Off-Axis and On-Axis Performance of Novel Acrylic Thermoplastic (Elium®) 3D Fibre-Reinforced Composites under Flexure Load

The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that the on-axis specimens show linear response and brittle failure; in contrast, the off-axis specimens depicted highly The flexure response of novel thermoplastic (Elium®) 3D fibre-reinforced composites (FRC) was evaluated and compared with a conventional thermoset (Epolam®)-based 3D-FRC. Ten different types of sample 3D-FRC were prepared by varying fibre orientations, i.e., 0°, 30°, 45°, 60° and 90°, and resin system, i.e., thermoplastic and thermoset. The bending characteristics and failure mechanisms were determined by conducting a three-point bend test. Results elucidate that the on-axis specimens show linear response and brittle failure; in contrast, the off-axis specimens depicted highly nonlinear response and ductile failure. The thermoplastic on-axis specimen exhibited almost similar flexure strength; in comparison, the off-axis specimens show ~17% lower flexure strength compared to thermoset 3D-FRC. Thermoplastic 3D-FRC shows ~40% higher energy absorption, ~23% lower flexure modulus and ~27% higher flexure strains as compared to its thermoset counterpart

Off-axis tensile performance of notched resin-infused thermoplastic 3D fibre-reinforced composites

This study presents a comparison of off-axis tensile performance for notched (open-hole) and unnotched (no-hole) 3D fibre reinforced composites (FRC) specimens having two different types of matrices. The two matrix systems compared are, a novel infusible thermoplastic (Elium) resin and conventional thermoset (epoxy). Three different configurations, (one unnotched and two notched) were tested for each 3D-FRC. The resulting notched net strength, gross strength, failure strains, notch sensitivity and energy absorbed by each configuration were evaluated and compared. Additionally, 2D digital image correlation (DIC) was used to evaluate full-field strain distribution in each case. The results elucidate that thermoplastic 3D-FRCs are notch insensitive irrespective of the notch size and possess higher failure strains (around 30 percent in the cases investigated) and energy absorption (around 33 percent in the cases investigated). In contrast, thermoset 3D-FRC appeared to be notch sensitive, as the notched size increased, and they failed at lower axial strains (up to 60 percent reduction compared to unnotched specimens for the size investigated). Thus, resin-infused thermoplastic off-axis configurations are effective for composite joint applications, particularly in notch-insensitive designs, requiring higher energy absorption and failure strains

Multiscale Damage Modelling of Notched and Un-Notched 3D Woven Composites With Randomly Distributed Manufacturing Defects

This work proposes a stochastic multiscale computational framework for damage modelling in 3D woven composite laminates, by considering the random distribution of manufacturing-induced imperfections. The proposed method is demonstrated to be accurate, while being simple to implement and requiring modest computational resources. In this approach, a limited number of cross-sectional views obtained from micro-computed tomography (µCT) are used to obtain the stochastic distribution of two key manufacturing-induced defects, namely waviness and voids. This distribution is fed into a multiscale progressive damage model to predict the damage response of three-dimensional (3D) orthogonal woven composites. The accuracy of the proposed model was demonstrated by performing a series of finite element simulations of the un-notched and notched tensile tests (having two different hole sizes) for resin-infused thermoplastic (Elium®) 3D woven composites. Excellent correlation was achieved between experiments and the stochastic finite element simulations. This demonstrates the effectiveness of the proposed stochastic multiscale model. The model successfully captured the stochastic nature of tensile responses (ultimate tensile strength and stiffness), damage modes (matrix damage and fibre failure), and initiation and propagation of transverse cracks in thermoplastic 3D woven composites, consistent with experimental observation. The stochastic computational framework presented in this paper can be used to guide the design and optimization of 3D textile composite structures

Multiscale damage modelling of 3D woven composites under static and impact loads

A multiscale progressive damage modelling methodology for 3-dimensional (3D) woven composites is presented. The proposed methodology is generic and can be implemented in most finite element software to create a digital twin for simulation of damage response. It uses 3D solid element (reduced integration) representation of the part for global analysis, while the local damage response, as well as matrix nonlinearity is modelled using a mesoscale constitutive unit-cell model of 3D woven composite consisting of idealised regions of polymer matrix and impregnated yarns. The idealised unit-cell model is defined based on realistic input from X-ray tomography of the 3D woven composite part and the micro-level constituent properties of the matrix and fibres. The damage model has been validated using quasi-static tensile/compression tests as well as dynamic drop-weight impact tests for both thermoset (epoxy) and thermoplastic (Elium) 3D woven composites. These simulations successfully demonstrate the accuracy and efficiency of the model for both 3D-textile composites.The authors would like to acknowledge the financial support provided by Universiti Teknologi PETRONAS (grant number 015LC0-197). The authors would also like to acknowledge the support of Dr. Pierre Gerard from Arkema and Dr. Sharp Keith from TexTech industries in acquiring Elium® resin and 3D fabric for this research work, Dr. Faiz Ahmad and Advance Functional Material (AFM) lab Universiti Teknologi PETRONAS in providing the facility for the fabrication of 3D woven composites

Compression and buckling after impact response of resin-infused thermoplastic and thermoset 3D woven composites

Damage tolerance of a unique resin-infused thermoplastic (Elium) 3D fibre-reinforced composite (3D-FRC) is compared with the conventional resin-infused thermoset (Epoxy) 3D-FRC using compression after impact (CAI) tests and finite element simulations. Higher damage tolerance is demonstrated for the thermoplastic 3D-FRC as its CAI failure strength and CAI stiffness is nearly insensitive to the impact energy levels and subsequent damage, while in contrast, both these properties for the thermoset 3D-FRC get compromised significantly. The buckling performance shows a gradual, almost linear, reduction in critical buckling (44.5% reduction in 0–100 J) for the thermoplastic 3D-FRC. In comparison, the thermoset 3D-FRC shows a much steeper drop in critical buckling, which becomes more pronounced for the higher impact energy cases (84.5% reduction in 0–100 J). It is postulated that the local plastic deformation of the thermoplastic matrix at the impact site as well as better interfacial adhesion is responsible for its better damage tolerance.The authors would like to acknowledge the financial support provided by Universiti Teknologi PETRONAS (grant number 015LC0-197). The authors would also like to acknowledge the support of Dr. Robert J. Barsotti from Arkema in acquiring Elium® resin, Dr. Faiz Ahmad and the Center of Advanced Functional Materials (AFM) in providing the facility for the fabrication of 3D composites

Tensile Behaviour and Morphology of Polypropylene/Polycar-bonate/Polypropylene-graft-maleic Anhydride Blends

This work investigates the effect of blending polycarbonate (PC) into polypropylene (PP) matrix polymer on mechanical tensile properties and morphology. The blends, containing 5% to 35% of polycarbonate and 5% compatibilizer, were compounded using twin-screw extruder and fabricated into standard tests samples using injection molding. The compatibilizer used was polypropylene-graft-maleic anhydride (PP-g-MA). The values of tensile strengths and moduli for PP/PC/PP-g-MA blends were lower than that of pure PP. Tensile strength of pure PP was 37.74 MPa, whereas the highest tensile strength among the blends was 32.60 MPa at 70/25/5 composition. The pattern for the blends is non-linear, where the optimum amount of PC for tensile strength was 25%. Addition of PP-g-MA imparts positive effect towards the blends, shown by higher value for both tensile strength and tensile modulus compared to the noncompatibilized blend. Microscopy analysis showed PC reinforcement phase existed as particulates dispersed in PP matrix phase. PC particulates size depends on its fraction and compatibilizer content. As PC content in compatibilized blends increases, its particulate size also increases

Experimental investigation on the quasi-static crush performance of resin-infused thermoplastic 3D fibre-reinforced composites

This paper presents the quasi-static crush performance of newer resin-infused thermoplastic 3D fibre reinforced composites (FRC) under axial load. The main objective is to make an assessment of the energy absorption capability of novel 3D composites for improved energy absorbing applications. Flat specimens of resin-infused thermoplastic (TP) and thermoset (TS) 3D composites with three trigger angles, i.e., 15°, 30° and 45° were tested under quasi-static crush loads. The thermoplastic 3D-FRC at 45° trigger angle demonstrated 31% higher specific energy absorption (SEA), and 17% higher average crushing stress. This improved performance is attributed to higher fragmentation failure mechanisms, which absorbed more energy. These results elucidate that the resin-infused thermoplastic composites are suitable for higher energy absorption and lightweight design for automotive and sports applications.The authors would like to acknowledge the financial support provided by Universiti Teknologi PETRONAS under Yayasan Universiti Teknologi PETRONAS, grant number 015LC0-197

Thermal degradation and pyrolysis analysis of zinc borate reinforced intumescent fire retardant coatings

This work aims at evaluating the potential of nano-sized zinc borate as substitution of boric acid for thermal degradation and gaseous products in expandable graphite based intumescent fire retardant coating IFRC systems. The thermal degradation and pyrolysis of intumescent flame retardant coatings was characterized by bunsen burner fire test, thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDX), X-ray diffraction (XRD), fourier transformed infra-red analysis (FTIR), X-ray photoelectron spectroscopy (XPS) and gaseous emission analysis (Py-GC). Bunsen burner fire test reveals that the partial substitution of zinc borate (6.61 mass%) imparts a substantial improvement in thermal stability and reduces steel substrate temperature to 124 °C. From thermogravimetric analysis results, it was shown that this composition increases char residual mass from 39 to 46.14 mass%. The morphological structures of char residue were investigated by FESEM and it indicates that zinc borate promotes more continuous and compact char layers that hinder the heat diffusion and oxygen transmission effectively. XRD and FTIR results show that zinc borate develops a zinc-based glassy intumescent shield i.e. zinc bis (hydroxyanthrapyrimidine) dehydrate (C30H14N4O4Zn·2H2O) that strengthens the char. The new chemical species enhances the thermal stability of the freshly formed char at high temperature and provides an enhanced fire protection. XPS analysis shows the higher carbon contents in formulation IF-5 (6.6 mass%) and endorses high char residue. The Py-GC analysis confirms release of less toxic gaseous products in IF-5 formulation, considering their type and concentration, as compared to control formulation, and is considered as an environmentally safe intumescent formulation

Performance comparison of resin-infused thermoplastic and thermoset 3D fabric composites under impact loading

In this paper, the impact performance of a novel resin-infused acrylic thermoplastic matrix-based 3D glass fabric composite (3D-FRC) has been evaluated and compared with thermoset based 3D-FRC under single as well as recurring strike low velocity impact (LVI) events. The single impact tests revealed that the thermoplastic-based 3D-FRC exhibits up to 45% reduced damage area and can have up to 20% higher impact load-bearing capacity (peak force). The damage mode characterization showed that damage transition energy required for micro to macro damage transition is 27% higher, and back face damage extension is up to 3 times less for thermoplastic-based 3D-FRC. Meanwhile, the recurring strike impact test highlights that the thermoplastic-based 3D-FRC experiences a 50% less damaged area, better structural integrity, and survived more strikes. The comparison of single and repeated LVI tests have also allowed us to present a design criterion for estimating the safe number of repeated LVI events for a given impact energy. The superior impact resistance of thermoplastic-based 3D-FRC is attributed to their higher interlaminar fracture toughness, a tougher fiber-matrix interface, matrix ductility, and unique failure mechanism of yarn straining, which is not present in thermoset composites.The authors would like to acknowledge the financial support provided by Universiti Teknologi PETRONAS (grant number 015LC0-197). The authors would also like to acknowledge the support of Dr. Mohamed Thariq Bin Hameed Sultan from Universiti Putra Malaysia in providing the facility to conduct impact tests at their facility. The authors are grateful to Barsotti Robert from Arkema in providing Elium resin for this research work