High-performance Fiber Composites Research Articles

New simple strategy for improving interfacial adhesion of basalt fiber composites by adhering bio-based β-cyclodextrin on fiber

Though basalt fiber has excellent mechanical properties and attractive green feature, the ultralow interfacial strength of fiber-to-polymer greatly limits its application. Herein, investigation into the first use of β-cyclodextrin (β-CD) and silane coupling agent as surface modifier for basalt fiber by dint of chemical grafting strategy was presented. The resulted fiber was discovered to provide the growth of 61.5% in fiber-to-epoxy adhesion relative to untreated basalt fibers in epoxy. The change in interfacial strength is associated with the improved epoxy wetting behavior and increased covalent interactions contributed by the unique conical hollow ring architecture of β-CD that offers more acting sites to be linked and accommodated with more silane coupling agents for subsequent chemical crosslinking and physical entanglement with greater epoxy molecules. Additionally, the crack deflection by “rigid” β-CD at interphase dissipates more energy. First proved superiority of β-CD for strengthening the interphase in this work paves the way for developing green and high-performance fiber composites, responding well to the sustainable development in engineering.

Synergistic interfacial effects of sizing agent containing gradient curing agent and pre-heating treated carbon fibers

This investigation focuses on the use of sizing agent containing gradient curing agent from two directions for carbon fibers coupled with pre-heating treatment before fibers combined into composites to improve interfacial adhesion. Growth in interfacial shear strength (IFSS) up to 92.4 % was noticed for fibers functionalized with sizing agent of high-to-low curing agent from fiber-to-resin (CFH→L), relative to control fibers. This is related to the greatly enhanced interactions at both fiber/sizing and sizing/resin interfaces accompanied by increased interfacial curing degree that generate a stronger interphase. Further optimization of 4.1 % increase in IFSS was achieved for CFH→L via pre-heating treatment before being composites, while larger IFSS increment of 16.7 % after pre-heating treatment was observed for fibers coated with sizing agent of low-to-high curing agent from fiber-to-resin (CFL→H). This reveals that pre-heating is more effective for fiber that has weaker interactions with sizing agent. This work is believed to be a preliminary but crucial trial toward obtaining high-performance fiber composites by simply applying it in the already existed fiber production line.

Structural modeling and analysis of three-dimensional cross-linked braided preforms

Abstract Rotary braiding is widely used in the preparation of high-performance fiber composites. However, neither conventional rotary two-dimensional braiding nor rotary three-dimensional braiding can prepare three-dimensional preforms with low porosity and dense surface yarns. This article designs a three-dimensional cross-linked braiding equipment, describes the mechanism of carrier motion of three-dimensional cross-linked braiding, and obtains a numerical model of three-dimensional cross-linked braided preforms by establishing the spatial coordinate system of the braided chassis and using cubic B-spline curve fitting. The reasons for the large difference between the numerical model of preform and the real fabric are analyzed, and an optimization algorithm is proposed to make the fabric compact by gathering the yarn to the center of the fabric. The experimental samples are braided on a three-dimensional cross-linked braiding machine, and the reliability of the optimization algorithm is verified by comparing the yarn coordinates of the experimental samples with those of the optimized numerical model. The accurate establishment of the geometric model of the preform provides a solid foundation for carrying out the prediction of the mechanical properties of composite materials.

Simulation method of debris cloud from fiber-reinforced composite shield under hypervelocity impact

A Whipple shield is a double-plate structure commonly used to protect spacecraft from space fragments. The space fragments hit the outer plate and break into a debris cloud with dispersed energy and momentum, which reduces their risk of penetrating the bulkhead. With the development of high-performance materials, for example, high-performance fiber composites, traditional Whipple shields have evolved into advanced complex shields. Using the finite element and smoothed-particle hydrodynamics adaptive method and mesoscopic modeling technology, this study aims to establish a numerical model for fiber-reinforced composite shields under hypervelocity impact. Several mesoscale models for fiber-reinforced composites for problems under hypervelocity impact have been established. These models can be meshed with high-quality elements that satisfy aerospace engineering requirements (identify hazardous fragments in the debris cloud) while retaining the main structural features of materials. We established a numerical model by combining the finite element and smoothed-particle hydrodynamics adaptive method and existent mesoscale models. Using laminates, 2D woven fiber-reinforced plastics, and 3D woven fiber-reinforced composites as examples, numerical simulations of the debris cloud generated by an aluminum ball under hypervelocity impact were conducted. The simulation results, which are highly consistent with the experimental results of the debris cloud shape, accurately reflect the failure features of laminates, that is, fiber fracture and delamination. Simulation results show that the fiber-reinforced composite has better protection than the aluminum plate at the same areal density. By comparing the debris clouds generated by the hypervelocity impact on different fiber-reinforced composite shields, it can be argued that composite knit modes strongly affect the protective effect of fiber-reinforced composites. This work shows that the simulation method combining the finite element and smoothed-particle hydrodynamics adaptive method and mesoscopic modeling is a powerful tool for simulating the Whipple shield with a fiber-reinforced composite. More importantly, this method can also be applied to other Whipple shields with complex structures and advanced materials, for example, other composite materials, metal foam materials, and multilayer board protective structures.

Cure kinetics and rheology modelling of boehmite (AlOOH) nanoparticle modified epoxy resin systems

Nanoparticles can effectively increase the resin matrix properties, which is especially attractive for fabrication of high-performance fiber composites by liquid composite molding (LCM) processes. However, the cure kinetics and rheological behavior of the matrix, which are the most critical aspects in LCM processes, could be affected by the introduction of nanoparticles, depending on the surface functionalization and concentration. In this paper, the cure kinetics and rheology of a boehmite nanoparticle modified epoxy matrix is characterized and modelled. The influence of boehmite nanoparticles on cure and rheological behaviors is analyzed. By optimization of the regression method combined with model parameter analysis, a good correlation between the model parameters and nanoparticle concentration is determined. Finally, a generalized model is put forward to describe and predict the cure kinetics and rheology depending on time, temperature, and concentration of nanoparticles.

High Performance Fiber Composites with Enhanced Energy Absorption for Underground Construction

In order to provide higher energy absorption capacity in fiber reinforced composites, it is normally required to use more volumes of fibers. This leads to economical limitations as the fiber content usually controls the cost of the composite mix. This research has tried to enhance the energy absorption capacity of the composite while keeping the fiber content constant or at the minimum possible value. A series of laboratory tests were conducted in Iran and Turkey with the same material and fiber type and some recommendations for achieving the optimized results were proposed. Beam and panel tests were used to account for the energy absorption and the results were used for tunnel lining design.

An empirical fatigue-life model for high-performance fibre composites with and without impact damage

Abstract This article follows earlier work on the development of a life-prediction method for carbon-fibre/epoxy laminates. For comparison with the behaviour of a number of different CFRP laminates already studied, further constant-life fatigue data have now been obtained for a further CFRP composite and a GRP laminate of similar construction – a 16-ply [(±45,0 2 ) 2 ] S lay-up. Fatigue tests have been carried out on these materials in both the virgin condition and after damage by low-velocity impacts. Following analysis of these new data and a re-examination of the older data base, the constant-life model has been appropriately modified. It now offers a prediction procedure for the fatigue response of composite materials in the virgin and impact-damaged conditions which requires, in the first instance, only the tensile and compressive strengths of the composite in question. The model is equally applicable to both GRP and CFRP, despite the fact that the fatigue response of a GRP laminate is different from that of an equivalent CFRP material.

Reliability of high performance fibre composites

Over the last decade, reinforcement made of fibre reinforced plastics has emerged as an alternative to steel reinforcement in concrete subject to aggressive environments. The high rupture strengths of these new materials allied with other attractive properties make them particularly interesting as prestressing tendons. In such applications the reliability has to be satisfactory not only in the prestressing operation but during actual use. This makes it necessary to have a material characterization where both the short term and the long term material responses are considered.

High Performance Fiber Composites with Special Emphasis on the Interface A Review of the Literature

Revue bibliographique de 102 references sur les proprietes de fibres de verre, carbone, aramide, fibres haut module et hybrides, des matrices thermoplastiques ou thermodurcissable, mise en œuvre, proprietes de plastiques renforces avec etude de l'influence du diametre, de la longueur, du volume, de l'orientation des fibres, des especes vides, et des phenomenes a l'interface fibre-matrice

The internal pressure, mechanical properties, and water absorption of carbon fibre composites with spiro-epoxy copolymer matrices

High-performance fibre composites embodying a new principle have been manufactured and tested. In these composites the polymer matrix exerts a controlled pressure on the fibres. Although some pressure between fibres and matrix is necessary to permit the transfer of loads, the pressure normally present (about 40–50 M Pa) is much in excess of what is needed for carbon fibre composites (roughly 10 M Pa). This leads to undesirably high internal stresses, and is a primary cause of the low Izod impact strength of these composites, as compared with glass fibre composites. A four-year investigation of carbon fibre reinforced epoxies has shown that spiro orthocarbonate monomers, copolymerized with the epoxy, can reduce shrinkage pressures by nearly 70%, and increase the impact strength by about the same amount. At the same time fatigue life is improved. No important change in other mechanical properties is observed, and the water resistance of the composite is increased slightly.

The Relation Between the Network Structure, Deformation and Failure Processes, and Mechanical Properties of Epoxies

The increasing use of high-performance fiber composites in critical structural applications has led to a need to predict the lifetimes of these materials in service environments. Such predictions require a basic understanding of (1) the microscopic deformation and failure processes of the composite, (2) the roles played by the fiber, epoxy matrix, and fiber-matrix interface in composite performance, and (3) the relations between the structure, the deformation and failure processes, and the mechanical response of these three elements and how those relations are modified by environmental factors.

The Relation Between Physical Structure and Deformation and Failure Processes of Kevlar 49 Fibers

To conserve energy, high-performance fiber composites are increasingly used by the transportation industry as lightweight, strong structural materials. In the past, graphite, glass, or boron fibers were predominantly used in these composites. However, since their introduction ten years ago, poly(p-phenylene terephthalamide) (PPTA) fibers (Kevlar 49, E. I. du Pont) have found increasing use in such composites. The chemical structure of PPTA is illustrated in Fig. 1. The PPTA macromolecule has the physical shape of a rod and an average length of ∼200 nm.

High performance fiber composites: Lovelace, A. M. Materials Research and Standards, Vol 11, No 5, pp 8–10 (May 1971)

High performance fiber composites: Lovelace, A. M. Materials Research and Standards, Vol 11, No 5, pp 8–10 (May 1971)