Plain Weave Carbon Research Articles

Damage evaluation in plain-woven CFRP plate with circular hole under cyclic tensile loading using electrical impedance tomography

Understanding and predicting damage progression within thin plain-woven carbon fiber-reinforced polymer (CFRP) components is an essential issue for scheduling maintenance intervals and structural inspections and typically requires extensive test series. However, uncertainties always remain and result in conservative design and unnecessary downtimes due to the repeated inspections of a healthy structure. Structural health monitoring (SHM) can be used to reduce these uncertainties, as it allows one to evaluate the condition of a mechanical structure during operation. Numerous SHM methods have been developed, which achieve different levels of damage identification but are often investigated at small coupons with nonrealistic structural damages and loading conditions on both structure and sensor. The present research investigates electrical impedance tomography (EIT) featuring an elastoresistive thin-film sensor to evaluate damage that propagates from a circular hole in a large plate under cyclic tensile–tensile multiblock loading. Applied fatigue loads were increased multiple times up to a total number of two million cycles. During the loading, damage initiated at the hole and continuously propagated into the plate. Repeated EIT evaluations of the applied sensor and validating evaluations by means of digital image correlation clearly revealed the robustness of the hardware and the potential of the SHM method for damage evaluation of plain-woven CFRP components.

Mixed Mode‐I/II interlaminar fracture toughness Characterization of woven Carbon–Kevlar interyarn hybrid textile composites

AbstractIn actual service conditions, the composite structures are subjected to the combined effect of Mode‐I and Mode‐II loadings. It has great significance in the aerospace, defense, military, automobile, and marine sectors. This study aims to determine the Mixed Mode‐I/II interlaminar fracture toughness (ILFT) of plain and twill woven carbon, Kevlar monolithic, and interyarn hybrid textile composites under several hybridization schemes. The tailored properties are obtained using the interyarn hybridization of high stiff carbon yarn and high tough Kevlar yarn. The effect of individual yarn in the length direction in different hybrid composite laminates is carefully investigated. The Mixed Mode‐I/II ILFT characterization is experimentally performed using a mixed mode bending (MMB) test specimen on the Instron 8862 system under 45%, 55%, and 65% Mixed Mode ratios (MMRs). The increase in mode mixture percentage decreases the lever length, increases the load‐bearing capacity, and increases the Mixed Mode‐I/II ILFT of the MMB test specimen. Plain woven composites exhibited a higher ILFT than twill woven textile composites. The plain woven carbon–Kevlar hybrid composite laminate with carbon yarn‐in‐length direction shows the highest Mixed Mode‐I/II ILFT after CP laminates. Hybridization significantly increases the Mixed Mode‐I/II ILFT compared to monolithic Kevlar fabric‐reinforced composites. Moreover, the failure mechanisms are investigated using scanning electron microscopy.Highlights Mixed Mode‐I/II ILFT of carbon–Kevlar interyarn hybrid textile composites. ILFT at nonlinearity (NL), VIS, and 5%/Max load points for 45%, 55%, and 65% MMR. Advantage of placing carbon yarn‐in‐length direction in hybrid configurations. Effect of carbon–Kevlar interyarn hybridization on Mixed Mode‐I/II ILFT. Fractography of tested specimens to investigate several failure mechanisms.

Effects of high temperature and strain rate on the impact-induced inter-laminar shear behavior of plain woven CF/PEEK thermoplastic composites

This paper aims to investigate the interlaminar shear properties and failure mechanisms of plain woven carbon fabric/polyetheretherketone (CF/PEEK) thermoplastic composites under high strain rate impact loads at different temperatures (25°C, 120°C, 295°C). A reliable hot air flow heating method with SHPB is creatively employed for short beam shear experiments. A multi-scale model was developed to predict the impact behavior of plain CF/PEEK composites. Both results show that the thermoplastic composites have strong strain rate and temperature dependence, and which are more sensitive to temperature effect. As the temperature increases, the thermoplastic composites are mainly affected by the softening effect of the matrix due to the glass transition temperature. The shear modulus and peak stress appear to decline at high temperatures, while the failure strain tends to increase. The damage mode changes from interlayer delamination cracking at the glassy state to shear fracture and fiber pullout at a highly elastic state. As the strain rate increases, the failure strain decreases, while the shear modulus and peak stress show the opposite trend. Fiber bundle breakage, debonding, matrix cracking, and significant interlayer delamination occur at high strain rates.

Using carbon fiber tape to tailor the coefficient of thermal expansion in 3D-Printed composite tooling

In this work, we investigated the effect of plain woven carbon fiber tape embedded in each layer of an additively manufactured part on the coefficient of thermal expansion (CTE) and compared it to conventionally printed parts. Current advancements in Additive Manufacturing enable cost-efficient 3D printing of composite tools. However, these tools do not yet offer a low CTE comparable to Invar, necessary for producing aerospace-quality composite parts. Using the novel Advanced Tape Layer Additive Manufacturing process, the tape is placed on top of the bead immediately after extruding the short fiber-reinforced material. The samples are compared to Material Extrusion specimens from a Large Format Additive Manufacturing System. A lower CTE was achieved within the printing plane. Micro-computed tomography images correlate the preferential orientation of short fibers with measured CTE values. The CTE modification can match the part CTE to the tool CTE and therefore optimize the quality of manufactured parts.

Random and harmonic responses of plain woven carbon fiber reinforced conical-conical shell based on machine learning multiscale modelling

This study analyzes the frequency-response characteristics under non-stationary base random acceleration and harmonic points force excitations of plain woven carbon fiber reinforced polymers (PW-CFRP) conical-conical shells comprehensively. Artificial neural network (ANN) based machine learning multiscale modelling strategy is introduced in the process of predicting the mechanical properties of PW-CFRP. The dataset is generated by randomization, linear fitting and two-step homogenization and then trained to generate an ANN to predict the mechanical properties of PW-CFRP. The governing equations of the conical-conical shell under random acceleration excitation are obtained according to the first order shear deformation theory (FSDT) and Hamilton's principle. After the structure is split along the circumference at the excitation points, the harmonic points force excitations are introduced based on the discontinuity condition between conical segments. Generalized differential quadrature (GDQ) is applied during the solving procedure. After comparison studies focusing on the frequency-response characteristics under two types of excitations, two examples on harmonic and random responses of conical-conical shell and conical-cylindrical shell are carried out separately. In this process, the effects of excitation type, excitation and response points, geometric parameters on the frequency-response characteristics are extensively analyzed, which proves efficiency and accuracy of the ANN based machine learning multiscale modelling strategy and the constructed GDQ based computational strategy.

Quasi-static and dynamic behavior analysis of 3D CFRP woven laminated composite auxetic structures for load-bearing and energy absorption applications

This paper investigated the quasi-static and dynamic behavior of 3D auxetic metamaterial structures made from carbon fiber reinforced polymer (CFRP) laminated composite. The aim of the study was to enhance design methodologies for load-bearing and energy absorption applications of these 3D novel structures, filling the research gap in understanding their response to quasi-static and especially dynamic loadings. The two novel 3D structures were designed and fabricated by using an interlocking assembly method based on the 2D auxetic CFRP sheets, which were formed with hybrid double-arrow-head with re-entrant and star unit-cells and made with plain weave carbon epoxy prepregs. The finite element (FE) method was adopted to analyze the mechanical characteristics of the structures under the quasi-static and dynamic loading, and Hashin failure criteria were used to define damage in the structures. The study showed that the designed 3D auxetic CFRP structures simultaneously exhibit superior auxeticity, load-bearing, and energy absorption capacity.

Resistivity model of carbon fiber cloth considering the effect of interlayer contact resistance

A resistivity model of a plain-woven carbon fiber dry cloth that considers the interlayer contact resistance is proposed for induction heating and welding analysis of carbon fiber reinforced thermoplastics. Although the cloth, which is regarded as a single-layer thin plate, does not exhibit homogeneous resistivity, homogenized effective thin-shell resistivity is required to analyze the thin-shell complex structures of aircraft. The influence of the direction angle and strip width on the effective resistivity can be expressed using this model. The mechanism for the generation of a large difference in resistivity between the 0° and 45° directions of the cloth is clarified. The proposed model is verified through comparison with experimental results. According to the induction heating experiments, the overall temperature distribution of the cloth is predicted well by the shell finite element analysis using the effective resistivity.

The effect of imperfect bonding on stress distribution in fibrous composites

An attempt was made to map the distribution of stress in fibrous composites with imperfect bonding. Two analytical micro-mechanics models were developed. In the first model, the composite was subjected to axial tensile loading, parallel to the fiber direction, and the assumption of iso-strain was employed to derive the control equations. In the second model, the composite was loaded in the direction transverse to the fiber. An iso-stress condition was employed, and Airy stress function was utilized to articulate the stress and displacement equations. An assumption of how the stress is transferred between the matrix and the fiber was introduced in both models. To investigate and validate the models, specimens were fabricated using a carbon plain weave fabric and a geopolymer matrix. Single fiber pullout and three-point bending tests were carried out. The maximum average tensile stress obtained from the three-point bending tests, as well as the mechanical properties of the fiber and geopolymer, served as input for the models. Results indicate that the effect of the level of bonding is very high in the transverse direction while almost negligible in the axial direction. The difference in the maximum value of the axial tensile stress at the fiber-matrix interface was used to calculate the numerical value of the interfacial shear strength, and the numerical result matched the data obtained from the single fiber pullout test.

Novel method of multiaxis weaving and impact analysis of the ensuing composites

The study aims to develop a novel method of weaving multiaxis preform on conventional weaving machines and analyse impact tolerance of the ensuing composites along with development of finite element analysis model. An extra set of 200 tex carbon fibres, referred as bias fibres, were integrated into carbon fibre plain woven fabric during the weaving stage on a conventional closed reed weaving machine. This was achieved by partial carbon fibre weft insertion at regular intervals from both edges of the fabric. The multiaxis preform was used as ply on top of plain woven carbon fabric plies, each of 160 g per square meter aerial density. The carbon fibre composites were manufactured by infusing bisphenol F epoxy resin as a matrix and 4 plies of carbon fabric by hand layup method. The composites were subjected to low-velocity impact loading at 0.4 m height of 5.12 kg impactor, and force-time history was recorded by the piezoelectric transducer. A comparison of impact loading results showed that the multiaxis woven composites increase impact strength by 18.3% due to the reinforcement of bias fibre. Based on the test results, a finite element analysis model was developed in Ansys v.19 to simulate the stress distribution during impact loading of the multiaxis woven composites.

Damage Propagation and Residual Strength of Simple Block-Loaded CFRP Plates with Circular Holes under Tension–Tension Fatigue Conditions

Holes and their effects on the fatigue behavior and damage propagation of thin-walled structural components remain objects of research. In this paper, the previously untreated effect of round holes in thin plain-woven carbon fiber-reinforced plastic plates subjected to simple block loading is examined, and the implication on both damage propagation and residual tensile strength is investigated. Using three-dimensional digital image correlation, the damage propagation in the performed experimental tests is acquired, and the damage size is quantified. The evaluations reveal a relationship between the damage propagation and applied load level, for which an empirical model has been previously established by the authors. As the number of cycles increases, a saturation behavior is found. Once the increased load is imposed on the plate, damage propagation resumes, leading to further damage propagation that can be described with the same empirical model as the initial damage propagation, including renewed saturation behavior. The subsequent experimental tests to determine the residual tensile strength reveal a positive effect of the existing damage size, as the ultimate load significantly exceeds the ultimate load of the non-damaged plate.

Transition of in-plane compressive strength and failure mechanism of 2D-C/SiC: Influence of off-axis loading angle and loading rate

In this study, the in-plane compressive behavior of two-dimensional plain-woven carbon fiber-reinforced silicon carbide composite (2D-C/SiC) was investigated using on- and off-axis compression experiments under both quasi-static and dynamic loading conditions. The failure mechanisms were elucidated through in-situ observations and microanalysis-based methods. As the loading angle increased from 0 to 45°, stress–strain curves exhibited stronger nonlinearity, and the in-plane compressive strength decreased by 50.2% and 41.1% under quasi-static and dynamic loading conditions, respectively. The failure mechanism shifted from fiber-dominant to interface- and matrix-dominant as the loading angle increased, which was responsible for the strength degradation and intensified nonlinearity in curves. A positive strain rate effect on the in-plane compressive strength attributed to the interface enhancement and multiple crack propagation was identified. Additionally, owing to the competition between the dynamic strengthening and damage aggravation effects, the strain-rate sensitivity factors increased with the loading angle up to 30° and then decreased at 45°.

On the mixed mode I/II translaminar fracture of plain-weave carbon, E-glass and Kevlar reinforced laminated composites

The main aim of this study is to investigate the influence of long fiber types on the translaminar fracture behvior of epoxy-based composites subjected to pure mode I, mixed mode I/II and pure mode II using a combined experimental study and finite element (FE) analysis. Compact tension shear (CTS) test configuration was used to determine the critical strain energy release rate (CSERR) of the laminated composites reinforced with three types of high-performance fibers: Carbon, E-glass and Kevlar fiber. We believe that this is the first published report on the full combination of mode I, mixed mode I/II and mode II translaminar fracture toughness of laminated composites reinforced by three types of fiber. The translaminar fracture envelopes of the tested materials were illustrated. The results revealed that the translaminar CSERR of the composite systems is strongly dependent on the reinforcement type and the loading condition. The mode I translaminar CSERR of E-glass, Carbon and Kevlar fiber reinforced composites are equal to 16.87, 13.52, and 18.29 kJ/m2, respectively. Besides, under mode II loading condition, the translaminar CSERR of the laminated composites reinforced by E-glass, Carbon and Kevlar is obtained as 15.21, 7.82, and 8.45 kJ/m2, respectively. Fractographic analysis manifested that fiber pull-out clustering, fiber splitting, fiber breakage and matrix cracking are the main energy dissipating mechanisms happened on the fracture surface of the laminated composites.

Shape memory effect in polyimide-based composites with multiple driving methods

Shape memory polymers and composites have potential in many application fields as a kind of smart materials with excellent shape memory properties. Herein, two shape memory polyimides (SMPIs) were prepared via thermal imidization process. Furthermore, shape memory composites (SMPCs) were obtained via solution impregnation and compression molding methods using SMPI as the polymer matrix and carbon plain weave fabric as the reinforcement. These polyimides and composites possessed superior shape memory behavior (shape memory recovery ratio, Rr, of SMPI 1 and HO-SMPC-40%: 99.1% and 90.6%). Remarkably, both of these samples maintained stable cyclic and bending shape memory performances. In addition, the composites were endowed with electrical-induced shape memory characteristics owing to their great conductivity. The SMPCs work effectively as deformable lightweight devices, which they could produce shape memory effect in different degrees reflecting to different applied power levels (Rr of HO-SMPC-40% under the power of 10 W and 20 W: 33% and 72%, respectively). These smart SMPIs and SMPCs exhibit flexible deformation properties that extend the potential use of polyimides and their composites to applications such as lightweight deformable sensors for the exploration industry.

An Experimental Investigation of the Mechanical Performance of EPS Foam Core Sandwich Composites Used in Surfboard Design.

Surfboard manufacturing has begun to utilise Expanded Polystyrene as a core material; however, surf literature relatively ignores this material. This manuscript investigates the mechanical behaviour of Expanded Polystyrene (EPS) sandwich composites. An epoxy resin matrix was used to manufacture ten sandwich-structured composite panels with varying fabric reinforcements (carbon fibre, glass fibre, PET) and two foam densities. The flexural, shear, fracture, and tensile properties were subsequently compared. Under common flexural loading, all composites failed via compression of the core, which is known in surfing terms as creasing. However, crack propagation tests indicated a sudden brittle failure in the E-glass and carbon fibre facings and progressive plastic deformation for the recycled polyethylene terephthalate facings. Testing showed that higher foam density increased the flex and fracture mechanical properties of composites. Overall, the plain weave carbon fibre presented the highest strength composite facing, while the single layer of E-glass was the lowest strength composite. Interestingly, the double-bias weave carbon fibre with a lower-density foam core presented similar stiffness behaviour to standard E-glass surfboard materials. The double-biased carbon also improved the flexural strength (+17%), material toughness (+107%), and fracture toughness (+156%) of the composite compared to E-glass. These findings indicate surfboard manufacturers can utilise this carbon weave pattern to produce surfboards with equal flex behaviour, lower weight and improved resistance to damage in regular loading.

Synergy of carbon fiber fabric-based heating element and h-BN modified insulated film on resistance welding of thermoplastic composites

A sandwich-structure heating element (HE) of hexagonal boron nitride (h-BN) decorated polyetherimide (PEI) and plain weave carbon fiber fabric (CFF) of different fabric weight was fabricated to bond carbon fiber reinforced polyetherimide (CF/PEI) laminates by resistance welding. The effects of fabric weight of CFF and thermal conductivity of insulating films on the lap shear strength (LSS) of resistance welding joints and failure mode of CF/PEI composites were investigated. The LSS of the composite joints increased by 31.4% due to the improvement the thermal conductivity of PEI composite film, as well as the reduction of the current leakage during welding process. Intralaminar failure of joints and breakage of carbon fibers of CFF in HE was observed.

Numerical investigation of the Mode I/Mode II fracture behavior of the hybrid composite joints with a hybrid bondline

In this study, the fracture behavior of fracture characterization bonded joints consisting of hybrid composite adherends and hybrid bondlines under Mode I and Mode II loadings were investigated numerically. Numerical analysis was performed using LS-DYNA. Hybrid composite laminates (HCGFRE) obtained by sequencing plain woven glass fiber reinforced epoxy (GFRE) and plain woven carbon fiber reinforced laminates (CFRE) as adherends. Araldite AV138M and Araldite 2015 epoxy adhesives were also used to create the hybrid bondline. Mode I and mode II fracture behaviors were determined by numerical modeling of the Double Cantilever Beam (DCB) and End Notched Flexural (ENF) tests, respectively. In the numerical model, firstly, the fracture parameters of the relevant adhesives were found in the literature, and verification was made utilizing the numerical model. Then, the fracture behavior in both two modes was examined by forming a hybrid bondline. In the literature, there are restricted studies examining the fracture behavior of fracture characterization bonded joints with hybrid bondlines. Additionally, it is not encountered any study determining the both mode I and mode II fracture behavior of composite fracture characterization bonded joints with hybrid bondlines. Therefore, it is thought that this study will gain significant novelties to the existing literature.

Experimental and numerical investigation of mechanical behavior of plain woven CFRP composites subjected to three-point bending

The mechanical behavior of plain woven Carbon Fiber-Reinforced Polymer (CFRP) composites under Three-Point Bending (TPB) is investigated via experimental and numerical approaches. Multiscale models, including microscale, mesoscale and macroscale models, have been developed to characterize the TPB strength and damages. Thereinto, Representative Volume Elements (RVEs) of the microscale and mesoscale structures are established to determine the effective properties of carbon-fiber yarn and CFRP composites, respectively. Aimed at accurately and efficiently predicting the TPB behavior, an Equivalent Cross-Ply Laminate (ECPL) cell is proposed to simplify the inherent woven architecture, and the effective properties of the subcell are computed using a local homogenization approach. The macroscale model of the TPB specimen is constructed by a topology structure of ECPL cells to predict the mechanical behavior. The TPB experiments have been performed to validate the multiscale models. Both the experimental and numerical results reveal that delamination mainly appears in the top and bottom interfaces of the CFRP laminates. And matrix cracking and delamination are identified as the significant damage modes during the TPB process. Finally, the quasi-static and dynamic behaviors of plain woven composites are discussed by comparing the results of Low-Velocity Impact (LVI) and TPB simulations.

Fatigue and Wear Performance of Autoclave-Processed and Vacuum-Infused Carbon Fibre Reinforced Polymer Gears

This study focuses on investigating the fatigue and wear behaviour of carbon fibre reinforced polymer (CFRP) gears, which have shown promising potential as lightweight and high-performance alternatives to conventional gears. The gears were fabricated via an autoclave process using an 8-layer composite made of T300 plain weave carbon fabric and ET445 resin and were tested in pair with a 42CrMo4 steel pinion and under nominal tooth bending stress ranging from 60 to 150 MPa. In-situ temperature monitoring was performed, using an infrared camera, and wear rates were regularly assessed. The result of the wear test indicates adhesive wear and three-body abrasion wear mechanisms between the CFRP gears and the steel counterpart. A finite element analysis was performed to examine the in-mesh contact and root stress behaviour of both new and worn gears at various loads and a specified running time. The results point to a substantial divergence from ideal meshing and stress conditions as the wear level is increased. The fatigue results indicated that the CFRP gears exhibited superior performance compared to conventional plastic and composite short-fibrous polymer gears. The described composite gear material was additionally compared with two other composite configurations, including an autoclave-cured T700S plain weave prepreg with DT120 toughened resin and a vacuum-impregnated T300 spread plain weave carbon fabric with LG 900 UV resin. The study found that the use of the T700S-DT120 resulted in additional improvements.

Buckling in rectangular hybrid composite plates with angled groove-shaped cut-outs

Abstract In this paper, eight-layer composite laminates were produced using twill and plain woven glass and carbon laminate fibers as a reinforcement element and as a matrix with epoxy resin. All laminates having the layup of [(0°/90°)2]s but the hybrid laminate arrangement varies between the number of woven glass and carbon laminates. The buckling behaviour of woven composite laminates used for typical of the aerospace industry is investigated. Un-grooved and grooved with centered elliptical groove angles with 0°, 15°, 30°, 45°, 60°, 75° and 90° specimens were subjected to buckling tests. It was investigated how the woven type, laminate designation, and groove angles affect the buckling behaviour. Cut-out causes to decrease of buckling load of composite plates. It is understood that the buckling load increased with regard to the increase groove angle (from 0° to 90°) of the composite plates. As the laminate designation changed, the buckling load also changed significantly. The buckling load of composite plates is highly influenced by its weave type. As a fiber, it has been determined that the buckling behaviour of carbon fiber is better than glass fiber. In addition, it was concluded that the twill weave type is generally better than the plain weave type.

Low-velocity impact behavior of interlayer hybrid foldcore sandwich structures with carbon/glass fibers

Interlayer hybrid foldcore sandwich structures have been introduced in this study. Both facesheets and foldcores were hybridized in the same ply sequence with two layers of plain woven carbon (C) and two layers of satin woven glass (G) fiber prepregs (Carbon-to-Glass ratio 1:1). Foldcore sandwich structures with six-ply combinations were designed including two symmetric layups (GCCG and CGGC) and four asymmetric layups (CGCG, GCGC, CCGG, and GGCC). The static compression and low-velocity impact performance of foldcore sandwich structures of different ply sequences were investigated. A user-defined material subroutine (VUMAT) was employed to characterize the damage evolution of composite materials based on selected failure criteria. The findings revealed that hybridization was effective in enhancing its energy absorption value of pure carbon fiber foldcore sandwich structures in terms of static compression performance. The damage degree of the interlayer hybrid foldcore sandwich structures increased gradually with the increasing impact energy. Moreover, the damage of facesheet was mainly caused by fiber tensile, matrix tensile damage and delamination, and damage of foldcore was mainly delamination. GCGC sandwich panel with asymmetrical cross-ply sequence has the optimal load bearing capacity, and CGGC sandwich panel with symmetrical layup has a strong energy absorption capacity under high-energy impact load. The foldcore sandwich structure showed smaller peak load, longer crushing distance, and more energy absorption value under larger oblique impact angle. The simulation and experimental results show good agreement in peak force, maximum energy absorption, and damage mode.