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Thin-walled coilable composite shells have been successfully used in deployable space payloads due to their high storage efficiency and stiffness-to-weight ratio. However, in real-life applications the deployable composite shells requiring repeatable coiling up and deployment are easy to be damaged, and their damage or failure behaviors due to large deformations has been rarely studied. This paper aims to investigate their damage and failure behaviors during the snap through, equal-sense and opposite-sense coiling up. First, multiscale models are established to compute the mechanical properties of plain-woven fabrics and unidirectional prepregs with consideration of stiffness reduction of the composites. Then, damages of each ply within the thin-walled shell are studied during snap through and coiling up. Simultaneously, effects of hub diameter on the damage of the thin-walled shell were investigated, followed by experimental verification using strain gauges and a scanning electron microscope (SEM). Simulation and experimental results show that the dominated damage of the thin-walled shell is failure of matrix. The SEMs of the edge damaged show failures of both resin and carbon fibers. Tensile damages of matrix can be relieved as the increment of the hub diameter, and no obvious failure is observed at the hub diameter of 50 mm. [Display omitted] • Multi-scale models with consideration of stiffness reduction are set up. • Damages of deployable composite shells during coiling up are analyzed. • Effect of hub diameter on the damages of composite shells is investigated. • Strains of the shell are experimentally measured to validate simulation results. • Edge damage during equal-sense coiling up is investigated via SEM. [ABSTRACT FROM AUTHOR]

To achieve better interfacial adherence of carbon fibers to the epoxy resin, the graphene modified with ammonia and 3-Glycidyloxypropyl trimethoxysilane (GPTMS) was utilized to modify the epoxy resin. Subsequently, a simple two-step method of wet impregnation and the thermoforming process was employed to fabricate the CF/graphene-modified epoxy (CF/EG/EP) composites. The interfacial properties of CF/EP composites were studied using microdroplet debonding and short-beam shear tests on modified graphene (MEG). It is shown that the incorporation of GPTMS-modified graphene into the CF/EP composites strengthened the interfacial and bending properties of CF and matrix, resulting in a 12.5 % growth in interlaminar shear strength (ILSS) and 22.5 % growth in flexural strength of the CF/EP composites, respectively. Meanwhile, scanning electron microscope images confirmed the effectiveness of the GPTMS-modified graphene in improving the interfacial compatibility and adhesion of CF/EP composites. [Display omitted] • Carbon fiber-reinforced epoxy modified by MEG composites are fabricated by an impregnation-thermoforming process. • The ILSS and IFSS of CF/MEG/EP composites are compared. • The flexural strength and modulus of CF/EMEG/EP composites can be increased to 1665.4 MPa and 140.2 GPa, respectively. [ABSTRACT FROM AUTHOR]

Geological hazards of sand layers pose a serious threat to engineering safety. Grouting reinforcement technology is widely used in such conditions due to its convenience, economy, and effectiveness. To explore the reinforcement effect of carbon fiber (CF) modified cement-based grouting materials on sand layers, grouting solidified bodies (GSB) with CF contents of 0.0%, 0.5%, 1.0%, and 1.5% are selected for Split Hopkinson Pressure Bar (SHPB) impact tests, scanning electron microscope (SEM) scanning, and numerical simulation experiments. The mechanical properties of specimens under dynamic impact conditions and the reinforcement mechanism of CF are studied. Results show that GSB is a strain-rate-dependent material. With the increase of impact rate, peak stress, incident energy, transmitted energy, and dissipated energy of specimens gradually increase, while the integrity of specimens decreases. The CF content remarkably affects the mechanical properties of specimens. When the impact rate is constant, with the increase of CF content, the peak stress and transmitted energy of specimens show a decreasing–increasing– decreasing trend, and the performance of CF-1.0% specimens is optimal. The cement matrix is the main energy storage and release medium, accounting for 97.66% of the energy. When damaged, the cement matrix is mainly fractured. At the microcrack tip, CF influences the direction of crack propagation, reducing the radius of crack propagation, and the main failure mode of CF is debonding. CF can substantially improve the mechanical properties of specimens and reduce the number of cracks. Compared with CF-0.0%-cementitious material (CM) specimens, the peak stress of CF-1.0%-CM specimens is increased by 19.98%. The magnitude of CF force is related to the angle between crack and CF. As the angle increases from 0° to 90°, the CF force gradually increases, reaching the maximum at 90°, with an increase of 133.82%. At this angle, the anti-cracking effect of CF is most substantial. The research results can provide technical support for sand layer grouting reinforcement technology. • Explore carbon fiber (CF)'s effect on GSB dynamic behavior through SHPB tests. • Explore CF's toughening and anti -cracking mechanisms through SEM tests. • Perform 3D simulation analysis of stress distribution and failure in specimens. • Conducting numerical simulations to explore the toughening mechanism of CF [ABSTRACT FROM AUTHOR]

The surface topography and interface characteristics play a significant role in determining the mechanical properties of carbon fiber reinforced polymer (CFRP) composites. These features are primarily influenced by the surface chemical structures and their interactions with the matrix resin. Here, we developed a rigid-flexible coating consisting of polyetheramine (PEA) and polydopamine (PDA) on the fiber surface to control the interface and improve the mechanical properties of CFRPs. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectrum (FT-IR) results validated the successful introduction of polymeric chains and fiber surface characteristics including rough surfaces, slim polymer layers and uniform dots were examined by scanning electron microscope (SEM) and transmission electron microscopy (TEM). Contact angle tests indicate that the functionalized coating noticeably enhances the interaction force between carbon fibers, promoting improved wettability by the matrix resin. The bending and interlaminar shear strength of CFRP prepared by functional carbon fiber are increased by 45.76 % and 47.63 %, respectively. The drop weight impact (DWI) test confirms the positive effect of improved interfacial properties on the out-of-plane impact resistance of CFRPs. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Obtaining CuCo 2 O 4 /CF that can realize the dual function of catalytic and cathodic. • Different morphological features and hydrophilicity were exhibited at different hydrothermal temperatures. • Cu(II)/Cu(I) and Co(III)/Co(II) reactive centers provide excellent catalytic performance. Cobalt-based oxide CuCo 2 O 4 -loaded CuCo 2 O 4 /carbon felt (CF) composite cathodes were synthesized by hydrothermal deposition of a precursor of Cu/Fe oxides on CF followed by roasting in air. The material serves both catalytic and cathodic dual functions in the heterogeneous electro-Fenton (EF) process. Through XRD (X-ray diffraction), FTIR (Fourier transform infrared spectroscopy), XPS (X-ray photoelectron spectroscopy), SEM (scanning electron microscope), and catalytic experiments, it was concluded that CuCo 2 O 4 loading was successful and the highest hydrophilic 180-CuCo 2 O 4 /CF was obtained by varying the hydrothermal temperature without destroying the original structure. 180-CuCo 2 O 4 /CF accomplished 98.03 % degradation in 60 min, and it was found to maintain high degradation capacity in the pH 3 ∼ 9 range in experiments where the experimental parameters were varied. Compared to monometallic oxides, Cu and Co dual active centers are integrated in CuCo 2 O 4 , giving it diverse redox properties and oxidation states. As a result, the CuCo 2 O 4 /CF material can realize the dual function of catalytic and cathodic, which provides a new development direction in practical wastewater treatment. [ABSTRACT FROM AUTHOR]

This paper investigates the fundamental mechanical properties of tension, bending, shear, and torsion for unidirectional carbon fiber-reinforced polymer (CFRP) plates. First, the mechanical properties of tension, bending, shear, and torsion for the unidirectional CFRP plates are tested, and the test results of relevant mechanical parameters are statistically analyzed. Secondly, the failure modes and damage evolution processes are analyzed by observing the failure surface using the scanning electron microscope (SEM). Subsequently, the probabilistic characteristics of the statistical results for the mechanical parameters are analyzed. The parameter fitting is performed using the Normal, Log-normal, and Weibull distributions for goodness-of-fit analysis, respectively. Finally, the appropriate probability distribution types for the mechanical performance parameters of CFRP plates are proposed. • Mechanical properties of unidirectional CFRP plates are experimentally investigated for probabilistic characteristics. • The failure modes and damage evolution of CFPR plates under tension, bending, shear, and torsion are analyzed using SEM. • Probabilistic distribution of mechanical properties is discussed using Normal, Log-normal, and Weibull distributions. [ABSTRACT FROM AUTHOR]