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The strength prediction of fiber-reinforced polymer (FRP) cables provides a non-destructive technique for evaluating the cable properties. In this study, a shear-lag model that assumes impregnated fiber bundle (IFB) and resin matrix as the basic elements is proposed and complemented in finite element (FE) models. By importing the strength distribution of IFB fitted from experiments, the effectiveness of the proposed model was validated for four types of basalt FRP single tendons. The simulated strength demonstrated high accuracy with an error of less than 6%, which was more reliable than conventional methods. The full-scale failure mechanism and damage process of FRP cable can be explained from the aspect of IFB element, which is different from filament-based models. The effect of fiber strength randomness and the contribution of sheared resin matrix could be quantified. Then, a multiscale evaluation of basalt FRP cable was carried out, and the different failure patterns of the tendon and cable were identified. Based on the other external data of carbon FRP cable, the simulated cable force was found to be in better agreement with experimental one, compared to directly taking a strength reduction on the total tendon force.

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.

The interfacial interaction between carbon fibers (CFs) and resin matrix is an important factor affecting mechanical performances of CF-based composites. In this work, a new approach combining electrodeposition method (EDM) and “Ag–S″ bonds was applied to fabricate functional CF-based composites while preserving the mechanical properties of CFs. Silver nanoparticles were first attached on the CF surface by EDM. Then 4-aminothiophenol or 4-mercaptobenzoic acid was linked to Ag surface by Ag–S bonds to incorporate different functional groups onto the fiber surface. The interfacial shear strength was improved pronouncedly while the tensile strength was maintained consistent. The interfacial shear strength of the CFs after functionalized was increased 21.10% and 32.04%, respectively. However, the tensile strength of them decreased no more than 3%. With improved properties, these nanocomposites have potential applications for aerospace, transportation, electronics and other fields.

This paper examines the effect of through-thickness stitching on the in-plane fatigue performance and fatigue damage mechanisms of a glass-reinforced polymer (GRP) laminate under zero-to-tension cyclic loading. The influence of stitching orientation and stitching density on the S-N curve of the laminate has also been investigated. The fatigue resistance was reduced considerably by stitching, particularly at relatively low fatigue stresses. Both the non-stitched and stitched laminates experienced similar types of fatigue damage, i.e. cracking of the vinyl ester resin matrix and glass fibres, and debonding between the matrix and fibres. However, the stitched laminates also suffered fatigue failure between the stitches and surrounding laminate, which contributed to the reduction in the fatigue lives of these materials. Their fatigue resistance was also reduced by damage to the glass fibres caused when the laminates were stitched. It was concluded that while stitching improved the interlaminar fracture properties of the GRP, it seriously degraded the fatigue performance.

A micromechanical analysis is proposed for the determination of the overall response of unidirectional composites with non-linearly viscoelastic resins. The non-linear behavior is modeled by the single-integral constitutive equations developed by Schapery. The method is implemented for the prediction of the non-linear viscoelastic behavior of unidirectional glass/epoxy and graphite/epoxy composites subjected to various types of loading conditions. The predicted response is compared with a finite element solution, and good agreement between the two methods is shown to exist.

Various continuous filament cores helically wrapped with a paper tape have been produced for use in yarn reinforced composites. Yarn cross-sections showed that the wrap is subjected to large longitudinal and lateral strains when it is substantially overlapped. Core pull-out behaviour when the yarns were embedded in a resin matrix indicated that in some cases the wrap was able to behave in a helical rather than a tubular manner and so increase the resistance to pull-out.

A micromechanical analysis is given for the prediction of the viscoelastic response of resin matrix composites. The matrix is condidered as a viscoelastic material with temperature-dependent properties, and is modeled as a thermo-rheologically complex solid. The method is implemented for the determination of the response of a unidirectional carbon/epoxy composite subjected to various types of mechanical and/or thermal loadings. The reliability of the prediction is checked by comparison with a numerical solution, and good agreement is shown to exist in most cases.