxy (TPC/EP) composite. TPC/EL composite has shown significantly higher absorbed energies 70.1%, 109.3% and 170% compared to TPC/EP composites while comparing the results at 12.5 J, 14.5 J and 17.5 J respectively. TPC/EL composite has also shown up to 70% higher major damage energy when impacted at significantly higher impact energies. The details of the failure mechanisms and understanding on the load and energy attributes of tubular composite structures are deliberated in this paper.

Reactive thermoplastic matrices are widely used for polymer composites manufacturing owing to their ease of processing using cost-effective liquid injection processes. The novel methyl methacrylate (MMA) Elium ® resin is a liquid thermoplastic resin, first of its kind which is curable at room temperature. It has attracted wide interest as a competitive solution to epoxy-based composites for structural applications. In this work, the flexural performances of novel non-crimp carbon fabric (NCCF) Elium ® composite laminates are evaluated. The baseline comparison is done with conventionally used composites with epoxy resin. The stress-strain curve, the fracture failure mechanisms and the effect of the annealing stage have been discussed. Nanyang Technological University Authors would like to acknowledge the financial support from the Institute for Sports Research, Nanyang Technological University, Singapore, Arkema, France and CHOMARAT, France.

The current research presents a first attempt to manufacture thermoplastic tubular composites using carbon fibre as reinforcement and an innovative Elium® resin as the matrix material using Bladder Assisted Resin Transfer Moulding (B-RTM) manufacturing process. The manufacturing process parameters required to achieve a fully impregnated thermoplastic composites were established, and the parts have undergone impact, flexure, and vibration damping tests. The mechanical properties and the failure modes are compared with the tubes manufactured with conventional epoxy matrix. During impact testing, thermoplastic tubular composites have shown 16.3% and 18.9% higher peak load and major damage energy respectively compared to carbon/epoxy tubes. They have also shown distinctive failure modes, with acrylic Elium® composites tubes undergoing more ductile and spreaded failure whilst epoxy composites have shown brittle and catastrophic failure. Flexural tests have shown comparable load-carrying capability, higher strain to failure, and less delamination for carbon/Elium® composites compared to carbon/epoxy composites. These are attributed to the presence of microductlilty and other associated matrix deformation features shown during the fractographic analysis of carbon/Elium® composites. Vibration modal analysis tests have shown 21.7% higher structural damping for carbon/Elium® composite measured at different output locations on the tube. The differences in the failure mechanisms and the underlying reasons for the improvement shown by thermoplastic Elium® composite tubes under different mechanical tests are deliberated in this paper.

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 strength of the adherends was qualified by the static lap shear test. The result showed that the adherend welded with the addition of 0.31 mg/mm2 of ELP on the epoxy laminate was found to increase the lap shear strength by 95% as compared to the samples welded without the coupling layer. Also, the failure mode obtained with ELP configuration was found to be partially cohesive as opposed to purely adhesive failure for epoxy laminate without the coupling layer.

Microwave curing has a tremendous potential to be used as an alternative to other thermal curing processes due to its shorter curing time and lower consumption of energy. Current research investigates the damping and dynamic mechanical characteristics of core-shell polymer (C/SH) particle modified glass fibre prepreg (GFRP) manufactured using microwave irradiations. The addition of C/SH particles has shown a significant improvement in damping and dynamic mechanical properties. The optimal areal weight per interface (AWI) for C/SH particles was established as 40 gsm. With this optimal addition, the laminates showed a 21.5% increase in mechanical loss factor, tan δ, and 52.7% in the vibration damping capability as noticed from dynamic mechanical and the forced vibration tests respectively. The underlying reasons for the improvement in properties with the addition of C/SH particles are also deliberated in this paper.

For mass production of structural composites, use of different textile patterns, custom preforming, room temperature cure high performance polymers and simplistic manufacturing approaches are desired. Woven fabrics are widely used for infusion processes owing to their high permeability but their localised mechanical performance is affected due to inherent associated crimps. The current investigation deals with manufacturing low-weight textile carbon non-crimp fabrics (NCFs) composites with a room temperature cure epoxy and a novel liquid Methyl methacrylate (MMA) thermoplastic matrix, Elium®. Vacuum assisted resin infusion (VARI) process is chosen as a cost effective manufacturing technique. Process parameters optimisation is required for thin NCFs due to intrinsic resistance it offers to the polymer flow. Cycles of repetitive manufacturing studies were carried out to optimise the NCF-thermoset (TS) and NCF with novel reactive thermoplastic (TP) resin. It was noticed that the controlled and optimised usage of flow mesh, vacuum level and flow speed during the resin infusion plays a significant part in deciding the final quality of the fabricated composites. The material selections, the challenges met during the manufacturing and the methods to overcome these are deliberated in this paper. An optimal three stage vacuum technique developed to manufacture the TP and TS composites with high fibre volume and lower void content is established and presented. Published version