T700 Carbon Fiber Research Articles

Post-Buckling Response of Carbon/Epoxy Laminates with Delamination under Quasi-Static Compression: Experiments and Numerical Simulations.

Delamination is a common type of damage in composite laminates that can significantly affect the integrity and stability of structural components. This study investigates the post-buckling behavior of carbon fiber-reinforced epoxy composite laminates with embedded delamination under quasi-static compression. Experimental tests were conducted using an electronic universal material testing machine to measure deformation and load-bearing capacity in the post-buckling stage. The specimens, prepared from T300 carbon fiber and TDE-85 epoxy resin prepreg, were subjected to axial compressive loads with delamination simulated by embedding Teflon films. Finite element analysis (FEA) was performed using ABAQUS software, incorporating a four-part model to simulate delaminated structures, with results validated against experimental data through comprehensive convergence analysis. The findings reveal that increasing delamination depth and length decrease overall stiffness, leading to an earlier onset of buckling. Structural instability was observed to vary with the size of delamination, while the post-buckling deformation mode consistently exhibited a half-wave pattern. This research underscores the critical impact of delamination on the structural integrity and load-bearing performance of composite laminates, providing essential insights for developing more effective design strategies and reliability assessments in engineering applications.

Investigation of Titanium Nitride as an Effective Interphase for Carbon-Fiber-Reinforced Silicon Carbide Ceramic Matrix Composites.

Ceramic matrix composites (CMCs) have played a significant role in increasing the efficiency of gas turbine engines. CMCs combine the high temperature resistance of ceramics with the high mechanical strength of ceramic fibers into a single unit. Interphase layers are a crucial component in CMCs, as they prevent ceramic fibers from oxidation and introduce strengthening mechanisms into the composite. Hexagonal boron nitride and pyrolytic carbon are the most commonly used interphase layers in the aerospace industry. Other than that, very few materials have been evaluated as interphase layers. In this study, we explore the possibilities of using titanium nitride as an interphase layer in single-tow CMCs (mini composite) representative of a unidirectional composite at a smaller scale. T-300 carbon fibers were coated with TiN by atmospheric pressure chemical vapor infiltration using TiCl4, N2, and H2. The deposition temperature, precursor flow rate ratio, total precursor flow rate, and deposition time were optimized to obtain high-quality coatings. The best coating was produced at 800 °C, 4:1 H2 [TiCl4]/N2 ratio, 125 standard cubic centimeters per minute (N2 + H2 [TiCl4]) total flow precursor flow rate, and 2 h of deposition time. At these conditions, the coatings displayed good fiber coverage, good fiber adhesion, minimum fiber linkage, and minimum surface roughness. There was minimum fiber degradation after TiN coating, with a retention of 95% of the initial Young's modulus and 26% of the ultimate tensile strength of the carbon fiber. Adding the TiN interphase coating to the Cf/SiC CMC increased the ultimate tensile strength of the composite by 1122% and Young's modulus by 150%.

A systematic framework for the design and material selection of composite for tennis racket upon impact

The present study explores the comprehensive composite material selection methodology of a tennis racket involving coupled Multi-Criteria Decision-Making (MCDM) and numerical analysis. Initially all the possible material alternatives from the composite family were shortlisted using CES Selector 2016. A design space was developed incorporating MCDM technique naming VICKOR (VIseKriterijumska Optimizacija I Kompromisno Resenje), PROMETHEE (Preference Ranking Organisation Method for Enrichment Evaluation) and TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) to rank the most suitable composite material based on critical mechanical properties to identify the most suitable composite materials for applications requiring optimal combinations of rigidity, strength, and structural performance. Using finite element analysis, the structural integrity of each of the materials was evaluated on static and dynamic stress analysis modules of ANSYS. Out of all material alternatives, T300 carbon fiber epoxy was considered as the most suitable for tennis rackets. Further, a comparison between the selected material was also made with conventional materials and were found in good agreement with selected material.

Preparation and mechanical properties of the 2.5D carbon glass hybrid woven composite materials

Abstract The 2.5D carbon glass hybrid woven composite (CGHWC) is currently being utilized as a protective material for the external cables of solid rockets due to its extensive advantages in terms of structural load-bearing and integrated thermal insulation. This study reveals that 2.5D hybrid woven composites, prepared using T300 and T800, exhibit improved compression and tensile properties, respectively. T300 and T800 carbon fibers are preferred for the preparation of 2.5D CGHWC, with a volume fraction of carbon fibers along the weft yarn ranging from 20 to 60%. As the proportion of carbon fibers increases, the weft tensile and compressive strength of the composite material progressively improve, resulting in a maximum increase of 67% in tensile strength and 52% in compressive strength. The optimal volume fraction of carbon fibers was found to be 40%. The performance retention of low-cost hybrid composite materials was investigated, and it was found that even when the cost of carbon fibers decreased by 87.5%, the mechanical properties could still be maintained at above 85%. This article has expanded the mechanical performance database of hybrid composite materials, providing data support and theoretical foundation for the large-scale engineering application of composite materials.

Effect of temperature on flexural and interlaminar shear strength properties of carbon‐epoxy composites: Experiment and modeling

AbstractCarbon fiber composites are known for excellent specific mechanical properties at room temperature. It is important to model the effect of temperature on flexural strength and interlaminar shear strength (ILSS). In this study, T700 carbon fiber composites with two different epoxy resins (Epofine, LY556) were prepared using filament winding and named as TE and TL composites. The dynamic mechanical analysis (DMA) tests revealed Tg of 177 and 192°C for TE and TL composites, respectively. Three‐point bending (flexural) and short‐beam shear (ILSS) tests were performed at −20, 0, RT, 90, 105, 150, 170, and 200°C. It was observed that flexural strength and ILSS decreases linearly with increase in temperature. Fracture analysis of flexural samples revealed fiber breakage at −20°C and micro‐buckling at elevated temperature are dominant failure mechanisms. Fracture analysis of ILSS samples showed delamination with microcracking at −20°C and plastic deformation of matrix at elevated temperature. A new empirical model was proposed to predict the temperature dependent flexural strength and ILSS. With this model, variation of flexure strength and ILSS with temperature can be estimated from respective values at RT, Tg and storage modulus values from DMA, thus extensive experimentation at high temperatures can be avoided.Highlights Mechanical properties of filament wound composites are tested from −20 to 200°C. Flexural strength and ILSS linearly decreases with increase in temperature. Fiber breakage at −20°C and micro bucking at 200°C are dominant in flexure. Delamination at −20°C and plastic deformation at 200°C are dominant in ILSS. Analytical model for finding temperature dependent flexural strength and ILSS.

Quasi-static and fatigue crack growth simulation in co-consolidated thermoplastic joints containing crack arrest features

In the present article, quasi-static and fatigue crack growth in co-consolidated thermoplastic Crack-Lap Shear (CLS) specimens containing two different Crack Arrest Features (CAFs) have been numerically simulated. The substrates have been manufactured from unidirectional T700 carbon fiber reinforced Low-Melt PAEK thermoplastic material. The Friction Stir Spot Welding (RFSSW) and the Induction Low Stir Friction Riveting (ILSFSR) CAFs were studied. Crack growth simulation has been based on the cohesive zone modeling method and has been implemented via the LS-Dyna FE software. Both static and fatigue crack growth models have been successfully validated against results from respective mechanical tests. Both CAFs have been proven capable of delaying crack growth, especially for fatigue loading. An evaluation of various installation parameters of the two features, such as the diameter, the distance to the crack tip, and the installation depth, was performed for the quasi-static loading cases. All parameters have been found to affect the crack stopping efficiency, but the most important effect comes from the diameter of the CAF. Furthermore, a series of quasi-static and fatigue simulations have been run on a mono-stiffener element, representative of an aeronautical structural assembly, in order to evaluate numerically the efficiency of the CAFs at a higher scale. The results showed no crack stopping for the ILSFSR and a low crack stopping for the RFSSW for fatigue loading.

High‐performance poly(methylsilane arylether arylacetylene) resins with low curing temperatures and weak secondary relaxations

AbstractA series of poly(methylsilane arylether arylacetylene) (PSEA‐H) resins were synthesized from methyldichlorosilane and isomeric arylether arylacetylenes, and characterized by 1H‐NMR and FT‐IR spectroscopies. The effect of reactive Si‐H groups and the linking positions of benzene rings in the arylether arylacetylene units on the properties of the resins were investigated. The results show that PSEA‐H resins possess good processability with processing windows of over 80°C. The introduction of Si‐H groups reduces the curing temperatures for PSEA‐H resins and weakens the secondary relaxation for the cured PSEA‐H resins. The cured resins and T300 carbon fiber (T300CF) reinforced composites display high mechanical properties. The flexural strengths of a cured PSEA‐H resin and its T300CF composite at room temperature reach 64.2 and 426.5 MPa, respectively. The flexural properties depend on the linking positions of benzene rings. The cured PSEA‐H resins show excellent heat resistance with a temperature of 5% weight loss (Td5) above 500°C.

Integrated composite electrothermal de-icing system based on ultra-thin flexible heating film

Icing is a serious threat to the flight safety of aircraft. Lightweight and efficient electrothermal de-icing systems for carbon fiber reinforced polymer components are expected to contribute to the lightweighting and electrification of aircraft. This study presents the development and test of a novel, integrated, multifunctional composite electrothermal ice protection system. The system achieves this by incorporating a carbon-based ultra-thin flexible heating film into a carbon fiber-reinforced polymer composite laminate. T700 and M40 carbon fiber prepregs were used. The system composition and configuration were designed based on the anisotropic mechanical and thermal properties of the carbon fiber-reinforced polymer composite. The effects of ply stacking sequence, presence of insulation layer, ply angle, heating area, and prepreg type on thermal response and de-icing performance were investigated. Thermal response experiments were carried out in both room temperature and low temperature environments. A one-dimensional thermal response analysis model was developed for a representative heating structure. Comparative de-icing experiments were conducted on different samples in a low-temperature test chamber. A numerical model, based on the modified enthalpy-porosity method, was developed to simulate the de-icing process, and showed good agreement with the experimental results. Experiments and numerical calculations show that the arrangement of the heater close to the deicing surface improves the performance of the electrothermal deicing system while maintaining the overall mechanical properties of the multi-layer structure. While the insulation layer helps marginally with heat loss during de-icing, it significantly increases the system’s thermal inertia, which delays the de-icing’s start. It is recommended to minimize or eliminate insulation layer thickness. Rapid de-icing effects, combined with energy conservation, can be achieved through a short-term, high-power heating strategy.

Hydrothermal aging behavior and effects on carbon fabric/polyphenylene sulfide composite

AbstractCarbon fabric/polyphenylene sulfide (CF/PPS) composite has been used in the aircraft industry, which might suffer moisture and high temperature in service, leading to degradation and even failure. Therefore, knowledge of hydrothermal aging behavior and effects is needed to ensure service life. This work explores the water diffusion behavior, crystallization, and interfacial properties of CF/PPS composite under hydrothermal aging in continuous 3 months and periodical cycles. Diffusion coefficients were calculated through the Fickian model, crystallization behaviors were measured through differential scanning calorimetry and polarized optical microscope, and interfacial properties were characterized by interfacial shear strength, and interlaminar shear strength. The results demonstrate the crystal morphology transforms from transverse crystals to spherulites at the CF/PPS interface after recrystallization through hydrothermal aging, revealing water has a significant impact on the nucleation performance of T300 carbon fiber in the PPS matrix. Hydrothermal aging affects the crystallinity and crystal morphology of CF/PPS composite after recrystallization, and impacts the micro and macro interfacial properties.Highlights Transverse crystals transform to spherulites at CF/PPS interface after water uptake. Water impacts on nucleation performance of T300 carbon fiber in PPS matrix. Hydrothermal aging effect can be accumulated and promotes water uptake. ILSS drop is related to water uptake content, crystallization and IFSS changes.

Study on the mechanical properties of C/C composites reinforced by different types of carbon fibers

With the aim of selecting suitable carbon fibers as reinforcement material for carbon/carbon composites, needled carbon fiber felt preforms are fabricated by T300 carbon fibers and TZ300 carbon fibers as raw material respectively. The industrial CT results of prepared deposited carbon/carbon (C/C) composites show that the porosity of the composites fabricated by T300 is higher than that of TZ300. The mechanical properties of C/C composites after deposition and heat treatment are comparatively investigated. The results show that the difference between two deposited composites is small, while the difference at high temperature is large. After 2100 °C and 2450 °C heat treatment, the mechanical properties of T300-C/C composites show a gradual decline, while the TZ300-C/C composites decrease sharply, indicating that the high-temperature properties of TZ300 carbon fiber is inferior to T300 carbon fiber. The fracture mechanisms of two composites are investigated through microscopic fracture observation. T300 carbon fibers are still attached to the pyrolysis carbon layer while TZ300 fibers are completely stripped from the fracture surface. The interfacial bonding between T300 and pyrolytic carbon is higher than that of TZ300.

In-plane thermal expansion behavior of M55J carbon fiber reinforced SiC matrix composite

With the rapid development of high-precision ultra-stable spacecraft, the absolute values of coefficients of thermal expansion (CTE) of carbon fiber reinforced SiC matrix composite (C/SiC) are required to be closer to 10−7 K−1 or even lower. In this work, high-modulus and low-expansion M55J carbon fiber was selected to replace T300 carbon fiber as the reinforcement to decrease the CTE of C/SiC. The interfacial region, pore distribution and microstructure evolution during the densification process were investigated. With the replacement of T300 carbon fiber by M55J carbon fiber as the reinforcement, axial thermal residual stress in SiC matrix can increase to 378 ± 26 MPa, resulting in the generation of matrix microcracks. This can reduce the constraint of matrix to carbon fiber and provide expansion space for M55J-C/SiC. Therefore, the average in-plane technical CTE of C/SiC in the range of −20 to 50 °C can be reduced from 1.09 × 10−6 to 0.34 × 10−6 K−1.

A method of obtaining the anisotropic complex moduli of carbon fibers by fitting

AbstractA novel fitting method of obtaining the anisotropic complex moduli of fibers based on the complex moduli of matrix and composites is presented. The complex longitudinal, transverse and in‐plane shear moduli of the unidirectional T700 carbon fiber reinforced epoxy resin composite and the complex modulus of its matrix are measured using dynamic mechanical analysis. The predicted properties of the composite are calculated using the generalized method of cells (GMC). The complex axial, transverse and axial shear moduli of the carbon fibers are obtained by minimizing the sum of the squares of the modules of the difference between the test properties and predicted properties. Finally, the results of the experiment, finite element analysis, and GMC are compared. The results show that the complex axial and transverse moduli of the carbon fibers can be accurately evaluated, while the complex axial shear modulus cannot be accurately determined.

Fatigue behavior of Al-CFRP spot-welded joints prepared by electromagnetic pulse welding

In this study, the fatigue performance of magnetic pulse welding (MPW) joints of AA5052 aluminum alloy and T300 carbon fiber reinforced polymer (CFRP) with sandwich structure was systematically investigated. Mechanical property tests and microscopic observations were used to evaluate joint performance and damage to the CFRP. The results showed that satisfactory tensile strength (up to 92.24% of the tensile strength of the base material) was obtained by optimization of discharge energy. However, the samples in the fatigue test exhibited more sensitive properties to the fatigue environment. The higher fatigue cycle life was demonstrated only when the stress amplitude Sa ≤ 20.41 MPa. The fatigue test data were analyzed by Weibull distribution to fit the S-N curves under different reliability levels, which can be used for reliability assessment and life prediction in practical applications. The CFRP surfaces in different states were studied by scanning electron microscope (SEM). It was found that MPW would not damage the surfaces, while delamination and cracking would gradually occur during the fatigue process.

Study on Evolution of Surface Morphology and Temperature of Carbon Fiber Composites Irradiated by Millisecond Pulsed Laser

The study of the interaction between laser and composite materials has attracted the attention of many researchers. In this paper, the surface morphology and temperature evolution of T300 carbon fiber composites irradiated by millisecond pulse laser were studied and analyzed experimentally. The transient morphology change process of the front surface of the material was observed by a camera. With the injection of pulsed laser energy, the material began to change its characteristics from the center, leading to a decrease in reflectivity of it, and this area expanded with the accumulation of laser energy. The temperature change on the back of the material was observed by a thermal imager. Within a certain range and the same laser irradiation time, the greater the injected energy per unit area, the faster the temperature of the back center rises. However, under the same circumstances as above, the highest center temperature of the back of the composites is only related to the total energy injected, and has nothing to do with the spot size.

THE INFLUENCE OF HIGH-MODULUS CARBON FIBER ON THE STRUCTURE OF POLYETHER ETHER KETONE

Nowadays, polymer-based carbon-plastics confidently displace common tribotechnical and structural materials (steel, aluminum, titanium, etc.) in the automotive, metallurgical, and agricultural industries. It happens due of the fact that carbon-plastics surpass steel and aluminum 5 and 7 times, respectively in terms of strength, and they are also characterized by low weight and ease of processing. An equally important factor is the possibility of manufacturing parts of various geometric shapes in one molding cycle, which also affects the attractiveness of using carbon plastics. In addition, products made of carbon plastics are characterized by low coefficients of friction and thermal linear expansion, high resistance to fatigue damage, mechanical shocks, solar radiation, corrosion, moisture, and high temperatures, while simultaneously reducing energy consumption during production 3—20 times. All the listed advantages of carbon plastics result from the interaction between the filler and the polymer matrix, which leads to a change in the structure of the materials. That is why studying this interaction and structure as a whole is an important step in the development of new materials. It is known from literary sources that its structure has a significant influence on the functional properties of a polymer composite: an increase in the degree of crystallinity leads to an increase in the strength, rigidity, and heat resistance of the polymer material. Considering the above, the purpose of the work was to study the influence of carbon fiber on the degree of crystallinity of polyether ether ketone. The article presents the results of X-ray analysis of carbon plastics based on Victrex150 G polyether ether ketone. The impact of compression moulding on the structure of composites is analyzed. It is shown that the carbon fiber structure is organized due to consolidation, while the processing of tableted samples into products by the method of compression moulding. The dependence of the crystallinity of carbon plastics on the content of Toray T700 carbon fiber is given. The expediency of conducting additional tests is shown to establish the influence of technological factors of compression moulding (temperature, load, exposure), as well as fiber length on the radiographic structure of the designed composite

A rapid technique for detecting and localizing damage in composite laminates

Composite materials are prone to impact damage, which affects structural stability and causes safety concerns. Due to the complexity and diversity of them, the damage localization in composite materials is very challenging and is getting more attention in the research community. This paper presents a rapid technique for composite damage localization without any prior knowledge of direction-dependent velocity profile. The proposed solution technique uses the time difference of arrival (TDOA) of Lamb waves. The TDOA is obtained by the cross-correlation technique applied to the received signals at different sensor pairs in two “L” shaped sensor clusters (LSSCs). With the help of the LSSC, only seven sensors are required to quickly predict the delamination damage location for quasi-isotropic and anisotropic composite materials (QACM). A simulation model was established to study the influence of damage location and different layup directions on the localization results. The experimental verification was carried out on a T300 carbon fiber board. The localization results of simulation and experiment showed good matching, which proves that the technique is suitable for QACM.

Analysis of electron emission characteristics of triggered vacuum switch based on cold cathode materials

A trigger vacuum switch that works for a long time is subject to the stable emission of initial electrons. Cold cathode materials such as velvet and carbon fiber have the characteristics of large emission electron area, uniformity, and stability. In this paper, two cold cathode materials, namely T4 rayon velvet and T300 carbon fiber board, are attached. They were used on the surface of the vacuum switch cathode, the trigger electrode was located in the middle of the cathode, and the trigger vacuum switch was triggered by a positive polarity high-voltage pulse along the surface flashover. The breakdown voltage and dispersion were studied in the form of capacitive discharge, and the electron emission characteristics of the two materials were explored from a microscopic perspective, such as through scanning electron microscope and energy dispersive spectrometer element analysis. The results show that the triggering vacuum switch using this cold cathode material has stable triggering, wide operating voltage, and low breakdown voltage dispersion. The electron emission of the velvet has both fiber tip emission and lateral flashover mechanism, and carbon fiber is prone to surface damage; the anode metal surface is partially carbonized due to electron sputtering.

Evaluation interfacial properties of resin with bond exchange reaction / T700 carbon fiber by micro-drop test and FEM

Vitrimer epoxy resin is a newly developed resin with bond exchange reaction, which has potential applications in the field of recyclable fiber composites. The force-displacement curve of T700 carbon fiber monofilament pulled out from Vitrimer epoxy microdroplet was obtained by the microdrop test, and the interfacial shear strength of the composite system was obtained. Based on the cohesive contact theory, the finite element model (FEM) of the micro-drop test was set up. The calculated force-displacement curve is consistent with experimental data. The fracture strength and parameter characterization of the interface between Vitrimer epoxy and carbon fiber composites are further discussed.

Preparation and ablative behaviors of carbon fiber‐reinforced polydimethylsiloxane‐ co ‐poly(silylene acetylenearyleneacetylene) composites

Two block copolymers with poly(silylene acetylenearyleneacetylene) (PSA) as block A and polydimethylsiloxane (PDMS) as block B have been synthesized by Grignard reagent. The structure and properties of the copolymers have been studied. The chopped T700 carbon fibers have been used to reinforce the copolymers to obtain the composites. The ablation and change of composition on the surface of composites have been further investigated. The results show that there are two block structures of ethynyl-endcapped copolymers. The copolymer with ABA structure (PPSOA-1) is solid at room temperature, and the other with BAB structure (PPSOA-2) is viscous. The thermal stability of the cured PPSOA-1 is higher than that of the cured PPSOA-2. The chopped T700 carbon fibers reinforced copolymer composites keep shape well after 300 s at 600°C in a muffle furnace and maintain above 91% weight retention. Under the heat flow of 1 MW m−2, there are white inorganic layers on the surface of the composites after ablation in 120 s at 1200°C. The white layer on the T700CF reinforced PPSOA-1 composite is hollow and composed of amorphous carbon-containing silica. The block copolymer of PDMS-co-PSA with excellent thermal stability is promising for utilization in thermal protection systems.

A method of obtaining anisotropic loss factors of carbon fibers by indirect fitting

AbstractA fitting method is proposed to estimate the anisotropic loss factors of the T700 carbon fibers. In this fitting method, the loss factors of fibers are taken as unknown variables, storage modulus of fibers is assumed to be invariant. The generalized method of cells (GMC) is combined with the correspondence principle to calculate the loss factors of unidirectional carbon fiber reinforced plastics, and the loss factors of fibers are obtained by fitting the loss factors of composite material with the least square method. The loss factors of the T700 carbon fibers obtained by the fitting method are compared with the experiment and verified by the finite element method based on the direct‐solution steady‐state dynamic analysis and the representative volume element. Results show that the fitting method based on the GMC can accurately calculate the anisotropic loss factors of the T700 carbon fibers.