Carbon Fiber Reinforced Resin Matrix Research Articles

A novel pultrusion method and axial compression behavior of 3-D braiding-winding-pultrusion composite tubes at different temperatures

The 3-D carbon fiber reinforced resin matrix composite tubes were designed and formed via a type of novel braiding-winding-pultrusion processing technique. The effects of temperature environments (lower, normal and high temperature) on the axial compressive mechanical responses and damage behaviors of novel 3-D braiding-winding-pultrusion composite (BWPC) tubes were investigated. It was found that the BWPC tubes combined with three forming process features has a complex compression failure mode. The CT image was show that the fiber damage methods of braiding, winding and pultrusion layer were different, and the structural design of the tubes directly affects the axial bearing capacity. The axial quasi-static compression failures of tubes were the flowering failure of petals at one end. The fiber fracture and fiber block falling off was more apparent when under the lower temperature environment. The research also indicated that, when the temperature exceeds 180 °C, the resin softening and stratification will be destroyed.

Buckling of helically wound composite cylinders under uniform external pressure

ABSTRACT This study investigated the buckling behaviours of helically wound composite cylinders subjected to uniform external pressure. Three composite cylinders with lengths 180, 280, and 380 mm were manufactured through ±55° winding. Cylinders with a wall thickness of 3.12 mm and inner radius of 103 mm were constructed from carbon fibre reinforced resin matrix composites. Externally hydrostatic tests were conducted to determine the collapse strength and postcollapse modes of the three cylinders. Furthermore, the analytical, linear eigenvalue, and Riks methods were used to study their buckling behaviours. The experimental, analytical, and numerical data agreed well with each other. The Riks method considers Hashin damage initiation and linear damage evolution and can therefore be used to reasonably estimate the postcollapse modes of cylinders.

Study on the aging properties of 3D woven composites under corrosive conditions

Different aging conditions have an important influence on the performance of carbon fiber composites. In this study, the properties of three-dimensional woven carbon fiber reinforced resin matrix composites were investigated and analyzed in three different aging environments (distilled water immersion, 30% H2SO4 solution immersion, and 10% NaOH solution immersion) at 60°C. Mass change, moisture absorption change, Fourier transform infrared spectra (FTIR), surface morphology before and after aging, glass transition temperature (Tg), compression properties, bending properties, and interlayer shear properties were analyzed. The results showed that the immersion in 10% NaOH solution made the specimens destroyed and the aging process was chemically changed. Distilled water immersion and 30% H2SO4 solution immersion moisture absorption rate to meet the FICK law, the aging process only physical changes. The surface of the composite specimens under the three aging conditions produced different degrees of cracks and different degrees of debonding at the interface between the fibers and the resin matrix. The Tg, flexural properties, interlaminar shear properties, and compressive properties of the aged specimens all showed different degrees of degradation.

Dynamic snap-through of bi-stable laminates with simply supported at four corners under impact loads

In this paper, nonlinear dynamic responses of bi-stable laminate being simply supported on four corner points, which is subjected to various impact loads, are analyzed from theoretical viewpoints. Consider a four layers asymmetric cross-ply bi-stable laminate composited by the carbon fiber reinforced resin matrix. A novel configuration function that satisfies the boundary condition is proposed to predict the equilibrium configuration. Then, employing the first order shear deformation theory, the von Kàrmàn strains and Hamilton principle, nonlinear dynamic equations of motion expressed by two curvatures are derived. To obtain the two stable configurations of the laminate, the inertia terms are ignored. With the aids of static equilibrium equation, the side length and curvature of the system are solved by using NLPSolve functions in the Maple software. The stable configurations are verified by comparing present results with those reported in available literatures. Consider the incremental load loading, the decreasing loading, the sinusoidal loading, the step loading, the triangular loading and periodic loading, the nonlinear dynamic response of the bi-stable laminate are discussed. The dynamic snap-through behavior, the intra-well oscillations and inter-wall oscillations are studied by numerical simulation in detail.

Design, preparation, and performance characterization of low temperature environment-resistant composite resin matrix in rocket fuel

Cryogenic technology is a vital part of our society, not only in our lives, but also in the field of cutting-edge technology. The research and application of cryogenic technology is involved in many important projects in many countries and even in the world, such as aviation, aerospace, energy, transportation, and medicine. With its high specific strength and high specific modulus, carbon fiber reinforced resin matrix composite materials have gradually become the key material for aerospace vehicles, with significant advantages in reducing structural weight and improving structural efficiency. However, in the ultra-low temperature environment such as liquid hydrogen and liquid oxygen, the overall structure of carbon fiber reinforced resin matrix composites is severely tested by the environment, and it is extremely important to evaluate the mechanical properties of the composites under ultra-low temperature due to the difference of their material structure and properties from those of traditional materials, and the difference of thermal expansion coefficients between the reinforcing material carbon fiber and the resin matrix in rocket fuel. In this paper, the epoxy resin-based composite system was prepared by modifying TDE-85 epoxy resin with low-viscosity cyanate resin through molecular structure design, which is suitable for ultra-low temperature environment. The surface tension and dynamic contact angle of the modified epoxy resin are better than those of the pure epoxy resin, and it can form a good infiltration with carbon fiber and the interfacial properties of the composite are excellent. Secondly, the modified epoxy resin-based composite unidirectional plate was prepared by wet winding molding process, and the low-temperature mechanical property test specimens were prepared according to the relevant test standards. The mechanical properties were tested at −196℃, −150℃, −90℃ and room temperature 25℃ to obtain the low-temperature mechanical properties of the composite system, which provided the basis for the design of the composite system in the ultra-low temperature environment. Finally, the microstructure of the epoxy matrix composites was characterized by SEM method after the different temperature tests. The material structure, morphology, and composition were characterized by field emission scanning electron microscopy (FESEM, M400 FEI) with energy dispersive X-ray spectroscopy (EDS). In this paper, TDE-85 epoxy resin was modified with low viscosity cyanate resin to produce a modified epoxy resin suitable for ultra-low temperature environment, and the process properties of the epoxy resin were characterized. The surface tension of the modified epoxy resin was 43.405 mN/m, which was significantly lower than that of the pure epoxy resin at room temperature of 48.814 mN/m. Therefore, the modified epoxy resin had better flowability and required less time to wet the fibers during the molding process, resulting in higher molding efficiency.

Numerical Investigation on the Design and Optimization of Stacking Pattern for High Flexural Performance Carbon Fiber Reinforced Resin Matrix Composites

Numerical Investigation on the Design and Optimization of Stacking Pattern for High Flexural Performance Carbon Fiber Reinforced Resin Matrix Composites

Fabrication and Formability of Continuous Carbon Fiber Reinforced Resin Matrix Composites Using Additive Manufacturing

In the current process for additive manufacturing of continuous carbon fiber reinforced resin matrix composites, the fiber and resin matrix are fed into the molten chamber, and then impregnated and compounded in the original position, and finally extruded and deposited on the substrate. It is difficult to control the ratio of fiber and resin, and to achieve good interface fusion, which results in an unsatisfactory enhancement effect. Therefore, an additive manufacturing process based on continuous carbon fiber reinforced polylactic acid composite prepreg filament was explored in this study. The effects of various process parameters on the formability of composites were studied through systematic process experiments. The results showed that the process parameters of additive manufacturing have a systematic influence on the forming quality, accuracy and efficiency, and on the mechanical properties of CFRP. Through the experimental optimization of various process parameters, a continuous and stable forming process was achieved when the nozzle aperture was 0.8 mm, the nozzle printing temperature was 240 °C, the substrate temperature was 60 °C, the wire feeding speed was 5 mm/s, the nozzle moving speed was 5 mm/s, the path bonding rate was 40%, and the printing layer thickness was 0.7 mm. Based on the optimized process parameters, direct additive manufacturing of a lightweight and high-strength composite cellular load-bearing structure could be realized. Its volume fraction of carbon fiber was approximately 7.7%, and the tensile strength was up to 224.3 MPa.

Multiscale collaborative optimization for the thermochemical and thermomechanical cure process during composite manufacture

To reconcile the contradiction between the improvement of carbon fiber reinforced resin matrix (CFRP) composite performance and the increase of manufacturing cost, this paper proposes a collaborative optimization strategy for the cure process during the composite manufacture to reduce both the process-induced defects and the process time. Considering the multiscale characteristics of the composites, the temperature gradient is calculated by the macroscale laminate model through the nonlinear heat transfer thermochemical analysis, and the residual stresses are obtained by the representative volume element (RVE) microscale model, which involves the viscoelasticity, thermal expansion and cure shrinkage of the constituents during the thermomechanical analysis. The multi-objective optimization is implemented by an interface which combines the finite element based cure process analysis with the non-dominated sorting genetic algorithm-II (NSGA-II). The results show the proposed optimization strategy can significantly reduce the maximum temperature gradient, the maximum residual stress and the process time simultaneously. Besides, the self-organizing map (SOM) obtained from the Pareto front clarifies the relationship between the design variables and the objectives.

Direct electrochemical grafting of crystalline PAEK macromolecule on carbon fiber to enhance the interfacial properties of PEEK/CF composites

Electrochemical grafting of diazonium salts have been applied to improve interfacial properties of carbon fiber and matrix resin. However, these graft modifications are still limited to general-purpose carbon fiber reinforced resin matrix composites such as epoxy. In this research, the direct grafting of Poly (aryl ether ketone) (PAEK) macromolecule on carbon fiber was achieved with mild condition. Firstly, aniline was introduced into Poly (ether ether ketone) (PEEK) as pendent group to improve solubility and amino terminated group was introduced as precursor of diazonium salt. Then the graft was conduct through diazonium salt reduction. After modification, the aniline side group could be hydrolyzed off to recover crystallinity. To further analyze the graft, single molecular-force spectroscopy was introduced to investigate the surface of carbon fiber. Impressively, the extension curve suggested the PAEK macromolecule had been attached to surface through strong interaction. Combined this with XPS data, it was believed that the graft was a success. As a result, the grafted polymer along with the polymer that physically absorbed on carbon fiber in electrolyte can cooperate to strengthen the interface. The interfacial shear strength of the grafted carbon fiber and PEEK increased from 42.27 MPa to 97.33 MPa by 130.26%. The improvement mainly originated from the covalent bonding that connected the carbon fiber and the graft coating layer as well as the great compatibility between the graft coating layer and the matrix resin. These results also demonstrated the possibility to graft high performance polymers on carbon fiber through one-step modifications.

Pore-throat structure characterization of carbon fiber reinforced resin matrix composites: Employing Micro-CT and Avizo technique.

Micro-CT technique poses significant applications in characterizing the microstructure of materials. Based on the CT three-dimensional(3D) reconstruction technology and “Avizo” 3D visualization software, the microscopic pore-throat structure of porous media can be quantitatively characterized. This paper takes the carbon fiber reinforced resin matrix composites as an example to introduce the operation process of “Avizo” in details, which mainly covers the following modules: Volume Edit, Interactive Thresholding, Fill Holes, Mask, Separate Objects and Generate Pore Network Model, then further discuss the difficult problems when the “Avizo” is employed to analyze. The microstructures of carbon fiber reinforced resin matrix composites illustrate that pores in the upper part of sample are dramatically dispersed, and mainly concentrated in the lower part of sample. The porosity of adopted cuboid is 3.6%, accordingly the numbers of pores and throats reach 268 and 7, respectively. The equivalent radius of pores seems mainly distributed in the range of 0.7–0.8μm, accounting for 28.73% of the total pore number. The surface area of pore ranges from 5 to 10μm2, accounting for 14.16% of the total pore number. The pore volume concentrates in the range of 1–20μm3, accounting for 57.46% of the total pore number. In addition, the equivalent radius of throat mainly concentrates in the range of 1–5μm, the overall length of throat is distributed in the range of 37–60μm, and the equivalent area of throat is distributed non-uniformly in the range of 5–75μm2. This work provides a basis for the further investigation of fluid migration mechanism and law in the composite materials by the numerical simulation methodology.

Effects of adhesive modulus and curing conditions on curing behavior of silicate based ceramic coatings on carbon fiber reinforced resin matrix composites

Sodium silicate based ceramic coatings were prepared on the surface of carbon fiber reinforced epoxy resin matrix composite. The coatings were obtained by curing the mixture of silicate adhesive, SiO2 or Na2SiF6 as curing agent, and YSZ and Al2O3 as filler. The effects of adhesive modulus, curing agent, curing temperature and time on curing behavior of the coatings were investigated. The results indicated that the coating obtained from 2.7 modulus of silicate adhesive was dense, cohesiveness, uniform and continuous. As curing agent, SiO2 could promote curing better than Na2SiF6, achieving complete curing of the coating. And the coating containing SiO2 as curing agent was dense, flat and well adhered to the substrate. The curing behavior of coatings was significantly affected by curing temperature and time. The coatings could be cured completely with the increase of curing temperature. The best curing result was obtained at 100 °C curing temperature. Also the experimental results showed that the characteristics of coatings were improved to a certain extent by prolonging the curing time.

Calculation and Experimental Study on Extrusion Pressure of Resin in 3D Carbon Fiber Preform

Three‐dimensional carbon fiber reinforced resin matrix composite can effectively overcome the defects of traditional composite in the interlayer strength and stiffness, and has been widely used. Herein, the threshold infiltration pressure of resin in three‐dimensional carbon fiber preform is respectively calculated as 0.170 and 0.973 MPa from the perspective of statics and dynamics. The static calculation ignores the additional pressure caused by the viscous resistance of the resin during the infiltration process, which deviated greatly from the actual value. Therefore, the dynamics calculation value is used as a reference to extrusion pressure in the experiment. The composites with extrusion pressure of 1, 2, 3, 4, and 5 MPa are prepared by vacuum infiltration hot pressing process. Through the study of the infiltration microstructure and bending fracture morphology of the composite, it is found that when the extrusion pressure is 3 MPa, the preparation effect is the best. At this time, the bending strength of the composite is 540 MPa, which is 92.86% and 71.43% higher than that at 1 and 5 MPa, respectively. It is indicated that the extrusion pressure is a key parameter in the composite preparation process and needs to be selected reasonably.

Effects of loading rates on mode I interlaminar fracture toughness of carbon/epoxy composite toughened by carbon nanotube films

Carbon fiber reinforced resin matrix composites were toughened by the continuous and randomly distributed carbon nanotubes (CNTs), which were fabricated by floating catalytic chemical vapor deposition (FCCVD) method. Toughening was achieved by deploying CNT film of different areal density as interleaves in the carbon fiber reinforced composites. Double cantilever beam (DCB) specimens were adopted in both quasi-static and dynamic fracture tests. The electromagnetic Hopkinson bar was applied to achieve pure type I fracture mode at high loading speeds of 15 m/s and 24 m/s. The effects of CNTs and loading rates on the Mode I fracture toughness of the composites are investigated. It is shown that fracture toughness approaches a maximum value of 626 J/m2 under quasi-static loading, only if a 2-layered CNT film is being applied as an interleave, which is twice that of the neat composite (without CNT interleaves). Under dynamic loading, all the specimens either with or without CNTs show increases in the fracture toughness with the increase in loading rate. Different from the results of quasi-static tests, under dynamic loading conditions, the fracture toughness increases monotonously and approaches to a maximum value of 1380 J/m2 when 40-layered CNT film was applied, which is a remarkable increase of 140% if compared with that of the neat specimen. A detailed analysis of mechanisms responsible for the ameliorating effects of CNTs interleaves is carried out. It is believed that strengthening of interfaces between carbon fibers and matrix, deformation of resin and detachment of CNTs from the matrix are the main factors responsible for this effect.

Theoretical modeling and experimental verification of co-curing carbon fiber-reinforced polymer hat-stiffened panels with silicone airbag male mandrels

For closed-hole panels such as hat-stiffened panels, it is inevitable to use mandrels during the manufacturing process. However, the uniformity of pressure transmission of the silicone rubber mandrel with the prefabricated hole is not good, the vacuum bag mandrel is easy to be broken and wrinkled, the water-soluble mandrel is high in cost, and the invar steel metal mandrel is difficult to demold. To solve these problems, this article proposed a new method for co-curing carbon fiber-reinforced resin matrix composite hat-stiffened panels by using a silicone airbag as a mandrel through autoclaves. Firstly, the thermo-force-flow multi-field coupling finite element model of co-curing carbon fiber-reinforced polymer (CFRP) hat-stiffened panels was established by using finite element software. The co-curing process of hat-stiffened panels was simulated and studied. The influence of different thickness of silicone airbag mandrels on the wall thickness and pressure of the workpiece were found to be relatively uniform in the new process. Then, the autoclave experiment was carried out to verify the correctness of the finite element model. Lastly, the interfacial bonding strength test was carried out to verify the mechanical properties of the parts. In summary, the practicability of co-curing CFRP hat-stiffened panels with silicone airbag male mandrels was proved in this article. The precision of CFRP hat-stiffened panel was efficiently promoted by this new process.

Experimental Study on Damage Characteristics of CFRPs/Aluminum Honeycomb Sandwich Structure Impacted by Ultra-High Speed Under High and Low Temperatures

With the rapid development of material science, the original aluminum alloy shield structure of spacecraft has been gradually replaced by sandwiched structure of carbon fiber reinforced resin matrix composite structure with aluminum honeycomb. In order to reveal the damage characteristics induced by debris impacting on shield structure of spacecraft and aiming at the engineering requirements that spacecraft undergo alternately high and low temperature environment during on-orbit operation, CFRPs/aluminum honeycomb core sandwich shield structure is used as the impact object. The damage characteristics of 2A12 aluminum projectile impacting on CFRPs/aluminum honeycomb sandwich structure with different aluminum honeycomb arm lengths at different impact velocities are studied by using the high and low temperature system for the target and the loading system of two-stage light gas gun. The experimental results show that the arm lengths of aluminum honeycomb have little effect on the perforation area of front and rear surfaces of CFRPs/aluminum honeycomb sandwich structure at high temperature, but the impact speed has a great effect on the perforation areas of front and rear surfaces of rear panels. The lower the impact speed is, the smaller the perforation diameter is. The deformation and ablation areas of the front and rear surfaces of the aluminum honeycomb increase with the increasing of the arm length of the aluminum honeycomb. At the same time, the physical quantities mentioned above have similar changes in low temperature environment. The fitting formulas, such as the relationships among perforations of the front and rear surfaces of CFRP and the arm lengths of aluminum honeycomb, and ablation area of aluminum honeycomb and the arm lengths of aluminum honeycomb are given at the given experimental conditions. The micro-morphology and damage characteristics of the panels and aluminum honeycomb are analyzed at the different locations near the impact point at high temperature.

Determining the interphase thickness and properties in carbon fiber reinforced fast and conventional curing epoxy matrix composites using peak force atomic force microscopy

Quantitative analyses of the thickness and properties of the interphase in carbon fiber reinforced resin matrix composites, which play an important role in loading transfer, are essential and intuitive to accurately design the properties of the composites. In this study, to know the distinctions of the interphase between the carbon fiber reinforced fast and conventional curing epoxy matrix composites quantitatively and completely, in addition to modulus map, adhesion map by Peak Force Quantitative Nano-Mechanics technology was newly introduced and applied to determine the interphase thickness and properties. The interphase in the fast curing epoxy matrix composites in modulus image was found to be soft with an average thickness of 20.03 ± 2.04 nm, while it was 40.48 ± 4.17 nm in the conventional curing epoxy matrix composites, and the modulus of the interphase formed a depression between the fiber and the matrix. Consistent with the interphase thickness determined by the modulus, the average interphase thickness in the fast and conventional curing epoxy matrix composites were 19.45 ± 0.68 nm and 41.01 ± 3.98 nm, respectively, based on the adhesion contrast in the interphase, and the adhesion of the interphase reached a peak between the fiber and the matrix. Compared with the conventional curing epoxy matrix composites, the modulus and the adhesion of the interphase changed more sharply in the fast curing epoxy matrix composites. Obviously, numerous distinctions of the interfacial properties existed between the fast and conventional curing epoxy matrix composites.

Thermal plasticity deformation buckling analysis on the carbon fiber-reinforced aluminum matrix composite material

As light weight and durability have become the important design objectives for the modern aircraft structures, the carbon fiber-reinforced resin matrix composites are widely applied to the aircraft structures for it can reduce the airframe weight effectively at the same time of guaranteeing the load-carrying capacity. In aircraft structures, the mechanical connection remains the important connection pattern for the composite material and the laminated structures; however, existence of the connecting hole has resulted in the stress concentration of structures while the borehole fatigue breakdown of parts is the main failure mode of aircraft structures. According to the low fatigue life of the aircraft connection structures, research on the hole extrusion and reinforcement technology on the carbon fiber-reinforced composite material and the laminated structure is made in this paper.

Study of the curing process of carbon fiber reinforced resin matrix composites in autoclave processing

Carbon fiber reinforced resin matrix composites (CFRP) has been widely used in aerospace due to its strong comprehensive mechanical properties and light weight. The autoclave processing is the best manufactruing methods for this material. But it still has some shortcomings, such as thermal spike in curing process, which leads to non-uniform temperature distribution, that will cause residual stress. Numerical simulation are presented to observe the curing process, such as temperature and degree of cure in the composite plate. The temperature evolution obtained in the plate is coincide with that of the experimental results. The results indicated that temperature inside of the plate increase faster than outside of the plate. thicker plate is more likely to have a thermal spike in the center of the composite plate than thin one.

Numerical simulation of stress distribution for CF/EP composites in high temperatures

The high-performance carbon fiber materials can be obtained by decomposing carbon fiber reinforced resin matrix composites using thermally activated oxide semiconductors. This paper established the representative volume element (RVE) of carbon fiber/epoxy resin composites, and investigated the structure destruction of composites in the recycling process based on analysis of the stress and strain distribution by the thermomechanical coupling module of Digimat. The results indicated that the maximum thermal stress of the epoxy resin appeared in the poor resin region, while the minimum appeared in the resin-rich region; the stress of the carbon fibers in poor resin region was greater than that in the resin-rich region; the maximum stress of composites appeared in the interface layers when the temperature ranged from 350 to 500 °C, and the maximum thermal stress was 196.9–281.3 MPa, as well as the maximum shear stress was 98.2–140.3 MPa; the maximum peeling stress perpendicular to the fiber directions was 53.7–157.3 MPa; the strain of the interface layers and carbon fibers were the smaller than that of the resin matrix, whose maximum strain ranged from 0.0622 to 0.0889. The structure destruction of the composites was caused by both the peeling stress and the interfacial shear stress in recycling.

Synthesis of Y2O3-ZrO2-SiO2 composite coatings on carbon fiber reinforced resin matrix composite by an electro-plasma process

In the present paper the Y2O3-ZrO2-SiO2 composite coating was successfully synthesized on carbon fiber reinforced resin matrix composite by an electro-plasma process. The deposition process, microstructures and oxidation resistance of the coatings with different SiO2 concentrations were systematically investigated. A relatively dense microstructure was observed for the Y2O3-ZrO2-SiO2 composite coating with the SiO2 concentration above 5g/L. The coating exhibited very good oxidation resistance at 1273K with the mass loss rate as low as ∼30wt.%, compared to 100wt.% of the substrate. The formation of the ceramic composites was discussed in detail based on the electrochemical mechanism and the deposition dynamics in order to explain the effect of the plasma discharge. We believe that the electro-plasma process will find wide applications in preparing ceramics and coatings in industries.