3D Preforming technologies for composite applications

With the high end applications like aerospace, the orientation of the fibrous reinforcement is becoming more and more important from load bearing point of view as well as need of placing the reinforcement oriented in the third dimension. In textile process, there is direct control over fiber placements and ease of handling of fibers. Textile technology is of particular importance in the context of improving certain properties of composites like inter-laminar shear and damage tolerance apart from reducing the cost of manufacturing. Depending upon textile preforming method the range of fiber orientation and fiber volume fraction of preform will vary, subsequently affecting matrix infiltration and consolidation. As a route to mass production of textile composites, the production speed, material handling and material design flexibility are major factors responsible for selection of textile reinforcement production. This article reviews the developments occurred in this field of textile preforming along with their advantages and disadvantages and also presents the studies on 3D multilayer interlocked woven reinforced composite materials performance

Cyclic bursting loading on needle-punched nonwovens: Part I – Distention behavior

The present study aims at examining different needle-punched polypropylene nonwovens under different cyclic bursting pressure. Various fabric parameters including mass density, punch density and fibre fineness have been investigated. For the cyclic test, the distension is measured at different cyclic bursting pressures proportionate to the bursting strength of the fabric. Other parameters including the cyclic pressure magnitude, the number of cycles, and the rest time at peak pressure have also been investigated. It has been found that the bursting strength and distension of fabric increase with an increase in mass density, while they show opposite trend with punch density and fibre denier (p < 0.01). The distension value of each sample increases with an increase in the cyclic parameters i.e. number of loading cycle, rest time and pressure peak

Water filtration using nonwoven cartridge filter system

A cartridge based fibrous filtration system has been designed and investigated. For the fibrous medium, needle-punch nonwoven structure has been selected and different nonwoven samples are analysed for the water purification. A series of different needle-punched nonwovens made of polypropylene have been produced by changing mass per unit area, needling density and fibre linear density. A chemical oxygen demand test has been employed to obtain the filtration efficiency (FE). The FE obtained for these samples ranges from 8.84% to 78.04% in purifying the reference water (mud water). It has been found that the FE increases with increase in mass per unit area and needling density (p < 0.01). Also, the filter media made of finer fibres displays higher FE than coarser fibre (p < 0.01). On examining the filter performance in multiple filtration cycles, it is found that the FE increases initially and finally reaches to a saturation value. A good correlation (r2 > 0.95) has been found for the FE of each cycle with the air permeability, thickness and weight density of the loaded filter. The FE of the bare nonwoven (maximum FE) further improves (95%) by incorporating activated particles

Multilayer interlocked woven fabrics: simulation of RTM mold filling operation with preform permeability properties

The simulation of resin flow during the resin transfer molding (RTM) process through multilayered textile fabric of known permeability and porosity has been attempted in this study. A simple three-dimensional computational fluid dynamics (CFD) simulation model has been developed and the results of the simulation are compared with the experimental RTM resin flow through multilayer interlocked woven structures. A multiphase simulation model is observed to reasonably predict the time for RTM mold filling. Fabric structural influence in terms of an Interlacement Index (I) has significant influence on the resin flow behaviour of the multilayered preform. A higher I of the preform means a longer time to fill the mold in both the experimental and simulated results. Images of the simulated flow front has been compared with the experimental results and it is observed that not only the mold filling time, but also the area of resin flow in the multilayer perform, is influenced by a fabric structural factor, I.(undefined

Compression and permeability properties of multiaxial warp-knit preforms

Textile preform properties such as compression and permeability greatly influence the quality of the composite material and its performance, particularly those prepared by injection moulding techniques like resin transfer moulding (RTM). Directionally oriented warp-knit biaxial, triaxial and quadraxial glass fabrics have been studied for these preform properties. The preform compression properties were tested on the universal testing machine up to a maximum force of 250 N. The rate of test liquid flow through these preforms has been measured using the horizontalwicking test method. The permeability of these preforms has been analyzed based on the liquid flow-rate data. Fibre orientation and fibre volume fraction of the preforms are observed to be important factors influencing these preform properties

Study of cyclic bursting loading on needle-punched nonwovens: Part II – Change in air permeability and compression behavior

Efforts have been made to investigate the physical properties of needle-punched nonwovens, such as compression and air permeability, before and after the application of cyclic bursting pressure. It is observed that the structural parameters, such as areal density, needling density and fibre fineness, have significant effect on the aforementioned fabric characteristics. More compression is observed in a sample with low mass density. Sample made of coarser fibre shows lower compression as compared to finer fibre samples. The air permeability decreases with increase in mass density. On conducting cyclic bursting test on a sample, the values of air permeability and compression change significantly. The cyclic parameters, such as pressure magnitude and rest time at cyclic peak pressure, cause significant structural changes and reorientation of the fibre during deformation. Increase in pressure and rest time causes increase in compression parameter (α) and air permeability. Nevertheless, at low cyclic pressure level (10% of bursting pressure), the network becomes compact due to fibrous reorientation, and therefore both the values of compression parameter (α) and air permeability show initial drop. On examining the samples made of coarser and finer fibres, the variation is observed in the extent of change in the air permeability

Influence of preform interlacement on the low velocity impact behavior of multilayer textile composites

Impact property of composite material is influenced not only by the type of fiber/matrix, but also by the woven structure of the reinforcement. Presence of 3D fibers in reinforcement is reported to enhance the performance of textile composites in an impact event. This article attempts to study the influence of interlacements in the multilayer woven interlocked 3D structures on the impact properties of the composite material reinforced with them. Low velocity impact testing was carried out on an instrumented drop weight impact tester to obtain loadelongation- time plots of the impact event. It has been observed that increased interlacement in the structure improves the impact resistance of the multilayer textile composites. Further, damage area maps have been developed to understand and analyze the interlacement effect on the impact behavior

Water filtration using nonwoven cartridge filter system

72-79A cartridge based fibrous filtration system has been designed and investigated. For the fibrous medium, needle-punch nonwoven structure has been selected and different nonwoven samples are analysed for the water purification. A series of different needle-punched nonwovens made of polypropylene have been produced by changing mass per unit area, needling density and fibre linear density. A chemical oxygen demand test has been employed to obtain the filtration efficiency (FE). The FE obtained for these samples ranges from 8.84% to 78.04% in purifying the reference water (mud water). It has been found that the FE increases with increase in mass per unit area and needling density (p r2 > 0.95) has been found for the FE of each cycle with the air permeability, thickness and weight density of the loaded filter. The FE of the bare nonwoven (maximum FE) further improves (95%) by incorporating activated particles

Studies on preform properties of multilayer interlocked woven structures using fabric geometrical factors

Structure property correlation is a critical textile research area explored by various researchers and many factors have been proposed over the years to predict/compare/design the woven fabrics. Cross-over firmness factor (CFF) and floating yarn factor (FYF) have been recently proposed as parameters to understand weave effect on fabric properties (Morino, H., Matsudaira, M. and Furutani, M. (2005). Predicting Mechanical Properties and Hand Values from the Parameters of Weave Structures, Textile Research Journal, 75(3): 252—257). Redefined CFF and FYF factors using fabric fields in terms of interlacement index (I) and float index (F), respectively have been proposed in this article. This new approach provides better understanding of the interlacements and floats in the woven structure and further they are applied on multilayer interlocked fabrics to quantify the structural influence on the properties. Multilayer interlocked woven fabrics with different interlacement patterns have been developed. Influence of fabric structure on preform properties relevant for resin transfer molding composite manufacture, such as compression, permeability, and tensile behavior were studied with respect to the interlacement and float indices. Tensile and compression tests were conducted on universal testing machine. Liquid permeability of these structures was evaluated based on horizontal wicking and contact angle wettability tests. Results show that influence of structural factor is greater on tensile and permeability properties than the compression properties of these multilayer fabricsThis work has been conducted within the Asia-Link Programme RPO1736, project no IN/ASIA-LINK/002 (82158). The authors wish to thank the European Commission for awarding research programme under the EU Asia-link project to the University of Minho (Portugal) and Indian Institute of Technology-Delhi (New Delhi, India)

Tribological properties of the directionally oriented warp knit GFRP composites

Recently, directionally oriented warp knit structures have gained prominence as reinforcements in composite materials due to their superior isotropic behaviour compared to other types of textile reinforcements. In the present study, composites prepared from four types of directionally oriented warp knit glass preforms with three different thermoset resins have been considered for the tribological characterisation. The tribological tests have been conducted on a reciprocating sliding test rig with ball-on-plate configuration. The tests were conducted in dry (unlubricated) and wet (aqueous) conditions at a fixed applied load (100 N) by varying the sliding distance. E-glass warp knitted preforms were used for the study including biaxial, biaxial non-woven, triaxial and quadraxial fabrics. The matrices were three different thermoset resins namely polyester, vinyl ester and epoxy resin. 13 14 15 16 17 18 19 The main aim of the study was to identify a composite having the best tribological performance, with regard to types of preform and matrix resin. Moreover, the results obtained from the tests have been used to develop a wastage map for these composites, as a function of sliding distance and type of preform in order to have a clear understanding of the tribological process.Fundação para a Ciência e a Tecnologia (FCT