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This study presents an investigation on the mechanical properties and failure mechanisms of composites made of plain woven fabrics reinforced with carbon fibers, aramid fibers, and their intralayer hybrids. The specimens were fabricated by hand lay-up method. Tension, compression, and shear tests were performed in accordance with the relevant standards to investigate the tensile, compression, and shear properties of carbon fiber, aramid fiber, and carbon/aramid fiber intralayer hybrid plain woven composites. Accurate strain field was obtained by digital image correlation (DIC) technology and compared with the results measured by the strain rosettes. Furthermore, a multi-scale modeling strategy was developed to predict the mechanical properties of the hybrid composites. The fiber monofilament model was used to calculate the effective properties of carbon and aramid yarns at the micro-scale level. Representative volume element (RVE) models of the hybrid composite were constructed considering the real fabric pattern at the meso-scale level. The predicted results agree well with the experimental data which validates the multi-scale modeling strategy. The presented information on the tensile, compressive, and shear properties and finite element simulation method of carbon/aramid intralayer hybrid composites should be useful in subsequent research as well as in designing new high-performance composites and structures. [ABSTRACT FROM AUTHOR]

In this paper, the effect of interlaminar properties and the type of delamination defects on the residual compression properties of carbon fiber laminates were experimentally investigated. A new method, which employed magnetic force to guide the arrangement direction of stainless steel particles between layers of laminates, was adopted to improve the interlayer toughness. The digital image correlation, C-scan, and micro-CT were used to measure and identify the compression failure damages. Test results showed that the compressive strength of the intact carbon fiber laminates was 299.37 MPa, and the one of specimens containing the deeply buried delamination, the through-width delamination, and the surface delamination decreased by 55.98 MPa, 58.69 MPa, and 60.23 MPa, respectively. The compressive strength of the specimens containing the deeply buried delamination only decreased by 14.01 MPa when the mode I toughness increased by 81.88%, and the specimen containing the surface delamination only decreased by 30.86 MPa when the mode II fracture toughness increased by 87.72%. However, improving the fracture toughness could not strengthen the specimens containing the through-width delamination. Moreover, a qualitative dynamic damage relationship, which described the relationship between delamination expansion and compression damage vividly, was proposed. The reason the increase of the toughness could improve the residual compression performance of the laminates containing delamination was that the higher fracture toughness hindered the secondary expansion of the delamination during the compression process so that the delamination area could almost remain unchanged. [ABSTRACT FROM AUTHOR]

To enhance the interlaminar shear strength of carbon fiber/epoxy resin laminate, stainless steel particles were filled between laminas and uniformly arranged along the thickness direction by the outside magnetic field during manufacturing the composites. Specimens with five particle densities of 15 g/m2, 30 g/m2, 45 g/m2, 60 g/m2, and 75 g/m2 were prepared for testing. The interlaminar shear strength was obtained by short beam shear test and compared with the one of specimens without particles and with the randomly distributed particles between layers. Both modified equivalent stiffness predicting model and bridging model were established. A segmented prediction model was proposed by combining the two models. The error between results obtained by the proposed model and test was less than 10%. Results showed that the interlaminar shear strength of all specimens filled with particles was improved except for the one with particle density of 15 g/m2. The interlaminar shear strength of the specimens with randomly distributed particles between layers increased by 6.12%, 7.29%, 7.43%, and 6.01% for specimens with particle densities of 30 g/m2, 45 g/m2, 60 g/m2, and 75 g/m2. The interlaminar shear strength of the specimens with magnetically guided particles aligned along the thickness direction increased by 9.78%, 14.39%, 17.93%, and 20.39% for the four particle densities. This indicated that the interlaminar shear strength of the carbon fiber/epoxy laminate could be effectively enhanced by aligning the particles between laminas along the thickness direction using the outside magnetic field guidance during manufacturing the composites. • The interlayer toughened carbon fiber/epoxy laminates with magnetically guided steel particles are manufactured. • The enhancement of interlaminar shear strength (ILSS) of the interlayer toughened composites is studied experimentally. • Two models are established to predict the ILSS of the interlayer toughened composites. • The vertically arranged particles can effectively reduce the delamination and affect the ILSS to a greater extent. [ABSTRACT FROM AUTHOR]

• Effect of thermal cycling on the mechanical properties of carbon fiber/epoxy laminated composites was investigated. • The residual tensile and in-plane shear moduli decrease rapidly during the initial thermal cycles. • The reduction ratio of the residual in-plane shear modulus is larger than that of the residual tensile modulus. • Different fiber materials affect the residual tensile and in-plane shear moduli of the laminates exposed to thermal cycling. Carbon fiber reinforced polymer (CFRP) composites are commonly used for reflectors of artificial satellites operating in low earth orbit (LEO). The decay of the modulus of the CFRP composite varies under different thermal cycling environments, which can lead to a reduction in the accuracy of the reflector panels, affecting the transmission of signals. This paper investigates the impact of different thermal cycling conditions on the mechanical behavior of carbon fiber/epoxy laminated composites experimentally. Three kinds of thermal cycling conditions involving continuous temperature changes are employed to explore the influence of temperature range on the residual tensile and in-plane shear moduli of the laminates. Test results indicate that the upper temperature limit and the temperature span of the thermal cycling conditions jointly affect the mechanical properties of CFRP composite laminates, but the responses of the residual tensile and in-plane shear moduli are different under the variation of each temperature parameter alone. The residual tensile and in-plane shear moduli of the laminates under thermal cycling decrease with an expansion of the temperature span having the same upper limit. If the temperature span remains constant, an increase in the upper temperature limit leads to an increase in the residual tensile modulus, but a decrease in the residual in-plane shear modulus. The main damages causing the decay of residual tensile and in-plane shear moduli of unidirectional laminates were investigated by scanning electron microscopy (SEM) technology. Observations of the microscopic fracture of the material show that the post-curing reaction factor predominantly influences the residual tensile modulus of unidirectional laminates, while the fiber/matrix interface damage factor dominates the residual in-plane shear modulus of the unidirectional laminates. Furthermore, an increase in the fiber tensile modulus decreases both residual tensile and residual in-plane shear moduli. Notably, the residual in-plane shear modulus exhibits greater sensitivity to thermal cycling compared to the residual tensile modulus. The findings reported in this paper would provide valuable insights and guidance for the design and application of carbon fiber/epoxy composites subjected to thermal cycling conditions. [ABSTRACT FROM AUTHOR]

• Strain rate effects on the tensile and shear strength of carbon fibre composites were investigated. • The strain rate effect of the composite material was considered in VUMAT for simulations. • High-velocity impact responses with different impact velocities and angles were tested and simulated. • Failure behaviours and energy absorption mechanisms were analysed and discussed. In this paper, the tensile and in-plane shear behaviors of carbon fiber reinforced laminated composites (CFRLCs) under high strain rate loading were experimentally investigated. The strain and damage processes of the specimens were obtained using the Digital Image Correlation (DIC) method and a high-velocity camera. Quasi-static test results were used as the control group for obtaining the dynamic correction factors of the material system under high strain rate conditions. In addition, high-velocity impact (HVI) tests with different impact velocities and angles were conducted on CFRLCs. The dynamic correction factors were used in HVI simulations to consider the effect of strain rate. The energy absorption mechanisms and failure modes of laminates under different impact conditions were analyzed using testing and simulated results. It is found that during the HVI, matrix tension and fiber tension failures are the main failure modes. The energy absorbed by the laminate in oblique impact is larger than the one in normal impact. The possible reason is that the increase rate of the damage area with the four failure modes in oblique impact is larger than the one in normal impact. [ABSTRACT FROM AUTHOR]

• The impact resistance and damage tolerance of carbon fiber composite laminates were experimentally investigated. • In the process of high-velocity impact, the main failure modes are fiber shear and tension failure. • Compression after impact (CAI) were performed on laminates with different impacted positions. • The CAI damage of laminates impacted at the central position is main delamination buckling. In this paper, the impact resistance of carbon fiber/resin composite laminates with a thickness of 2.5 mm at different impact velocities, angles and positions was investigated experimentally. In the process of high-velocity impact, fiber shear failure and tension failure are the main failure modes. When the impact velocity is 300 m/s, the fiber tension failure and matrix compression failure under oblique impact are more than that under normal impact, and the energy absorption of laminates is also lager than that under normal impact. The ballistic limits, energy absorption and delamination area of the center and edge impact of laminate are similar. In addition, the CAI tests are conducted to study the influence of different positions on the residual compressive strength of laminates after high-velocity impact, and the fracture loads and failure modes of two impact positions are quite different. The failure modes of the center impact laminate are main buckling failure, and the failure modes of the edge impact laminate are compression failure near the bullet hole side of the fixture and buckling failure near the center of the laminate. The research results can provide a reference for the residual strength of laminates after impact at different locations in practical situations. [ABSTRACT FROM AUTHOR]

In this paper, a plain-woven metamaterial consisting of a ribbon-like blend of carbon fiber-glass fiber strips is proposed. The structure of the proposed hybrid material has a broadband filtering function of electromagnetic wave, can form beam reconstruction and selective wave transmission, and reduce radar scattering cross section (RCS) in the 9 GHz - 25 GHz frequency band. The macroscopic equivalent mechanical parameters are estimated by constructing the micro fine structure model and combining the periodic boundary conditions. The Hasin failure criterion is used to predict the progressive damage evolution of the proposed hybrid material under tensile loading. In addition, the plain-woven metamaterial has the advantages of simple structure and easy fabrication, which provides a new design idea for the metamaterial radome and important engineering guidance for its fabrication process. [ABSTRACT FROM AUTHOR]