Carbon Composite Laminates Research Articles

A probabilistic machine learning framework for stiffness tensor estimation of carbon composite laminate

The potential uses of carbon composite material are vast, particularly in the civil, mechanical and aero-structures. Nonetheless, the practical utilization of carbon composite faces challenges due to complex experimental methods and imprecise algorithms for inverting material properties. Characterization of full set of stiffness tensor for an anisotropic material in particular orthotropic material can be considered as a complex non-linear inversion problem. The inversion process requires a robust optimization algorithm and forward models. The complexity of this inversion process impedes the practical utility in large-scale automation and in real-time structural health monitoring (SHM) application. To cater this, in this work an advanced probabilistic machine learning framework based on multi-output Gaussian process regression (moGPR) is proposed as an inversion algorithm. The inversion algorithm proposed is based on probabilistic framework that utilises the dispersion of Lamb waves as an input for optimal estimation of stiffness tensor. Experimental measurements of full wavefield data of propagating waves are conducted by scanning laser Doppler vibrometer. Further, an optimal training dataset is generated by employing a forward model based on stiffness matrix method (SMM). In the presence of measurement uncertainties, the effectiveness of the optimal prediction algorithm is showcased through a comparison between the estimated parameter and its ground truth. This comparison reveals that the proposed inversion algorithm is both efficient and robust, delivering satisfactory performance even in the presence of substantial measurement uncertainties.

Pressure resistance characterisation of vascular networks embedded in carbon composites for high energy physics applications

In state-of-the-art tracking detectors, lightweight carbon composite structures support the pixel or micro-strip sensors and provide the main thermal path between the silicon and a network of metallic or plastic pipes containing a cooling fluid. Despite the good results obtained with this design approach, the challenges associated with future high energy physics (HEP) experiments demand even lighter and more efficient technologies. In this regard, replacing the existing piping with a network of channels directly embedded in the composite laminates represents a promising solution to improve the thermal coupling, which also offers additional gains in terms of mass and thermo-elastic stability.While some research has been devoted to assessing the mechanical and thermal performance of such laminates, limited information about their resistance to internal pressure is currently available in the literature. This lack of data constitutes an important obstacle for the use of vascular networks in future HEP applications, which the present paper aims to address.Experimental methods were used to investigate the pressure resistance of channels embedded in carbon composite laminates. Modified poly (lactic) acid (PLA) preforms were embedded in carbon-fibre epoxy laminates. A post-cure vaporization technique removed the PLA, thus producing plates with longitudinal channels. Destructive tests were conducted to determine the burst pressure of the plates depending on the lay-up and the cross-section geometry of the channels. Both circular and oblong channels were evaluated, and various reinforcement techniques were explored to enhance the pressure resistance of the laminates. Micro-graphic examinations and X-ray micro-computed tomography were employed to gain a better understanding of the microstructure and the failure mechanisms of the plates.Plates with circular channels measuring 1.75 mm in diameter, embedded in [0/90/0]S laminates and reinforced with 2 mm lay length fuzzy carbon fibre over-braids, achieved burst pressures exceeding 45 MPa. This result, which is approximately an order of magnitude greater than that obtained for the equivalent non-reinforced laminates, demonstrates the enormous potential of this technology for future particle detectors.

Reinforcement of concrete beams using waste carbon-nanoclay-fiberglass laminate pieces

In the last few decades, strengthening of structures in need of repair with fiber reinforced polymer (FRP) composite materials produced with different fiber types has gained great importance. Within the scope of this experimental study, the usability of hybrid glass and carbon composite laminates produced for different purposes and later cut into waste was investigated for concrete reinforcement. Hybrid composite laminates were produced in the form of glass-carbon-glass and carbon-glass-carbon, and the effect was investigated in two different sequences in the study. In addition, there are 3 different rates of nanoclay (0.50%, 0.75% and 1.25%) in the production of composite materials, and the effect of nanoclay ratio was investigated. In the study, two different numbers of composite laminates were adhered to the concrete samples produced in 70x70x280 mm dimensions and subjected to flexural strength test. In the Carbon-Glass-Carbon series using triple waste laminate pieces, the highest flexural strength was reported in the CGC-0.75-3 series, which achieved an increase of approximately 55% and 42% compared to the Control and Control-E series. It was determined that the effectiveness of the reinforcement technique of concrete with laminates in flexure did not change significantly depending on the number of laminate pieces. The main mode of failure in the experimental work was due to concrete fracture.

Experimental characterization of unidirectional carbon – Carbon composite laminate

Advanced polymeric Composites have wide applications in various industrial sectors of Missile System, Automobile, and Space Structures have been sound prominent and endlessly receiving the wide awareness for many industries. The structural engineer desires to be eminent with the belongings of the composite material structures. The performance of fiber reinforced polymeric composite material beneath dynamic load plays a crucial task in designing such structures. In the recent work, an attempt is made to determine optimum fiber angle and the behavior of the advanced polymeric composite material, i.e., Carbon – Carbon Composites under Tensile and Compressive loads. Mechanical properties, viz., Compressive and Tensile strength are determined by using experimentation method. Hand layup technique is used for fabricating the laminates. FE Analysis (Ansys) is carried out on various fiber angles likely be [0°-90°], [30°], [45°], [60°] to validate the results which is obtained from experimentation.

A degradation-shock dependent competing failure processes based method for remaining useful life prediction of drill bit considering time-shifting sudden failure threshold

• A dependent competing failure model is established for drill lifetime estimation. • The effect of wear degradation on the sudden failure threshold is considered. • Reliability functions and useful life expression of the drill are derived. • A drilling experiment is provided for validating the proposed method. Accurate remaining useful life (RUL) prediction of the drill bit is central to ensuring the processing quality of products and enhancing processing safety and reliability. However, the majority of current methods are confined to considering the wear degradation during the drilling and ignore the combined effect of wear degradation and random shock on RUL. Therefore, it is difficult to the sudden failure prediction of the drill bit. To address this limitation, a degradation-shock dependent competing failure processes (DCFPs) based method considering time-shifting sudden failure threshold is proposed in this paper for RUL prediction. First, a degradation-shock DCFPs model is established based on the processing characteristics of the drill bit. Further, the expressions of reliability function and useful life taking into account the time-shifting sudden failure threshold are derived. Then, based on the Bayesian method, a two-step maximum likelihood estimation (MLE) is designed for parameter estimation, and the crucial parameters are updated utilizing a local gaussian importance resampling particle filter. Finally, a carbon composite laminate drilling experiment is provided for demonstration. Experimental results demonstrate the superiority of the proposed method for drill bit RUL prediction, especially when the drill bit is chipped.

Mode II- delamination modeling in multi-directional laminates using cohesive zone methodology under static and dynamic loading

Most of the ply-by-ply laminated composite structures are constrained by delamination type of failure under different loadings. There were attempts to develop modeling methods for delamination under static and dynamic loads in the past. Most of the earlier attempts are focused on the unidirectional laminates because of complexity involved in the multi-directional laminates. However, in the real life, many time multi-directional laminates are used. This paper is an effort to create such modeling methodology for multi-directional carbon composite laminates (with 0–0, 45–45 and 90–90 interfaces) under static and dynamic loads. For modeling the static load case, Ansys software is used with the in-built contact based cohesive zone material model. The mode II experiments were conducted on multi-directional carbon composite coupons as per ASTM standards and the load displacement behavior is verified using the finite element analysis (FEA) cohesive zone models (CZM). Mode II test coupons are modeled in 3D, and the delamination is captured in the analysis simulation. For dynamic loading, LS-Dyna is used with the in-built tiebreak contact-Dycoss-Option 9 capabilities which are almost similar to the cohesive zone elements. The results indicate that cohesive zone models can predict the delamination in the kind of materials under static and dynamic loading conditions. The modeling methods will be further improvised for both situations to make it more robust and ready for applications to aircraft engine components in consideration of delamination.

Drilling-Induced Damages in Hybrid Carbon and Glass Fiber-Reinforced Composite Laminate and Optimized Drilling Parameters

Hybrid carbon and glass fiber-reinforced composites have attracted significant research interest for primary load-bearing structural components in the field of aviation manufacturing owing to their low weight and high strength to weight ratio. However, the anisotropic and heterogenic nature of carbon and/or glass fiber-reinforced composite prevents high machining quality due to the directionality effect of fibers in the polymer matrix. As such, this study investigates the effect of drilling process for hybrid fiber-reinforced composite and reports optimal drilling parameters to improve the drill quality. Experimental studies indicate that an increased point angle (i.e., from 80° to 120°) resulted in low delamination upon entry due to reduced thrust force, which in turn produces better surface finish with minimal tool wear. The optimal feed rate (0.2 mm/min) ensures lower delamination at entry, since higher feed rates can increase the thrust force due to elevation in the shear area or raise the self-generated feed angle, which in turn reduces the effective clearance angle. To this end, drilling parameters were optimized using Dandelion optimizer (DO)—a cutting-edge metaheuristic search algorithm (MSA). We report the excellent consistency of DO to solve the proposed drilling optimization problem while achieving promising results as ascertained by the small standard deviation values.

Research on a defect detection method on carbon composite laminates based on digital shearography

Subject of study. Carbon composite laminates are one of the major aviation structural materials. Owing to its merits of being non-contact, self-coherent, non-destructive, and full field, digital shearing speckle pattern interferometry (DSSPI) has the potential to be effective in the detection of defects on carbon composites with various surface shapes, especially the close-type defect on composite laminates. Method. In this paper, a DSSPI system containing both simulation and experiment, used for the measurement of carbon composite laminates with different curvature radii, is established. Main results. Based on our proposed criterion to evaluate whether the defects can be judged or not, the experiment loading parameters are applied, and the detection abilities under variable loading parameters are predicted. The effectiveness of the experiment system is verified through comparison with the X-ray and the ultrasound techniques. The simulation results are consistent with the experiments, showing its effectiveness. Practical significance. The work in this paper can provide reliable guidance to the loading parameters and predict the detection performance in a real DSSPI experiment system.

A general method for determining probabilistic S-N curve based on static strength data of material

The conventional group test method for obtaining probabilistic S- N curve is a time-consuming and expensive test program. This study aims to present an alternative method for determining the probabilistic S- N curve of material based on its static strength data. Firstly, the probabilistic mapping relationship between the static strength and fatigue life of material is elaborated. Subsequently, the Weibull distribution is utilized to model the static strength and fatigue life data of material, and the correlation between the distribution parameters of them is investigated. Finally, an alternative method for determining the probabilistic S- N curve of material is proposed, and the experimental data of carbon steels and composite laminates are applied to verify its validity. The results show that the proposed method is capable of determining the probabilistic S- N curve of material based on its static strength data, which can significantly save test time and reduce test cost. In engineering applications, when the parameters of static strength distribution and the median S- N curve are known, the probabilistic S- N curve with any given survival probability can be determined through a unified analytical expression.

Research of defect detection method on carbon composite laminates based on digital shearography

Research of defect detection method on carbon composite laminates based on digital shearography

Fabrication and Mechanical Properties of PAN-based Carbon Composite Laminates for High Temperature Applications.

The main aim of this paper is an experimental investigation is to study the thermophysical and mechanical properties of polyacrylonitrile (PAN) based carbon fiber fabric and phenolic resin composites (Cf-PR) for thermal protection system (TPS) for high temperature applications. Composite laminates of Cf-PR were prepared by hand-layup method by considering the curing temperature of 1500 C at 100 kg/cm2 for 4hrs under hydraulic hot press machine. The mechanical properties of the materials such as the interlaminar shear stress (ILSS), flexural strength, compression strength, bar coal hardness, thermal property such as thermal conductivity and physical property such as density were studied. It was shown that the thermophysical and mechanical properties are responsibility for the higher strength and higher temperature applications for TPS.

Investigations of low-velocity impact behaviour of single-lap joints having dissimilar hybrid composite adherends through cohesive zone model approach

The low-velocity impact behavior of single-lap joints was investigated in this study. In single-lap joints, woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) laminates as well as a hybrid composite laminate (HCGFRE), which is formed by stacking carbon and glass composite laminates, are used as adherends. Araldite 2011 and Araldite 138 M/HV998 epoxy adhesives were used with different mechanical properties for joining similar and dissimilar composite adherends. Low-velocity impact tests were carried out with 40 J impact energy. Reaction force-time and impact energy-time graphs were obtained from the experimental study as impact response. In numerical analyses, the damage approach of composite adherend was modeled using composite stress-based failure model (Mat 59) and adhesives were modeled utilizing a mixed-mode cohesive zone model (Mat 138) that existed in LS-DYNA explicit finite element software. It was seen that the numerical results indicated a similar tendency with the experimental results due to the modeling of the adhesives using the proper cohesive zone model, the application of correct boundary conditions, and the selection of the correct contact type.

Micromechanical investigation of cross-ply carbon composite laminates with glass microtubes using CZM and XFEM

Transverse cracking and delamination are two of the most common failure modes in cross-ply composite laminates. The initiation and combination of these two failure mechanisms lead to catastrophic failure modes in composite structures. This paper investigates the impact of the layer thickness and the presence of microtubes on the in situ strength of the 90° layer, the influence of induced delamination on the strength of [0/90 n /0] laminates in micro and macro scales is also investigated. In order to model the fiber–matrix debonding and matrix cracking formation in 90° plies, the cohesive zone model and extended finite element method (XFEM) are used. Afterward, to examine the induced delamination formation which originates from the tips of the transverse cracks, cohesive surfaces are placed between adjacent layers. It was shown that by increasing the thickness of a 90° layer, both the strength of the first transverse crack formation and the stress for delamination initiation decrease. On the other hand, the presence of microtubes in the vicinity of the 90° and 0° interfaces leads to an increase in the strength of the 90° ply and postpones delamination initiation.

Heating mechanisms in induction welding of thermoplastic composites

The heat generated within thermoplastic carbon composite laminates during induction welding can be attributed to one, or a combination of the three heating mechanisms discussed in the literature: (i) Joule heating of fibers; (ii) Joule and/or dielectric heating of polymer; and (iii) fiber-to-fiber contact resistance heating. The answer to the question, which of the three heating mechanisms is most dominant, remains open. This research aims to provide an answer to this question through finite element simulations using both an in-house developed numerical Whitney-elements based toolbox for induction welding simulations (WelDone), and the commercially available software, ANSYS Maxwell. The simulations are done at two levels; first, using WelDone laminate-level simulations are performed to see in which direction: fiber-, transverse to the fiber-, or thickness direction, most of the heat was generated; and second, ANSYS Maxwell was used to simulate the solid loss on a microscopic, inside fiber and resin, level with and without the presence of resin. In the latter series of simulations, contact between fibers in different layers was explicitly modeled. The numerical simulations revealed that on the laminate-level most heat is generated in the fiber- and thickness directions. The former coincides with Joule heating of fibers, while the latter can be attributed to either Joule heating of polymer and fiber-to-fiber contact resistance heating, or both. The fiber level simulations, however, revealed that both fiber-to-fiber contact and no-fiber-to-fiber contact conditions have a significantly small effect on the solid loss compared to presence of resin. Based on the latter, the heat generation in the thickness direction was attributed to a second heating mechanism; Joule heating of polymer. It must be noted that the dielectric heating of polymer was ignored due to the relatively low operating frequency at which induction welding takes place.

Ballistic Impact and Virtual Testing of Woven FRP Laminates

The aim of the work was to investigate the numerical simulations correlation with the experimental behaviour of steel ball high velocity impact onto a 2 × 2 twill woven carbon composite laminate. The experimental set up consisted of a pressurised gas-gun able to shot steel ball projectiles onto two different composite plate layup configurations of plates made of the same composite material fabric. Subsequently, the experiments were replicated using the LSDYNA explicit finite element analysis software package. Progressive failure numerical models of two different fidelity levels were constructed. The higher fidelity model was simulating each of the plys of the composite panels separately, tied together using cohesive zone modelling properties. The lower fidelity model consisted of a single layer plate with artificial integration points for each ply. The simulation results came out to be in satisfactory agreement with the experimental ones. While the delamination extent was moderately under predicted by the higher fidelity model, the general behaviour was complying with the experimental results. The lower fidelity model was consistent in representing the damage of the panel during the impact and better predicted the impactor residual velocities due to the better matching of the pane stiffness. Despite the competency of the higher fidelity model to capture the damage of the laminate in a more detailed level, the computational cost was 80% higher than the lower fidelity case, which rendered that model impractical against the lower fidelity one, to use in larger models representing more substantial or more complex structures.

An Experimental and Numerical Determination on Low-Velocity Impact Response of Hybrid Composite Laminate

In this study, experimental and numerical investigations were carried out in order to determine the mechanical properties and impact response of hybrid composite laminate. The hybrid composite laminate was formed from plain woven carbon fiber reinforced epoxy (CFRE) and plain woven glass fiber reinforced epoxy (GFRE) fiber using VARTM (vacuum-assisted resin transfer molding) process. The mechanical properties of the hybrid composites were determined using tensile test device with a 1 mm/min loading rate at room temperature. In addition, hybrid composites were subjected to low-velocity impact test under different impact energy levels (10, 20, 30, 40 J) for determining the impact response. Moreover, mechanical properties and impact responses of CFRE and GFRE laminates were also determined to compare to those of hybrid composite (HCGFRE). Microstructure analysis was performed to investigate the damage surfaces of the fiber and matrix in the composite material subjected to impact and tensile forces. In numerical analyses, composite damage model (Mat 54) was utilized in LS-DYNA® explicit finite element program to simulate the impact behavior of CFRE, GFRE and HCGFRE laminates. Consequently, the tensile test results showed that hybrid composite laminate behaved more ductile than carbon composite laminate and it exhibited more brittle behavior than glass composite laminate. Also, it was determined that absorbed energy and impact load capacity of HCGFRE composite laminate are between absorbed energy and impact load capacity of CFRE and GFRE composite laminate. It was determined that numerical results indicate a similar tendency with the experimental results.

The Effect of Layer Thicknesses in Hybrid Titanium-Carbon Laminates on Low-Velocity Impact Response.

The purpose of the work was the effect of metal volume fraction of fiber metal laminates on damage after dynamic loads based upon the example of innovative hybrid titanium–carbon composite laminates. The subject of the study was metal–fiber hybrid titanium–carbon composite laminates. Four types of hybrid titanium–carbon laminates were designed with various metal volume fraction coefficient but constant thickness. Based on the results, it can be stated that changes in the metal volume fraction coefficient in the range of 0.375–0.6 in constant thickness titanium–carbon composite laminates do not significantly affect their resistance to impacts in the energy range of 5–45 J. It was concluded that there were no significant differences in maximum force values, total contact time, and damage range. Some tendency towards a reduction in the energy accumulation capacity was observed with an increase in thickness of the metal part in relation to the total thickness of the laminate, especially in the lower impact energy range. This can result in the lower bending stiffness of laminates with lower metal content and potential elastic strain of the composite part before the initiation of the fiber damage process.

Effect of fiber layout on signal analyzing of carbon/glass/epoxy hybrid composite laminates flexural loading using acoustic emission

In this study, Glass, Carbon and Epoxy Hybrid Composite laminates were loaded under flexural loading and monitored by an acoustical sensor and therefore, the effect of fiber layout in hybrid composite laminates on acoustical signal processing was studied. In fact, in order to diagnosis full frequency areas of the emitted signals and determining fracture mechanisms, also to obtain maximum load frequency and time; signal processing is necessary. Wavelet and Choi–Williams transforms, two analytical methods, were used to investigate the acoustic signal. Based on the results, Choi–Williams Analysis maximum frequencies have 0, 5%, −5% and −4% variation in compare with Wavelet Analysis maximum frequencies in Specimens A, B, C, and D respectively.Adding Nanoparticles to the polymer matrix composites increases inter-laminar adherence, and the possibility of delamination occurrence decreases considerably. Also, Wavelet coefficients are 4.5, 33.3, 6.3 and 18.75 times less than Choi–Williams coefficients in Specimens A, B, C, and D respectively. For more detailed studies, SEM images have been prepared.

Thermal analysis of carbon composites subjected to various atmospheric conditions

Carbon Fiber Reinforced Polymers (CFRP) are extremely strong and light fiber-reinforced polymers which contain carbon fibers. They are commonly used wherever high strength-to-weight ratio and rigidity are required. These found applications in manufacturing of aerospace, automotive, civil engineering, and sports goods components. They also offered resistant to corrosion. This research work has been carried out to investigate carbon composite tensile strengths subjected different water temperatures for a period of time. The carbon composite laminates are fabricated with 0o-90o orientation carbon fibers bonded with epoxy adhesive. A tensile test is conducted on all laminates and analyzed to find the behavior of the composite soaked to water temperatures 270, 35o, 55o, and 65o for a time period of 15, 30, 45 and 60 days.

The temperature effects on the fracture toughness of carbon fiber/RTM-6 laminates processed by VARTM

The increasing use of composite in the aircraft industry has raised the interest for a better understanding of the failure process in these materials, which can be also influenced by the manufacturing process of the laminate. Some materials used in vacuum assisted resin transfer molding process have been studied in the open literature but very few data have been published for resin transfer molding-6 epoxy based laminates, in particular studies showing the influence of the temperature on the interlaminar fracture behavior of this type of laminates. The aim of this article is to investigate the interlaminar fracture behavior of resin transfer molding-6 based carbon composite laminates manufactured by vacuum assisted resin transfer molding subjected to Modes I and II at 25℃ and 80℃. The results show the influence of the temperature on the interlaminar fracture toughness of composites and provide a database to design composite aerostructures subjected to temperatures commonly experienced in civil aviation. The fracture aspects of the tested laminates were also investigated and directly related to the trend in results found for the fracture toughness values.