Interply Hybrid Research Articles

Interply hybridization of hollow glass fiber reinforced vascular composites

AbstractThe use of hybrid reinforcement in polymer composites has been getting attention due to its potential for weight and cost reduction while achieving improved design flexibility for mechanical and thermal properties. In this study, an interply hybridization of epoxy laminates was performed using layers of solid and hollow glass fibers. The structural and thermal performance of the resulting hybrid vascular composites was investigated. All composite parts were manufactured using vacuum‐assisted resin transfer molding (VARTM), following an interply hybridization plan for the stacking sequence of hollow and solid fiber layers. An expected decrease in flexural properties and thermal conductivity was observed for the laminates with completely hollow fibers. On the other hand, hybridization had a positive effect on the laminate properties. It was shown that hybrid vascular composites could be manufactured without a significant reduction in mechanical and thermal performance by a judicious hybridization plan. The optimum hybridization of the laminate achieved a 3.1% increase in the specific flexural strength and a 5.3% decrease in thermal conductivity while containing a vascular network that can be used for active thermal control.Highlights A vascular interply composite structure consisting of hollow and solid fibers was manufactured and characterized for the first time. The I4 composite, vascularized through the middle layers of the laminate, has almost as much flexural strength as solid composite and much more specific flexural strength. The thermal conductivity of the I4 composite is almost as much as that of the solid composite. Functional composites for thermal management and smart applications can be manufactured using hollow fibers without sacrificing flexural strength and thermal conductivity with interply vascularization.

Investigating silicon nanoparticles modified sandwich polymer composites for enhanced mechanical performance

ABSTRACT This study investigates the morphology and mechanical behaviour of a bidirectional interply hybrid sandwich polymer composite panel with the addition of silica nanoparticles (SiNPs). The investigation assesses the enhanced performance of sandwich polymer composite panels, focusing on their ability to withstand compression, Euler’s buckling axial load-bearing capacity, and surface roughness when subjected to low-velocity impact events that are barely perceptible for aircraft, automobile, and wind turbines. The composite panel was constructed using interply bidirectional Kevlar, carbon, and glass fibers, an epoxy matrix, and polyurethane (PUR) foam, with the incorporation of four different weight percentages of silica nanoparticles (0%, 2%, and 4% of SiNPs). The sandwich composite panel was fabricated using the hand lay-up technique, following a novel quasi-static stacking sequence method (01 K/01 C/01 G/PUR/01 G/01 C/01 K). Among these composite panels, the addition of 4 wt.% silicon nanoparticles exhibited the highest strength and axial load-carrying capacity compared to the other sandwich composite panels (0 wt.% and 2 wt.%). The mechanical characterisation results showed maximum compressive strengths of ca. 3 MPa, ca. 5 MPa, ca. 10 MPa, and ca. 8 MPa for the 0 wt.%, 2 wt.%, 4 wt.% and 6 wt.% of silica nanoparticles-added composite panels, respectively.

Assessment of low-velocity impact response of a hybrid carbon-aramid braided composite by algorithmic quantification of volumetric structures

This work investigates the impact response of a hybrid two-dimensional (2D) tubular braided composite through an ex-situ examination of its internal structure. An inter-ply hybrid laminate of biaxial braided carbon and aramid layers was manufactured. The sample underwent split Hopkinson pressure bar (SHPB) impact testing, where the applied energy induced barely visible impact damage (BVID). Volumetric representations of the sample were created before and after impact testing using micro-computed tomography (µCT). Novel algorithms were developed to assess properties of the braided composite sample. First, voids in the sample before and after impact were identified through a series of image processing techniques, after which various void properties were extracted. Each void was then matched between datasets to track property change caused by impact. Next, damage in the sample after impact was identified through another series of image processing techniques, then quantified and characterized in the context of the full sample. Statistical analyses in the form of paired-sample t-tests were performed for void properties and overall surface topologies. Additionally, measurement of 3D strain within selected regions of the sample was performed using digital volume correlation (DVC). Results showed that the impact damage did not cause significant void enlargement, but instead caused surface topology shifts, particularly at the inner surface, owing to plastic deformations caused by impact damage, which were primarily caused by delamination and developed from large voids at the site of impact. The hybrid material configuration exhibited a phenomenon where the inner and outer layers minimized cracking in the middle layer, causing plastic deformation to be the primary impact response of the middle layer. Through the analysis processes developed in this work, quantitative assessment of tubular braided composites was achieved by measuring changes in voids caused by impact at the individual level, and by examining the damage profile while accounting for the voids. The methodology can be applied to various material configurations to provide meaningful insight into the effects of hybridization in the impact response of braided composites.

Mechanical properties of interply and intraply hybrid laminates based on jute-glass/epoxy composites

Currently, hybridization of natural-synthetic fibers within a polymeric matrix has received wide attention owing to its promising properties. This study investigated the mechanical properties of interply and intraply hybrid jute (J)-glass (G) fiber/epoxy composites. The mechanical properties (i.e., tensile, flexural, and impact) of the pure jute, pure glass, and their hybrid composites were evaluated. The prepared composite samples consisted of five plies of woven fabrics. Interply hybrid composites comprised three layering sequences: G3JG, GJGJG, and 2GJ2G. Intraply hybrid composites of similar co-woven plies were fabricated by either the alternative replacement of a single glass yarn with a single jute yarn (G1J1) or two jute yarns (G1J2). The results showed that increasing the glass fraction in the interply hybrid composites improved their tensile properties. The two intraply hybrid composites provided almost similar tensile moduli, while the tensile strength of the G1J1 samples was approximately 41% higher than that of the G1J2 counterparts. The maximum flexural properties were provided by 2GJ2G composites, followed by GJGJG, and they were interestingly higher than those of pure glass composites. The G1J1 intraply hybrid composites offered a higher flexural strength and a lower flexural modulus than those provided by the pure glass composites. Compared to the pure glass composites, the impact strengths of the 2GJ2G and GJGJG samples decreased by 4% and 16%, respectively. In summary, the GJGJG hybrid composites exhibited the highest specific tensile, flexural, and impact properties compared to the other hybrid composites.

The effect of multiscale Kevlar/Glass hybridization on the mechanical properties and the damage evolution of 3D orthogonal woven composites under flexural and impact loadings

This work aims to evaluate the effectiveness of inter-ply/intra-tow hybridization in 3D woven composites to achieve an ameliorated impact and flexural performance. In this regard, inter-ply/intra-tow hybrid epoxy composites with Kevlar, E-glass, and ultra-high-molecular-weight polyethylene (UHMWPE) reinforced 3D fabrics are manufactured using the vacuum infusion method. To scrutinize the static and dynamic responses, the produced composites are subjected to flexural and low-velocity impact (50, 100, and 150 J) tests. The findings show that inter-ply hybrid composites exhibit more improved impact and flexural performance than their intra-tow hybrid counterparts. While the elastic moduli and strength values of weft-directional hybrid composites increase, on the contrary, warp-directional counterparts do not display an enhancement in flexural performance. Scanning electron microscopy (SEM) examinations and acoustic emission analysis are conducted together on the bending specimens to understand failure mechanisms leading to observed mechanical responses.

Flexural behavior of carbon/glass inter-ply hybrid FRP composites under elevated temperature environments

Abstract In this research work, the three-point flexural performance of carbon and/or glass inter-ply hybrid epoxy composite by altering the hybrid ratio and stacking position was studied. These materials were tested at various temperatures (30 °C, 50 °C, 70 °C and 110 °C). The test results of hybrid composites results were compared with neat glass/epoxy and carbon/epoxy composites. The stacking position of carbon fibers in hybrid composite plays a vital role while doing a flexural test. Incorporation of two stiffer carbon fibers in glass/epoxy composite i.e., C2G3 and C1G3C1, resulted in a remarkable increment in the case of flexural strength. All composites exhibited ductile behavior at 110 °C. The fractured surfaces revealed the failure mechanism of the composites.

Mode I and II interlaminar fracture toughness of glass/carbon inter‐ply hybrid FRP composites: Effects of stacking sequence and testing temperature

AbstractEven though laminated FRP composites show exceptional performance in various modes of loading, they are susceptible to delamination. The ambient temperature and elevated temperature delamination resistance of glass/carbon fiber interply hybrid composites were assessed via mode I and mode II interlaminar fracture toughness tests performed at 30, 50 and 70°C. Interply hybrid composites performed better than composites with single type of fiber. The fracture toughness of inter‐ply hybrid composites varied with the stacking position. At 30°C, mode I fracture toughness value of alternative glass and carbon fiber stacking sequence (G1C1)5 of hybrid composite showed 40% improvement over 10 layered carbon/epoxy (C10) composite. Further, Mode II fracture toughness of C5G5 composite showed 22% enhancement, and C10 exhibited 42% improvement over 10‐layered glass/epoxy composite. Increasing the test temperature of all composites improved their GIC and GIIC values. The increment in the mode I fracture toughness properties of all composite was in the range of 5%–23% at 70°C from its room temperature value. The fractographic images of fractured samples were studied under a scanning electron microscope and failure mechanisms of composites were identified.

Repeated impact behaviour of inter-ply hybrid aramid/S2-glass epoxy laminates

This paper presents an experimental study on the repeated low-velocity impact behaviour of inter-ply hybrid composites of aramid/S2-glass/epoxy. The impacts were performed using a drop-tower apparatus following ASTM D7136 Standard. Two energies (19 and 37 J) were chosen for the study with up to twenty and five repeated impacts, respectively. A double exponential empirical model is proposed to describe the degradation due to the repeated impacts, considering the hybridization ratio. The impact response and progressive damage are presented and discussed for different laminates: single-fibre, and asymmetric or symmetric hybrids. The results show that hybridization may lead to the mitigation of repeated impact degradation. For asymmetric hybrids, impact on S2-glass showed a combination of higher impact stiffness and lower degradation rate, outperforming single-fibre laminates.

Investigation on Layer Hybridization of Glass/Carbon Fibre Woven Reinforced Composites Subjected to Low-Speed Impact

The present investigation was conducted on the low-speed impact response of quasi-isotropic [±45/0/90°]xs hybrid composite through laboratory level experimental tests. The purpose was to understand the behaviour that the different stacking sequences of hybrid glass/carbon fibre composites has on the ability of the material to sustain loads during low-speed impact events without developing critical structural failure in the material and improving the impact energy absorption properties, which is a relevant matter in aerospace and automotive industries. Drop-weight impact tests were carried out on two different laminates, with different stacking sequences, each of which were 16 symmetric inter-ply hybrid laminates named GC [+45G/−45C/0G/90C]4s and, respectively, G-C [+45G/−45G/0G/90G/+45C/−45C/0C/90C]2s, where G stands for glass fibre and C for carbon fibre. Both were comprised of epoxy matrix reinforced carbon/E-glass fibre woven fabric composites. The outcome of changing the hybrid stacking sequence, on the impact performances, was discussed. The damage morphologies and local failure mechanisms were analysed using visual inspection and a high-resolution laser scanner. Under 33 J impact energy, both tested hybrid composites exhibited approximately 10 kN peak load. Nevertheless, one key parameter, the time to peak load, significantly changed; the damage initiation threshold for GC samples occurred immediately before 6 kN, whereas for G-C samples this threshold appeared much earlier. This type of behaviour was partly connected to the delay in the propagation of delamination and fibre breakage, which was influenced by the high elastic energy absorption of the carbon fibres when compared with the glass fibres. The absorbed energy was higher for GC configuration, whereas a higher DI was observed for samples G-C indicating that a high percentage of the total energy was dissipated through the propagation of in-plane and out-of-plane fibre/matrix cracks. No perforation was observed on either configuration; nevertheless, the damage area significantly changed both in size and appearance from one configuration to another.

Evaluation of tensile properties on glass/carbon fiber epoxy pure, interply, and locally nested intraply hybrid composites

AbstractIn this study, the behavior of pure glass fiber/epoxy, pure carbon fiber/epoxy, interply hybrid, and locally nested intraply hybrid composites under tensile load was investigated. The specimens were produced by the vacuum‐assisted resin transfer molding (VARTM) method. Interply hybrid composites showed approximately the average tensile strength of the glass and carbon fiber/epoxy composites, with 603 MPa. Intraply hybrid composites had 17% lower tensile strength than pure glass fiber/epoxy composites due to the discontinuity of the fibers in the structure. Therefore, pure or interply hybrid composites are suitable in cases where tensile strength is more important, while in special cases where different properties are desired in different regions of a monolithic structure, locally nested intraply hybrid composites can be used. While the finite element analysis (FEA) results of pure and interply hybrid composites were very close to the tensile test, the amount of deviation increased in intraply hybrid composites due to fiber discontinuity. Fiber and void volume fractions of hybrid specimens were found to be around 62% and 1.45%, respectively. The numerical and experimental results of pure carbon fiber/epoxy composite are validated by the analytical solution.

Manufacturing and Characterization of Interply Hybrid Polymeric Biocomposite Material Reinforced with Glass and Carbon Fibers

AbstractThe objective of this study is to investigate the mechanical properties of the polymeric composite hybrid type interply reinforced with glass fibers GF and carbon fibers CF with the structure of the material consisting of: a) three layers CF:GF with the sequence [CF/GF/CF]; b) five layers CF:GF with the sequence: 1) [CF/GF/CF/GF/CF] and 2) [CF/CF/GF/CF/CF]. The GF:CF hybrid biocomposite interply type is made using the working methodology based on the Liquid resin Infusion (LRI) and Vacuum infusion techniques. The general mechanical properties are evaluated experimentally using standard tensile and bending tests using five specimens made according to ASTM standards. Based on the experimental results and the diagrams obtained at the tensile and bending tests of the hybrid polymeric biocomposite type interply comparisons are made regarding the mechanical properties of the composite for each type of structure. The general results confirm, from a mechanical point of view, the usefulness of this type of composite for engineering and biomedical applications.

Influence of hybridization on the mechanical and dynamic mechanical properties of aramid/S2-glass hybrid laminates

This work investigates the effect of hybridization and stacking sequence on the response of S2-glass/aramid/epoxy interply hybrid laminates, focusing on flexural, short beam, dynamic-mechanical results and, especially, quasi-static indentation (QSI) properties. Different laminates of comparable thickness were manufactured by vacuum infusion, one with only aramid fabrics ([K]4S), one with only S2-glass fabrics ([G]8S) and six interply hybrids, namely [G6K5], i.e. six S2-glass layers on top of five aramid layers (asymmetric), [G8K4] [G10K3], [K2G4]S, [G2K]S2 and [G4K2]S. QSI tests were used to determine absorbed energy, maximum energy and peak load, and the in-plane damage was analyzed. Significant differences in mechanical and dynamic-mechanical properties (pairing effect) were observed for the [K2G4]S, [G2K]2S, [G4K2]S and [G8K4] hybrids, and the adhesion factor (A) presented the closest correlation with energy absorption capacity of the laminates. The results have shown that hybridization of aramid composites with S2-glass may enhance impact absorption, and a positive hybrid effect was observed for the laminates with S2-glass fibers on the top surface, [G6K5], with peak load and absorbed energy (9.9 kN and 55 J, respectively) higher than that of the pure laminates [G]8S (5.9 kN and 41 J) and [K]4S (8.6 kN and 46 J).

Isogeometric analysis based on non-uniform rational B-splines technology of stress and failure strength in inter-ply hybrid laminated composite

In the present study, the stress distribution and first ply failure strength of hybrid laminated composites subjected to uniaxial tensile and compression loads are predicted using Isogeometric analysis (IGA) based on non-uniform rational B-splines technology, commonly referred to as non-uniform rational B-splines (NURBS) technology. The obtained results were compared to finite element method results (ANSYS) published in the literature and analytical results using Autodesk Helius Composite software. Graphite-glass/epoxy hybrid composite plates are analyzed for different lamination orientations and used to calculate first ply failure strength. Non-interactive theories such as maximum stress, maximum strain, and fully interactive criteria such as Tsai-Wu, Tsai-Hill and Hoffman are used to predict the failure strength of different laminates. The failure envelopes of the hybrid composites are developed using the same failure criteria used for the graphite-glass/epoxy hybrid composite. The effects of IGA refinement and plate’s dimension on the present analysis were also established. The IGA results showed good accuracy, robustness and good convergence speed with the analytical software results and the finite element method (FEM) reference value.

High Strain-Rate Through-Thickness Compression Testing of Symmetrical Inter-ply Hybrid Polymer Composites Reinforced with Carbon/Glass and Carbon/Kevlar Fibers

High Strain-Rate Through-Thickness Compression Testing of Symmetrical Inter-ply Hybrid Polymer Composites Reinforced with Carbon/Glass and Carbon/Kevlar Fibers

Strain rate effect on the tensile properties of plain weave aramid, carbon, and glass fabric reinforced monolithic and hybrid composites

Abstract The tensile responses of three monolithic composites (aramid, carbon, and glass) and three different interply hybrid composite laminates (aramid/carbon, glass/aramid, and glass/carbon) were studied at quasi-static and intermediate strain rates. Monolithic composites were found to be more sensitive to strain rate than hybrid counterparts. The hybrids with glass layers had the highest sensitivity among the hybrid laminates. Tensile strengths of aramid, carbon, and glass monolithic composites improved by 15.2 %, 10.1 %, and 22.2 %, respectively, as the strain rate was increased from 0.001 s−1 to 10 s−1, while increases in tensile strengths of aramid/carbon, glass/aramid and glass/carbon hybrid laminates were 8.8 %, 17.7 %, and 5.2 %, respectively. Hybridization of glass with aramid gave the highest failure strain gain. Carbon layers located at the centre of the hybrid laminates resulted in increased tensile strength.

Natural frequency and buckling optimization considering weight saving for hybrid graphite/epoxy-sitka spruce and graphite-flax/epoxy laminated composite plates using stochastic methods

In recent years, the use of hybrid composites, in which natural fibers combine with synthetic fibers, in place of composite structures consisting only of synthetic fibers has become increasingly popular due to growing environmental concerns and the need to develop sustainable, more lightweight, recyclable materials required for engineering applications. In this regard, the present paper is an attempt to show the usage of sitka spruce as an alternative to synthetic E-glass fiber and natural flax fiber in design of interply hybrid composite structures in terms of fundamental frequency, buckling resistance and weight. The single-objective and multi-objective approaches are considered to acquire optimum design for non-hybrid and hybrid structures. The modified versions of the optimization methods Differential Evolution (MDE), Nelder Mead (MNM) and Simulated Annealing (MSA) algorithms are considered to solve problems. The results show that the optimum design of the hybrid graphite/epoxy-sitka spruce laminated plate to obtain the structure having a more lightweight (e.g., 53%), higher frequency (e.g., 65%) and buckling resistance (e.g., 90%) was computed and compared with those of the hybrid graphite-flax/epoxy, neat sitka spruce, neat flax/epoxy and neat glass/epoxy laminated composite plates.

Low-Velocity Impact Behavior of Foam Core Sandwich Panels with Inter-Ply and Intra-Ply Carbon/Kevlar/Epoxy Hybrid Face Sheets.

Sandwich composites are extensively employed in a variety of applications because their bending stiffness affords a greater advantage than composite materials. However, the aspect limiting the application of the sandwich material is its poor impact resistance. Therefore, understanding the impact properties of the sandwich structure will determine the ways in which it can be used under the conditions of impact loading. Sandwich panels with different combinations of carbon/Kevlar woven monolithic face sheets, inter-ply face sheets and intra-ply face sheets were fabricated, using the vacuum-assisted resin transfer process. Instrumented low-velocity impact tests were performed using different energy levels of 5 J, 10 J, 20 J, 30 J and 40 J on a variety of samples and the results were assessed. The damage caused by the modes of failure in the sandwich structure include fiber breakage, matrix cracking, foam cracking and debonding. In sandwich panels with thin face sheets, the maximum peak load was achieved for the inter-ply hybrid foam core sandwich panel in which Kevlar was present towards the outer surface and carbon in the inner surface of the face sheet. At an impact energy of 40 J, the maximum peak load for the inter-ply hybrid foam core sandwich panel was 31.57% higher than for the sandwich structure in which carbon is towards the outer surface and Kevlar is in the inner surface of the face sheet. The intra-ply hybrid foam core sandwich panel subjected to 40 J impact energy demonstrated a 13.17% higher maximum peak load compared to the carbon monolithic face sheet sandwich panel. The experimental measurements and numerical predictions are in close agreement.

Improving the mechanical performance and impact damage tolerance of glass composite laminates via multi-scales of hybridisation

The glass fabric composite laminates are widely used in the various applications compared to the non-crimp cross-ply laminates due to their high fracture toughness and better impact damage tolerance. However, their in-plane properties are limited owing to the interlacements of their warps and wefts. In this regard, an experimental investigation of the multi-scales hybridisation (i.e. yarns-hybridisation and hybrid layers methods) for improving the mechanical performance, and impact damage tolerance of continuous glass fibre-epoxy composite laminates has been presented. The two types of composite laminates that have intra yarns (i.e. hybrid yarns) and inter-ply (i.e. hybrid layers) with multi-stacking sequence were manufactured via vacuum infusion process and then compared with 2D hybrid fabrics and glass cross-ply composite laminates with respect to in-plane properties and impact damage tolerance respectively. The tensile strength properties and the low-velocity impact response of all laminates were identified by using tensile strength and drop-weight impact tests at different energy levels. The impact damage tolerance was studied by using compression-after-impact (CAI) strength tests, measuring the residual compressive strength of the damaged laminates. The damage characterisation based on impact and compression, and compression after impact was also examined using scanning electronic microscopy (SEM). The outcome of this investigation demonstrated that the intra- and inter-ply hybrid composite laminates showed higher tensile strength and modulus of elasticity, compared to hybrid fabric composites. Moreover, the impact damage tolerances of intra- and inter-ply hybrid laminates were found to be slightly higher than the non-crimp cross-ply glass laminates for certain-impact energy levels.

Mechanics of deformation and failure of hybrid polymer composites

High performance composites can be designed, and their properties tailored to enhance specific mechanical (or multifunctional) properties of the material. Fibre hybridization, which consists of combining multiple types of fibres in the same composite material, is a strategy that can lead to improved composite properties and performance, as it not only changes the material properties but also  the damage propagation mechanisms leading to final failure. In this work, two numerical frameworks are proposed to analyse the mechanics of failure of hybrid polymer composites. Firstly, a FEM framework is used to analyse the mechanisms that lead to longitudinal failure of composite materials. The effects of superimposed hydrostatic pressure on longitudinal tensile failure is analysed and a generalized reduction in strength with increasing pressure is predicted. Secondly, a dynamic Spring Element Model is proposed and used to analyse the dynamics of the formation of clusters of broken fibres and the effects of fibre dispersion in hybrid composites, concluding that higher fibre dispersion leads to improved material performance. Additionally, an experimental campaign on two different hybrid materials (inter and intratow) is performed to understand the effect of hybridization on fibre dominated properties, namely longitudinal tensile strength and translaminar fracture toughness. The interply hybrid material is obtained by stacking alternating T800 and HR40 thin-ply layers, while the intratow is obtained by combining the two types of fibres in the same layer using spread tow technology. A change in the damage mechanisms through hybridization is observed, which can lead to improved material performance.

Quasi-static perforation response of inter-ply hybrid polypropylene composites at various temperatures

This study is motivated by the lack of knowledge in the research of mechanical characterization of thermoplastic composites (TPCs) with additional fiber hybridization. To enhance the mechanical properties of long glass fiber-reinforced polypropylene (PP) composite, hybridization via alkaline-treated aramid and carbon fabrics is performed. High performance fabrics modified with 10 wt.% sodium hydroxide (NaOH) aqueous solution are incorporated into the PP composite as reinforcements. Herewith, four arrangements (hybrid composites) for two different reinforcements and two different stacking configurations and the monolithic composite are separately investigated in terms of quasi-static perforation behavior. Failure mechanisms are also evaluated at macro level by visual observations and micro scales through a scanning electron microscopy (SEM). The experimental results provide a basis for selecting fiber-enabled hybridization and lay-up configuration with improved perforation resistance. Moreover, the influence of test temperature is reported for three different values as 20°C, 60°C, and 100°C. Based upon the results, the maximum penetration force of hybrid configuration with single-layered aramid fabric reinforcements is approximately 15.5% higher than that of single-layered carbon fabric reinforcements at 60°C test temperature. It is further observed that the absorbed energy improves as the number of fabrics is increased in both aramid and carbon reinforcements. The test temperatures significantly affect the failure mechanisms of TPCs. A smaller damaged area at the penetrated faces of the hybrid structures is obtained by comparison with the monolithic TPCs.