Carbon Fiber Laminate Research Articles

Tree root-inspired structural electrolyte for laminated carbon fiber reinforced composites with high energy density and mechanically-robust properties

Mechanically sturdy electrolytes with high ionic conductivity are the prerequisite for structural energy storage devices, which can store electrochemical energy and withstand mechanical loads, simultaneously. However, suitable structural electrolytes are rarely exploited. Herein, inspired by a tree root network, integrated with high ionic conductivity of poly(vinylidene fluoride-co-hexafluoropropylene) (PVHF) based polymer and high mechanical strength of glass fiber fabric, the structural electrolyte GF/PVHF/KL-Z is designed and fabricated for structural Zn-ions batteries. The structural electrolyte demonstrates the ionic conductivity of 4.4*10-4 S cm−1 and excellent mechanical properties (110 MPa in tensile strength), enabling fast Zn2+ transmission and effective suppression of zinc dendrites. When carbon fiber reinforced laminated structural Zn-ion batteries were fabricated with structural electrolyte GF/PVHF/KL-Z, the structural devices delivered high mechanical strength (bending strength of 584.5 MPa) and energy density of 159.0 Wh kg−1. And after 500 cycles, the capacity retention of about 94.6% is also realized with Coulombic efficiency (CE) of nearly 100%. Importantly, the in situ mechanical-electrochemical tests further verify the multifunctional performance of the structural batteries. Overall, this work opens a pathway to developing safe, low-cost fiber reinforced biomimetic structural electrolytes for structural energy storage devices with excellent mechanical and electrochemical properties.

The Impact of Laminations on the Mechanical Strength of Carbon-Fiber Composites for Prosthetic Foot Fabrication

Carbon-fiber composites are considered to be one of the suitable materials for the fabrication of prosthetic feet. However, commercially available composites-based prosthetic foot designs present several problems for lower limb amputees, such as low tensile strength, reduced impact resistance, high cost, and weight structure. Modulating the mechanical properties of carbon-fiber composites using a simplified method can help reduce these issues. Therefore, our present research aims to identify the impact of increasing the concentration of carbon fiber in the fabrication of carbon-fiber composites by using the hand layup method without the vacuum bagging technique. To improve the mechanical strength of carbon-fiber laminates, an increasing number of carbon-fiber layers are used in sample preparation. This study aims to determine the tensile strength of the laminates with a different number of carbon-fiber laminations. For the preparation of the sample specimen, black 100% 3 K 200 gsm carbon fiber with a cloth thickness of 0.2 mm and tensile strength of 4380 Mpa was laminated with two parts of epoxy resin Araldite® LY556 and Aradur hardener at a ratio of 100:30 to make the test specimen. The results indicated an overall improvement in the tensile strength of carbon-fiber laminates owing to the increase in the number of carbon-fiber layers in successive samples. The maximum achieved tensile strength through the present experimental protocol is 576.079 N/mm2, depicted by a prepared specimen of 10 layers of carbon fiber. Secondly, an increase in the deformation rate has also been observed by increasing the loading rate from 2 mm/min to 5 mm/min during the tensile testing of fabricated samples. These sample carbon-fiber composites can be used in the fabrication of prosthetic feet by controlling the experimental conditions. The fabricated prosthetic foot will assist in rehabilitating lower-limb amputees.

Thermophysical Properties Mapping of Composites by Lock-in Thermography: Applications on Carbon Fiber Reinforced Plastics

We propose a versatile method for measuring the thermophysical properties of composites by means of lock-in thermography (LIT) technique. The method is based on analyzing the thermal response distribution induced by periodic laser heating, which enables simultaneous high-spatial-resolution mapping of the effective out-of-plane thermal diffusivity, thermal conductivity, and volumetric heat capacity over the surface of the material. We validate the method using a reference material and demonstrate its capability in visualizing the effective properties of laminated carbon fiber reinforced plastic and carbon fiber reinforced thermoplastic with discontinuous fibers. The results showed that the LIT-based approach has high reproducibility and sensitivity, which allows observing the effect of fiber orientations on the effective properties. The proposed method will be useful for thermal research in composites, defect detection, and for investigating component geometric arrangement effects on the thermophysical properties.

The mechanical performance of ‘forged’ carbon fiber components

Composite materials manufacturer and distributer Easy Composites investigates into the mechanical properties of compression-molded short-strand carbon fiber laminate, popularly described as ‘forged carbon’.

Plan and Analysis of A Lightweight Composite Transporting Container Made of Carbon Fiber Laminates

The writing demonstrates that a 20% decrease in the heaviness of void 40-foot transporting compartments would result in $28 billion of fuel reserve funds, alongside a 3.6 exajoule decrease in the energy request over holders’ 15-year lifetime. Diminishing the energy interest and subsequently nursery gas outflows by using lightweight steel trailers has been a neglected methodology. In this respect, this study researches the chance of additional lessening the heaviness of an unfilled holder without compromising the primary respectability, strength, and capability of a customary steel compartment. This examination sees that as up to a 80% decrease in weight is conceivable by creating steel trailers with composite materials. This examination presents the new plan of a 40-foot holder made of carbon fiber overlays. The tare weight of a conventional 40-foot transporting compartment is around 3750 Kg. In actuality, in this examination, the heaviness of a composite plan of a similar compartment is determined to be around 822 Kg. Extra tests with different burdens, for example, lifting the compartment and stacking loads onto the composite compartment, are performed to investigate the strength and clasping issues of the plan introduced in this review. The investigations uncover that the composite steel trailer is an exceptionally encouraging possibility for lessening ozone harming substance outflows, giving fuel reserve funds and consequently lessening the functional expenses of transportation.

Monitoring the drilling process of carbon fibre laminates using acoustic emission

This work aims to apply Acoustic Emission to monitor the drilling process in carbon fibre laminates. Continuous Acoustic Emission data is captured over the entire drilling process of a through hole. The use of continuous acoustic emission data acquisition allows the identification of lower frequency periodic temporal features related to the cutting process. A new approach to data analysis is presented that utilises an enveloping technique to study these periodic phenomena and show that they correlate to changes in cutting regime as tool wear advances and hole quality reduces. This analysis of Acoustic Emission data is supported by the measurement of tool temperature, thrust force and the assessment of hole quality. Results show that Acoustic Emission activity is correlated to changes in the cutting process, and a correlation between tool wear and Acoustic Emission is observed. This correlation has been confirmed by corresponding increases in thrust force and drill temperature, with a consequent decrease in the observed hole quality.

Spray deposition of sustainable plant based graphene in thermosetting carbon fiber laminates for mechanical, thermal, and electrical properties

AbstractGraphene has generated substantial interest as a filler due to its exceptional strength, flexibility, and conductivity but faces obstacles in supply and implementation. A renewable, plant‐based graphene nanoparticle (pGNP) presents a more accessible filler with the same properties as mineral graphenes. In this study, we examine the effects of pGNP, which was sprayed on a carbon fiber/epoxy prepreg at loadings from 1.1 to 4.2 g/m2. The study considered the mechanical, thermal, and electrical properties of pGNP‐composite. An even particle dispersion was achieved using a spray application of pGNP in a water/alcohol suspension with the addition of surfactants and dispersion aides. Results show that pGNP addition increases flexural modulus 15%, flexural strength 17%, interlaminar shear strength 17%, and mode I fracture toughness by 146%, as well as increases electrical conductivity 294% and thermal conductivity 24%, with these improvements observed at 1.1–2.3 g/m2 spray loadings.

Synthesis of a phosphorus-based epoxy reactive flame retardant analog to diglycidyl ether of bisphenol A (DGEBA) and its behavior as a matrix in a carbon fiber composite

This paper describes the synthesis of a phosphorus-based flame retardant that is a chemical analog of diglycidyl ether of bisphenol A (DGEBA), as well as its incorporation as a matrix into carbon fiber laminates. Carbon fiber composites, if used for structural applications in mass transport vehicles (aircraft, trains), will require some aspects of improved fire performance to be used safely in those applications. The first phase of work involved the development of two separate synthesis routes to produce the flame retardant monomer, referred to as Phosphorus-DGEBA or simply P-DGEBA. The second step was to determine the viability of the compound's polymerization behavior through various experimental mixing formulations and curing conditions with an aliphatic amine curing agent. Differential scanning calorimetry (DSC) was used to evaluate the curing behavior of P-DGEBA when mixed with DGEBA and an aliphatic amine curing agent and dynamic mechanical analysis (DMA) was used to observe the glass transition temperature (Tg) of the carbon fiber composites. Thermogravimetric analysis (TGA) was also used to investigate the thermal stability and thermal degradation behaviors of the P-DGEBA/DGEBA blends. The final step included the fabrication of composites and their flammability testing using a cone calorimeter. DMA testing for P-DGEBA measured a Tg that was 10 °C higher than a DGEBA based carbon fiber composite, and DSC studies found that the P-DGEBA / DGEBA blend polymerized well with the amine curing agent. The TGA, MCC, and cone calorimeter data yielded mixed results with TGA and MCC suggesting a more condensed phase / char formation flame retardant activity for P-DGEBA, while cone calorimeter suggested a more vapor phase flame retardant activity. Overall, the P-DGEBA shows some promise as a reactive FR for epoxy + carbon fiber composites, but more study is needed.

Stiffness Degradation under Cyclic Loading Using Three-Point Bending of Hybridised Carbon/Glass Fibres with a Polyamide 6,6 Nanofibre Interlayer

The stiffness degradation of hybrid carbon/glass fibre composites are investigated under cyclic loading in three-point bending. The composites are compared to toughened composites interlayered with PA 6,6 nanofibre (veil) and a matrix toughened with 5% rubber particulate. With the incorporation of veil into the hybridised composite, the hybrid interface experienced extensive localised delamination, due to crack deflection, causing longitudinal cracking between the fibre and veil interface. It is observed that delamination was redirected and reduced by veil interlayering, due to crack bridging as the cracks propagated. The carbon fibre composites toughened by rubber particulate showed similar stiffness retention to carbon fibre after 1,000,000 cycles. The veil interlayering within carbon fibre improved the stiffness retention by 66.87% for the flexural modulus, compared to carbon fibre and rubber toughened carbon fibre laminates. In both glass and carbon fibre samples, the stiffness retention with veil showed a 10-fold increase in fatigue life, compared with untoughened controls. It is observed from the failure mechanics that veil acted as a randomly orientated fibre layer, rather than a matrix toughener.

Wave dispersion characteristics of laminated carbon fiber reinforced polymer composite shells resting on viscoelastic foundations under thermal field

Wave dispersion characteristics of laminated composite shells resting on viscoelastic foundations in thermal environments are examined. Three types of temperature distributions (i.e., uniform, linear, and sinusoidal) along the thickness of the laminates are considered. Effective material properties of the carbon fiber reinforced polymer (CFRP) composite are calculated by the Mori-Tanaka homogenization method. The four-variable higher-order shear deformation theory (HSDT) and Hamilton principle are utilized to derive the equations of motion. The Navier approach in conjunction with wave solution is exploited to obtain the dispersion relations of the simply supported laminated shells with cross-ply and antisymmetric angle-ply arrangements. A comparative study is performed to demonstrate the validity of the present model. A parametric study is conducted with focus on the effects of curvature ratio, viscoelastic foundation parameters, carbon fiber volume fraction, number of layers, lamination scheme, temperature distribution, temperature difference, and fiber orientation on the wave dispersion behavior. Numerical results manifest that uniform temperature distribution reduces the phase velocity furthest. At low wave number, the extrema of phase velocity are determined by the curvature ratio and fiber orientation. The results can be used for the ultrasound detection techniques and structural health monitoring.

Effect of Interlaminar Toughness on the Residual Compressive Capacity of Carbon Fiber Laminates with Different Types of Delamination

In this paper, the effect of interlaminar properties and the type of delamination defects on the residual compression properties of carbon fiber laminates were experimentally investigated. A new method, which employed magnetic force to guide the arrangement direction of stainless steel particles between layers of laminates, was adopted to improve the interlayer toughness. The digital image correlation, C-scan, and micro-CT were used to measure and identify the compression failure damages. Test results showed that the compressive strength of the intact carbon fiber laminates was 299.37 MPa, and the one of specimens containing the deeply buried delamination, the through-width delamination, and the surface delamination decreased by 55.98 MPa, 58.69 MPa, and 60.23 MPa, respectively. The compressive strength of the specimens containing the deeply buried delamination only decreased by 14.01 MPa when the mode I toughness increased by 81.88%, and the specimen containing the surface delamination only decreased by 30.86 MPa when the mode II fracture toughness increased by 87.72%. However, improving the fracture toughness could not strengthen the specimens containing the through-width delamination. Moreover, a qualitative dynamic damage relationship, which described the relationship between delamination expansion and compression damage vividly, was proposed. The reason the increase of the toughness could improve the residual compression performance of the laminates containing delamination was that the higher fracture toughness hindered the secondary expansion of the delamination during the compression process so that the delamination area could almost remain unchanged.

Study of air-backed and water-backed carbon fiber composite plates subjected to underwater shock loading

A collection of experimental and numerical studies was conducted for laminated carbon fiber composite plates of different layup orientations to investigate their response and failure when subjected to underwater shock loading. The composite plates were clamped within a rigid fixture and submerged within an anechoic water tank while having either an air-back or water-back supporting condition. Plastic bottles partially filled with liquid nitrogen were used to generate shock pressures whose characteristics were closer to that resulting from the pulsation of a gas bubble rather than the detonation of an explosive. A multiphysics model based on fluid–structure interaction was considered for the numerical study. A multiscale approach was also used for the numerical study to predict failure based on the constituent material level (i.e., fiber and matrix material level). Both experimental and numerical results agreed well, indicating that the water-backed carbon fiber plate had a very localized failure while the air-backed composite plate showed global failure. The critical stand-off distance for the failure of the water-backed carbon fiber composite was approximately half of that for the air-backed composite plate of the same layup orientation. In other words, the water-backed carbon fiber composite plate had greater damage tolerance than the air-backed plates.

Flexural Strengthening of Prestressed Girders with Partially Damaged Strands Using Enhancement of Carbon Fiber Laminates by End Sheet Anchorages

This paper examines the impact of flexural strengthening on the percentage of damaged strands in internally unbonded tendons in partially prestressed concrete beams (0, 14.28%, and 28.57%) and the recovering conditions using CFRP composite longitudinal laminates at the soffit, and end anchorage U-wrap sheets to restore the original flexural capacity and mitigate the delamination of the soffit of longitudinal Carbon Fiber Reinforced Polymer (CFRP) laminates. The composition of the laminates and anchors affected the stress of the CFRP, the failure mode, and thus the behavior of the beam. The experimental results revealed that the usage of CFRP laminates has a considerable impact on strand strain, particularly when anchors are employed. The EB-CFRP laminates increased the flexural capacity by approximately 13%, which corresponds to strand damage of 14.28%, while flexural capacity increased by 9.3%, strand damage increased by 28.57% for members strengthened with laminates only, and around 21.58% and 16.85% for members reinforced with laminates and end anchorings. Quasi-experimental equations have been proposed to estimate the actual stress of untethered tendons considering the effect of CFRP laminates and final fixation winding.

Performance of polylactide biopolymer as matrix material for woven fiber composite laminates

The first purpose of this study was, as the first time in the literature, to investigate usability of polylactide (PLA) biopolymer as the matrix of high-performance composite laminated structures having woven forms of glass and carbon fibers. For this purpose, 2-14 layers of 2 × 2 twill Carbon Fiber (CF) and 1 × 1 plain weave Glass Fiber (GF) forms were stacked by PLA powders followed by consolidation of these layers by compression molding technique. After conducting various tests and analysis it was observed that significant improvements in the mechanical and thermal properties could be obtained by laminating PLA with woven CF and GF layers. For instance, mechanical properties obtained for PLA/CF laminates with 14 layers were flexural strength of 641 MPa, flexural modulus of 34 GPa and interlaminar shear strength of 38 MPa. Another purpose of this study was to compare mechanical performance of the PLA matrix laminates with Epoxy matrix laminates having exactly the same type and number of GF and CF layers. It was revealed that mechanical properties of the PLA/CF laminates were approaching to the values of the Epoxy/CF laminates (e.g. flexural strength of 607 and 673 MPa, respectively); while due to poor adhesion between the PLA matrix and Glass Fiber surfaces, the properties were lower in the PLA/GF laminates (e.g. flexural strength of 302 and 553 MPa, respectively). Therefore, it could be generally concluded that, in terms of mechanical performance; traditional thermoset Epoxy matrix could be replaced with the renewable biopolymer PLA matrix in the Woven Carbon Fiber laminates. For the Woven Glass Fiber laminates, a proper sizing treatment with a PLA compatible silane coupling agent would be necessary.

Design and Analysis of MataMorph-3: A Fully Morphing UAV with Camber-Morphing Wings and Tail Stabilizers

Conventional aircraft use discrete flight control surfaces to maneuver during flight. The gaps and discontinuities of these control surfaces generate drag, which degrades aerodynamic and power efficiencies. Morphing technology aims to replace conventional wings with advanced wings that can change their shape to control the aircraft with the minimum possible induced drag. This paper presents MataMorph-3, a fully morphing unmanned aerial vehicle (UAV) with camber-morphing wings and tail stabilizers. Although previous research has presented successful designs for camber-morphing wing core mechanisms, skin designs suffered from wrinkling, warping, or sagging problems that result in reduced reliability and aerodynamic efficiency. The wing and tail stabilizers of MataMorph-3 feature hybrid ribs with solid leading-edge sections that house servomotors, and compliant trailing-edge sections with integrated flexible ribbons that are connected to the servomotors to camber-morph the ribs. Thin laminated carbon fiber composite skin slides smoothly over the compliant rib sections upon morphing, guided by innovative trailing-edge sliders and skin-supporting linkage mechanisms strategically located between the ribs. Sample prototypes were built and tested to show the effectiveness of the proposed design solutions in enabling smooth camber-morphing. The proposed design provides a better alternative to stretchable skins in morphing airplane designs through the concept of skin sliding.

Microscopic testing of carbon fiber laminates with shape memory epoxy interlayer

For the first time, microscopic testing has been performed on shape memory polymer composites (SMPCs) which were manufactured by commercial materials already used in aerospace. Results from micro-tests have been compared with those from conventional memory-recovery cycling on macro-scale. Two shape memory polymer composite (SMPC) laminates were fabricated with different shape memory (SM) interlayer: one in the form of an uncured epoxy powder and the other in the form of a thin epoxy foam. The latter, in particular has been studied to evaluate lightweight and stiff sandwich structures with SM properties. The assessment of the manufacturing process by a hot press moulding technique was assessed through micro scale analysis using SEM and MicroCT analysis. DMA analyses were carried out to understand the interaction mechanisms between raw constituents. A Vickers micro-indentation examination before and after heating was able to assess the shape recovery behaviour at the micro-scale level. A nano-instrumental indentation was used to characterise the shape memory response under different loads at elevated temperatures. Whilst an instrumented thermo-mechanical test allowed to investigate the shape memory behaviour at macro-scale level. Results allow identifying the recovery mechanisms at the micro-scale which are responsible for the shape memory performances at the macro-scale. The higher recovery ability of the SM foam is confirmed in comparison with bulk interlayers.

Design, manufacturing and FEA prediction of the mechanical behavior of a hybrid-molded polycarbonate / continuous carbon fiber reinforced composite component

In this paper, we report a study regarding the design, manufacturing and finite element analysis (FEA) prediction of the mechanical behavior of a thermoplastic matrix/carbon fiber reinforced composite (CFRC) component. The CFRC component is constituted by a continuous carbon fiber laminate impregnated with a polycarbonate (PC) matrix, with edge and ribs overmolded with unfilled PC. The component has been manufactured by the one-step process (composite hybrid molding), with the use of rapid heat cycle molding (RHCM) to improve the surface quality. The flexural behavior has been predicted by an integrated FEA model approach, which considers the mechanical response of the composite laminate and the structural contribution of the overmolded ribs. As a result, a significant reduction of the surface roughness (Ra value decreases from 0.43 to 0.06 μm) was obtained thanks to the use of RHCM process. Moreover, the developed FEA model was able to predict the flexural behavior of the CFRC component with high accuracy (FEA maximum load 1.6% higher than the experimental value).

Comparative modal analysis of B70 and LCR-6 type railway sleepers after repeated impact loads

Due to today's high-frequency trainloads and wheel or rail irregularities, the railway system is more exposed to impact loading conditions. In this study, laminated carbon fiber reinforced polyurethane (L-CFRPU) products were used, with a new non-pre-stressed production process, to improve the impact damping characteristics of concrete railway sleepers. New designed LCR-6 type sleepers were compared with standard B70 type pre-stressed concrete sleepers by performing modal analysis before and after a 50 times repeated-330 kN impact loading procedure. This is the first study to compare new LCR-6 type sleepers with prestressed competitors after impact loads. According to the analysis results, FRF magnitude values ​​decrease up to 83% lower in impacted LCR-6 type sleepers compared to impacted B70 type sleepers. After the impact loading procedure, the cracks formed in LCR-6 type sleepers closed and remained below 50-µm width, and according to the simultaneous mechanical test results, these few hairline cracks do not cause a significant mechanical capacity loss, while increasing the damping ratios by 274%. This advantage will be beneficial in extending the service life of sleepers and protecting other railway components from vibration and impact damage. Therefore, while the pre-stressed concrete sleepers have a negative course during their service life, the non-pre-stressed LCR type sleepers show a positive acceleration.

Influence of carboxylated multi-walled carbon nanotube on the thermostability, and viscoelastic properties of poly (ether imide)/carbon fiber laminates

Carbon nanotubes have boosted research in several areas, especially in nanostructured thermoplastic composites. This work comes as its most significant contribution, the processing, and evaluation of the influence of the multi-walled carbon nanotubes (MWCNT) content on the viscoelastic, thermal stability, and flammability behavior of poly (ether imide) (PEI)/carbon fiber laminates. MWCNT favored an increase in composites' thermal stability, however, the pyrolysis temperature was not influenced by MWCNTs, and a reduction in pHRR (peak of heat release rate) and THR (total heat release) were observed. From DMA, despite the reduction in glass transition temperature (Tg), there was an increase of the storage modulus, an increase in the interphase region, and a more outstanding contribution to the viscoelastic properties from the MWCNT addition. TTS analysis also showed an enhancement of long-term stability when carbon nanotubes were added.

Reconsolidation effect on impact, compression after impact and thermal properties of poly (aryl ether ketone) composites for aeronautical applications

The purpose of this work is to evaluate the reconsolidation of a carbon fiber composite with poly (aryl ether ketone) (PAEK)/carbon fiber laminates after suffering impacts from different energy levels (5, 10 and 30 J) and being restored by reconsolidation. For this comparison, thermal analysis, and compression after impact tests were performed to evaluate the properties of the material before and after the reconsolidation process. According to the found results, it was observed that with small damages it is possible to fully recover the material after new consolidation and for larger damages there is also a partial recovery compared to the base laminate. The material remains thermally stable in all situations, in other words, its thermal properties remain even after impact tests and reconsolidation process.