Carbon Fiber Reinforced Epoxy Composites Research Articles

Environmentally friendly water-soluble epoxy emulsions nano sphere improved the interfacial performance of high modulus carbon fiber reinforced epoxy composites based on robust van der Waals force

High modulus carbon fibers (CFs) are widely desirable in aerospace, robotics, etc. However, their high degree of graphite microcrystalline structure leads to poor interfacial properties with host matrices, deteriorating the mechanical properties of carbon fiber reinforced polymer composites (CFRPs). Here, to improve interfacial properties of CFRPs, we present to construct a uniform and continuous active sizing nanolayer on the surface of CFs via synthetic water-based epoxy (WEP) emulsion nanospheres with strong van der Waals force. The WEP emulsions were prepared by introducing polar polyethylene glycols into epoxy resin chain. The modified CFRPs showed robust interfacial properties, improving by 25% over the untreated counterparts. Moreover, the proposed method can retain monofilament tensile strength of fibers and protect CFs from being destroyed during processing at industrial scales. This work opens an avenue toward the development of materials with superior interfacial performance for various inert high modulus fibers.

Effect of Thermal Exposure on Residual Properties of Wet Layup Carbon Fiber Reinforced Epoxy Composites.

Ambient cured wet layup carbon fiber reinforced epoxy composites used extensively in the rehabilitation of infrastructure and in structural components can be exposed to elevated temperature regimes for extended periods of time of hours to a few days due to thermal excursions. These may be severe enough to cause a significant temperature rise without deep charring as through fires at a small distance and even high-temperature industrial processes. In such cases, it is critical to have information related to the post-event residual mechanical properties and damage states. In this paper, composites are subjected to a range of elevated temperatures up to 260 °C over periods of time up to 72 h. Exposure to elevated temperature regimes is noted to result in a competition between the mechanisms of post-cure that can increase the levels of mechanical characteristics, and the deterioration of the resin and the bond between the fibers and resin that can reduce them. Mechanical tests indicate that tensile and short beam shear properties are not affected negatively until the highest temperatures of exposure considered in this investigation. In contrast, all elevated temperature conditions cause deterioration in resin-dominated characteristics such as shear and flexure, emphasizing the weakness of this mode in layered composites formed from unidirectional fabric architectures due to resin deterioration. Transitions in failure modes are correlated through microscopy to damage progression both at the level of fiber-matrix interface integrity and through the bulk resin, especially at the inter-layer level. The changes in glass transition temperature determined through differential scanning calorimetry can be related to thresholds that indicate changes in the mechanisms of damage.

Weibull reliability plots to study the strain rate effect on interfacial strengths of carbon fiber reinforced epoxy composites

AbstractTwo‐parameter Weibull reliability plots are utilized to determine the effects of strain rate on the interfacial strengths of unidirectional carbon fiber reinforced epoxy (CFRE) composites. Laminate specimens with two different fiber orientations are tested to failure under flexural loading. Type 1 laminates with fibers running parallel to specimen length (fiber orientation of 0° with respect to specimen span length) enable measuring inter‐laminar shear strength (ILSS) of the interface (between adjacent lamina) with locus of failure along beam mid ply. Seventy‐two type 1 laminates are tested at five levels of flexural strain rates: 1.89 * 10−5 to 9.37 * 10−2 s−1. Type 2 laminates with fibers running perpendicular to specimen length (fiber orientation of 90° with respect to specimen span length) enable measuring intra‐laminar (matrix/fiber) peel strength (ILPS) for tensile (mode I) strength of the matrix/fiber interface with locus of failure at beam bottom ply. Thirty‐six type 2 laminates are tested at three levels of flexural strain rates: 2.09 * 10−5 to 3.49 * 10−3 s−1. For each level of strain rate, Weibull plots are constructed. Stress values at failure probability (Pf) of 63.1% are assigned as strength values. The results show a slight decrease of the Weibull modulus, m, with increasing strain rates. The modulus decreases from 12.37 to 10.49 and from 11.11 to 9.68, for laminates type 1 and 2, respectively. For laminates type 1, ILSS increases with increasing strain rates rising 16.1% over the range of the tested strain rates. For laminates type 2, ILPS increases with increasing strain rates rising 38.1% over the range.

In-situ constructing ultra-high-aspect-ratio core–shell nanostructures to achieve high-performance epoxy thermosets and their carbon fiber reinforced epoxy composites

Using block copolymers to improve the mechanical properties of materials was a promising method, and the effect was positively correlated with the aspect ratio of the nanostructures. However, except for worm-like and branched worm-like nanostructures, nanostructures with higher aspect ratios have not been reported so far and its forming methods was unknown. In this paper, a feasible approach was provided to in-situ construct ultra-high-aspect-ratio core–shell nanostructures in epoxy, and the morphology evolution during the epoxy preparation process was clarified. It was shown that the tensile strength, elongation at break, fracture toughness and tensile modulus of the nanostructured epoxy were simultaneously improved when the content of block copolymer was as low as 1.75 wt%, achieving 93.6 MPa (31.3% improved), 7.9% (79.5% improved), 133.5 N/mm3/2 (184%) and 2693 MPa (5.6% improved), respectively. The interlaminar shear strength (ILSS) of the corresponding carbon fiber reinforced polymer (CFRP) composites was 32.5% higher than that of the control CFRP composites. Meanwhile, it was worth pointing out that the glass transformation temperatures (Tg) of the modified epoxy matrices and their corresponding CFRPs were similar to those of the unmodified materials. The improvement mechanisms on tensile strength, toughness and ILSS were also systemically investigated. It was expected that this work could provide a feasible routine for in-situ constructing complex morphological nanostructures in epoxy resins and some new ideas for the design of next-generation advanced composites.

Material and structural testing to improve composite tidal turbine blade reliability

Most tidal turbine blades are currently made from glass or carbon fibre reinforced epoxy composites. These represent a significant part of the turbine cost, but few data are available either to validate current safety factors or to propose alternative more environmentally-friendly materials. This study, performed within the EU H2020 RealTide project, aimed to provide these data. First, a detailed investigation of the static and fatigue behavior was performed at the coupon scale, including not only those materials currently used, but also alternative recyclable thermoplastic matrix composites and natural fibre reinforced materials. Tests were performed before and after seawater saturation, in order to quantify the change in design properties with water uptake. Then a first full scale 5 meter long composite blade was designed and tested to failure. A specific test frame was built, allowing loads up to 75 tons to be applied and simulating the applied moments corresponding to service loads. Static and cyclic loads were applied and extensive instrumentation was used to detect changes in behavior, inluding optical fibres implanted during manufacture, acoustic emission recording, and specific instrumentation developed within the project.
 The results have enabled numerical simulations to be verified, and this has provided confidence in the modelling tools. These were then employed in order to propose an improved design of a lower cost blade.

Investigation of mechanical properties of hybrid stainless steel/acrylic and carbon fiber reinforced epoxy composite

Hybrid composite specimens were produced with stainless steel-acrylic (SSA) and carbon fiber reinforcement in order to achieve ductile behavior compared to CF reinforced epoxy composites. Laminated composites containing CF and SSA fabrics in with different ply configurations were manufactured using vacuum infusion method. In addition, CF fabric was used in two different ply orientations (0–45°). In both the flexural and tensile test results, composites having CF oriented at 0° showed higher strength and modulus but lower strain than composites having CF oriented at 45°. When the number of carbon fiber layers increased, the composites showed high strength and modulus, but low strain. Increasing the number of SSA significantly increased the flexural and tensile strains of laminated composites. After the mechanical tests, the fracture surfaces of the specimens were examined with an optical microscope and matrix cracks, fiber breakage, fiber pull-out and delamination failures were observed.

Innovative wicking and interfacial evaluation of carbon fiber (CF)/Epoxy composites by CF tow capillary glass tube method (TCGTM) with Tripe-CF fragmentation test

For improvement of mechanical property and manufacturing efficiency of fiber reinforced composites, wettability, which was affected by temperature, viscosity, the pressure of resin injection, fiber volume fraction, fiber array, and so on, was important factor, which had been focused many researchers. Although the wettability during manufacturing processing was usually evaluated by the permeability, it does not contain the surface energies for the fiber and matrix. Using innovative CF tow capillary glass tube method (TCGTM), this study investigated the wetting, wicking and interfacial properties for three type CFs reinforced epoxy composites combined with a triple-fiber fragmentation test. The CFs TCGTM was performed to evaluate wettability and wicking of CF tow with epoxy resin by measuring height of impregnated epoxy front in capillary tube more practically. After curing the specimens, contact angle between CF and epoxy was measured using FE-SEM photos directly. Wetting and wicking were also evaluated by measuring the impregnated length of epoxy droplets on CF tow, and compared with result by CF TCGTM. From all of the relating tests, the 50C type CF exhibited better wetting and wicking than 60E type CF and the desized CF. Interfacial shear strength (IFSS) were evaluated using a triple-fiber fragmentation test for three different type CFs. Better IFSS of the 50C type CF was consistent with wetting and wicking results by CFs TCGTM. A new innovative CF TCGTM can be applicable for conventional CF reinforced epoxy composites more practically by combining with micromechanical test for the IFSS between single CF and epoxy mainly.

The development of high performance hybrid joints between epoxy composites and PEEK/PPS composites: The mode-II and mix mode-I/II fracture behaviour

The development of effective methods for the bonding of Poly-etherether-ketone (PEEK) and Polyphenylene-sulphide (PPS) composites to thermoset composites is appealing to expand their applications in aerospace industry. Herein, the surfaces of PEEK and PPS composites were treated by a high-power UV-irradiation technique for 6 s, that proved to significantly improve their intrinsically low surface activities. Carbon fibre reinforced epoxy composites were then directly cured onto the PEEK and PPS composites with or without an aerospace film adhesive at the joining interfaces. The mode-II and mix mode-I/II fracture behaviour of the hybrid joints were studied using an end notched flexural test and a fixed-ratio mixed-mode test, respectively. It was observed that the failure of the hybrid joints without adhesives mainly took place at the joining interfaces. In this case, the lack of resins at the fracture plane resulted in relatively low fracture toughness. Encouragingly, a cohesive failure was observed for the hybrid joints with adhesives in all the cases, owing to the enhanced adhesion between the adhesive and the PEEK/PPS composites upon the UV-treatment. This phenomenon indicated that optimal fracture resistance of the hybrid adhesive joints was obtained for the given material systems.

Low-velocity impact response of MWCNTs toughened CFRP composites: Stacking sequence and temperature effects

Despite impressive specific mechanical properties, carbon fiber reinforced polymer (CFRP) composites are strongly susceptible to impact events due to their low interlaminar fracture toughness which fosters delamination phenomena detrimental to the residual mechanical properties of the laminate. The incorporation of nano-fillers in the neat matrix is a suitable way to improve both Mode I and Mode II CFRP fracture toughness. In view of this, the present work assessed the toughening effect of multi-walled carbon nanotubes (MWCNTs) on the impact and post-impact response of carbon fiber reinforced epoxy composites evaluating the effect of two key design parameters: ply stacking sequence and operating temperature. Two stacking configurations, i.e., cross-ply (CP) and quasi-isotropic (QI), and three testing temperatures, i.e. −40 °C, room temperature and +80 °C, were considered. The results highlighted a higher damage tolerance of QI laminates characterized by a superior residual flexural strength than CP for all impact energies and temperatures. Moreover, the toughening effect played by MWCNTs on QI samples was disclosed for all temperatures with an improvement in the normalized residual flexural strength up to 10%. The enhanced damage tolerance must be ascribed to the bridging effect and the pull-out phenomena provided by CNTs which delay matrix cracks opening and propagation.

Fast and sustainable recycling of epoxy and composites using mixed solvents

Chemical recycling of thermosets and composites can reclaim polymer matrix and high-value reinforcement to protect the environment and save resources. However, efficient and sustainable chemical recycling of epoxy thermosets is still a significant challenge, specifically, improving the decomposition rate, easily separating and reusing the decomposed components under mild condition. Herein, we report the fast and sustainable recycling of epoxy and composites by small-molecule assisted bond exchange reaction (BER) in a mixed solvent. The anhydride-cured epoxy resin with embedded catalyst was rapidly decomposed by the mixed solvent containing a high boiling point alcohol and inert good solvent via transesterification below 150°C at normal pressure. The epoxy decomposition rate was optimized by altering the good solvent types and solvents mixing ratios. We found the epoxy decomposition rate was the fastest in dimethylformamide/ethylene glycol (50/50) due to balanced solvent diffusion/swelling and reaction rate. After epoxy decomposition, the depolymerized epoxy oligomer (DEO) and residual solvents were readily separated by reduced pressure distillation below 80°C. The DEO as an additive (up to 20%) was repolymerizated with fresh epoxy resin to make epoxy materials, which showed similar mechanical properties to the original epoxy with slight deterioration even for several recycling cycles. The reclaimed solvent was used for the next round of recycling. With the optimized condition, carbon fiber reinforced epoxy composite was also recycled to reclaim the high-value carbon fiber with unchanged mechanical properties. This work presents a sustainable and fast recycling paradigm for industrial-grade epoxy and composite with potential for upscale engineering applications.

Energy absorption in carbon fiber honeycomb structures manufactured using a liquid thermoplastic resin

In this study, carbon fiber/thermoplastic (Elium®) honeycombs were manufactured using the resin infusion process in a customized metallic mold. Honeycomb cores, based on different carbon fiber layers, were manufactured to achieve four different fiber weight fraction composites. Two different types of specimens, based on a single honeycomb cell and five honeycomb cells, were prepared and subjected to compression loading. The results of these tests were compared with data from similar honeycomb structures based on carbon fiber–reinforced epoxy composite. It has been shown that the compressive strength and the specific energy absorption capacity of the honeycombs increase rapidly with increasing fiber weight fraction. The specific energy absorption capability of the novel thermoplastic honeycomb structures has been shown to be as high as 50 kJ/kg which compares favorably with other energy-absorbing core materials. The thermoplastic honeycomb specimens exhibited a similar specific energy absorption capability and an improved compressive strength compared to their epoxy counterparts. Furthermore, the CF/thermoplastic honeycombs exhibited enhanced structural stability and displayed a more uniform and progressive core failure mode than the longitudinal splitting observed in the CF/epoxy honeycombs. The honeycomb core that exhibited the best performance was then used to manufacture thermoplastic sandwich specimens based on CF/thermoplastic face sheets. Three point bend tests were conducted to determine the flexural strength of the sandwich samples and to identify the failure modes. Optical micrographs revealed that the flexural damage was primarily due to the core crushing and adhesive failure between the core and the composite skins.

Mechanical properties, thermal stability and microstructure evolution of carbon fiber-reinforced epoxy composites exposed to high-dose γ-rays

Carbon fiber-reinforced composites with superior strength-to-weight and stiffness-to-weight ratio were highly resistant to ionizing radiation, which make them popular in nuclear reactor. There were large doses of γ-radiation in nuclear reactor, which caused damage in composites. In order to investigate effect of high γ-ray absorbed dose on carbon fiber (CF)/epoxy (EP) composite, the doses of 2 MGy, 7 MGy, and 20 MGy were applied in irradiating the samples, and the mechanical properties, thermal stability and microstructural changes of composites were analyzed. The results showed that under the absorbed dose of 2 MGy, the storage modulus, flexural strength and thermal stability of CF/EP composites increased. However, those properties decreased while the dose increased to 7 MGy and further decreased while the dose rise to 20 MGy. The evolution mechanism was understood by analyzing free radical and composition change of CF/EP after irradiation via electron spin resonance and X-ray photoelectron spectroscopy. Irradiation results in bond-breaking such as C–C bond and C–H bond, and also new bond-forming like C–O and CO, which forms competition effects among radiation-induced degradation and cross-linking reaction.

Electromagnetic shielding characteristics of carbon and glass fiber composites

Electromagnetic shielding characteristics for orientation angle and number of plies of carbon fiber reinforced epoxy composites were investigated in the frequency range between 900 and 6000 MHz. In this study, both unidirectional and bidirectional carbon fiber fabrics were utilized as reinforcement materials to manufacture the composite samples. Twill bidirectional glass fiber fabrics were also used in order to provide a large amount of flexibility. To prepare the composite laminates for measurement, hand lay-up method was preferred. Measurements were carried out by using DFG 4060 signal generator and HF 60105 spectrum analyzer. According to the measurements, it was observed that electromagnetic shielding effectiveness (EMSE) was very higher when the orientation angle of the carbon fiber was 90°, as compared to 0°. Another parameter that affects EMSE is whether the carbon fiber fabric used is unidirectional or bidirectional because it was observed that the bidirectional fabric increased EMSE. In addition, it has been determined that the number of plies has less effect on EMSE than the orientation angle.

Experimental and multiscale modeling investigations of cryo-thermal cycling effects on the mechanical behaviors of carbon fiber reinforced epoxy composites

In cryotank applications, carbon fiber reinforced epoxy composites are required to face the challenge of extreme cryo-thermal cycles while rare relevant research work has been conducted. This paper reports cryo-thermal cycling effects on the mechanical behaviors of carbon fiber reinforced epoxy composites via experimental and multiscale finite element method (FEM) investigations. Four types of cryo-thermal cycling are designed to explore the roles of the cycling number and the cycling period under normal and severe conditions. Unidirectional and orthotropic laminates are prepared to demonstrate intralaminar and interlaminar expansion mismatch phenomena. For unidirectional laminates, the transverse tensile strength shows a dramatic initial decrease of 18.7%, 21.2%, 4.1% and 17.4% while the interlaminar shear strength is lowered by 4.9%, 14.2%, 5.1% and 14.0% after cryo-thermal cycling for four cycle types, respectively. Meanwhile, it is exhibited that the interlaminar shear strength of orthotropic laminates is reduced by 17.1%, 18.1%, 13.1% and 17.9%, respectively. Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) measurements are executed to detect the secondary curing. Based on the constitutive relationship affected by temperature and moisture absorption, a microscale unit cell with random fibers and a specimen-sized model with cohesive elements are established to reveal the intralaminar and interlaminar damage evolutions during cryo-thermal cycling. After elucidating typical damage modes, such as interface debonding, matrix microcracks, surface frost heave and interlaminar gap generating, the multiscale FEM model is modified to evaluate mechanical degradations quantitatively, which gives reasonable explanations for experimental results and provides an efficient and convenient method for composite design.

Investigation on interlaminar behavior of different morphology GO structured carbon fiber reinforced epoxy composites

In this study, the deoxygenation of exfoliated graphene oxide (GO) was employed to fabricate different morphology GO structured carbon fiber (CF) via electrophoretic deposition. It was found that the deposition morphology of GO on CF was closely related to its oxygen content. Meanwhile, the interfacial behavior of the final composites greatly depended on the adhesion morphology of GO. The transverse bundles fiber test (TFBT) and interlaminar shearing strength (ILSS) revealed that the pitaya-like GO structured CF (CF/GO13) composites displayed a superior interlaminar performance. The TFBT and ILSS of CF/GO13 composites reached as high as 31.9 MPa and 77.3 MPa, which was 42.56% and 50.5% higher than that of virgin CF composites, respectively. Besides, the CF/GO13 composites displayed an excellent resistance to high-low temperature cycling, only showing 7.09% reduction in ILSS after cycling for 10 times. The present study provided a reliable guidance for optimizing interfacial properties of the composites via regulating the morphology of two-dimensional nanomaterials on CF.

Hierarchical Composite Materials

Conventional continuous fiber reinforced polymer composites (FRP) have extensively been used as structural elements in a myriad of sectors, such as civil, transport, energy and marine, among other, due to their superior mechanical properties, low weight and ease of processing. However, the relatively weak compression and interlaminar properties of these composites limit their application field. Interest is, therefore, growing in the development of hierarchical or multiscale composites, in which, a nanoscale filler reinforcement is utilized to alleviate the existing limitations associated with the matrix dominated properties. The majority of the work has focused on carbon nanotubes, CNTs due to their extraordinary intrinsic properties. In addition to their outstanding mechanical properties, CNTs possess excellent electrical and mechanical properties, making them attractive materials as reinforcement for polymer matrices. CNTs provide both intralaminar and interlaminar reinforcement, thus improving delamination resistance and through thickness properties, without compromising in-plane performance. In recent years, there has been an increasing interest in the use of graphene as reinforcement of polymer nanocomposites. Compared to CNTs, graphene has advantages such as lower cost, higher surface area and a greater ease of processing. Graphene is more easily dispersed in the resin and causes a lower viscosity increase, which can facilitate the impregnation of the fibers. In this work, the fabrication and characterization of hierarchical composites are analyzed through the inclusion of graphene to conventional continuous carbon fiber reinforced epoxy composites by vacuum-assisted resin transfer molding.

Effect of Nanofiller on the Mechanical Properties of Carbon Fiber/Epoxy Composites under Different Aging Conditions.

In this study, carbon fiber-reinforced epoxy composites (CFRPs) containing multi-walled carbon nanotube (MWCNT) and halloysite nanoclay were fabricated. The effects of these nanofillers (MWCNT and nanoclay) on the tensile and flexural properties of the CFRPs under different aging conditions were studied. These aging conditions included water soaking, acid soaking, alkali soaking, and thermal shock cycling. The experimental results showed that, after accelerated aging, the mechanical performance of the CFRPs decreased. The performance degradation in the soaking environment depends on the immersion temperature and immersion medium. High-temperature accelerated the aging behavior of the CFRPs, resulting in low strength and modulus. The CFRPs were more vulnerable to acid soaking and alkali soaking than water soaking. The MWCNT and halloysite nanoclay are beneficial to improve the immersion aging resistance of the CFRPs, and the additions of nanofillers delayed the performance degradation under immersion aging conditions. However, nanofillers hardly improve the aging resistance of the CFRPs under thermal shock cycling condition. The fracture morphologies were observed by scanning electron microscopy (SEM) to reflect the failure modes of the CFRPs under various aging conditions. Differential scanning calorimeter (DSC) and fourier transform infrared (FTIR) spectroscopy tests were used to estimate the changes in the chemical structures and properties of epoxy resin and its composites under different conditions.

Liquid oxygen compatibility of epoxy matrix and carbon fiber reinforced epoxy composite

Liquid oxygen compatibility is the key to evaluating whether carbon fiber reinforced epoxy composites (CF-composite) can be used in liquid oxygen environment. In this work, DOPO-PGE was prepared to improve the liquid oxygen compatibility of epoxy resin and CF-composite. The FTIR, 1H and 31P NMR spectrum was used to confirm the chemical structure of DOPO-PGE. According to the UL94 test results, TG-FTIR, char residue analysis, and XPS analysis, the mechanism of DOPO-PGE affecting the liquid oxygen compatibility of epoxy resin is mainly attributed to the fact that the radical PO released in the initial thermal decomposition stage of DOPO-PGE/epoxy can capture the highly active radical H, O, HO and terminated the radicals’ chain exothermic reactions. The CF-composites show better liquid oxygen compatibility than epoxy resin matrix. However, the long-term liquid oxygen immersion can deteriorate the liquid oxygen compatibility of CF-composites.

Effect of graphene oxide/graphitic nanofiber nanohybrids on interfacial properties and fracture toughness of carbon fibers-reinforced epoxy matrix composites

The fracture toughness of carbon fiber-reinforced epoxy composites (CFRPs) is greatly dependent on the interfacial adhesion between the carbon fibers and the epoxy matrix. Introducing nanofiller reinforcements into the interface is an effective approach to enhancing the interfacial adhesion of CFRP. In the present study, a simple and efficient method is proposed for the deep and stable penetration of graphene oxide/graphitic nanofiber nanohybrids (GO-GNFs) into an epoxy matrix as a CFRPs. To confirm the efficiency of the proposed method, CFRPs are fabricated with various amounts of (i) untreated GNFs, (ii) dry-ozonized GNFs, and (iii) GO-GNFs. For all three types of composites, the optimal nanofiller content is found to be 0.8 wt%. The addition of GO-GNFs is shown to increase the inter-laminar shear strength by 159.5%, and the fracture toughness by 102.8%, compared to those of the pristine CFRPs. The reinforcing mechanisms are explored by analyzing the surface properties of GO-GNFs and the wettability between fiber and nanofillers within the epoxy matrix, are ascribed to the maximal polar component of surface free energy and the minimal contact angles. This approach shows that the GO-GNF composite is a simple and efficient method for the preparation of CFRPs with excellent interfacial adhesion, which has potential applications in the structural composite industry.

Modeling and evaluation of dynamic degradation behaviours of carbon fibre-reinforced epoxy composite shells

In this study, a segmented degradation model was established for the first time to predict and evaluate the dynamic degradation characteristics of carbon fibre-reinforced epoxy composite (CFRC) shells accurately by considering temperature variations during heating, maintenance, and cooling. The model is based on the Reddy's high-order shear deformation theory, complex modulus method, and coefficient fitting approach. First, explicit expressions of material parameters and thermal expansion coefficients (TECs) in different thermal degradation stages were proposed, followed by the derivation of the differential equations to solve the structural dynamic degradation characteristics. Moreover, an identification method for the fitting coefficients of the CFRC material was described, which is based on experimental tests and iterative calculations of elastic moduli, loss factors, and TECs at different degradation time points in different thermal degradation stages. Finally, the natural frequencies, damping ratios, and time-domain responses were measured using a novel testing system for the dynamic degradation of specimens subjected to a pulse excitation load to validate the developed model. Theoretical and experimental results indicate that the natural frequencies decreased as the degradation time increases at the heating-up and temperature maintenance stages, whereas they increased at the cooling stage. However, an uptrend in the damping and response behaviours was observed in the first two stages, whereas a downtrend was recognized at the cooling stage.