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

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

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

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

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

Behaviour of ultrasonic velocities in amorphous Se<SUB>90</SUB>Ge<SUB>10</SUB> and Se<SUB>85</SUB>Ge<SUB>15</SUB> alloys near their glass transition

Precise measurements of 10 MHz frequency longitudinal and shear wave velocities are reported in amorphous SeGe alloys near their glass transition temperature Tg . There is a sharp decrease of the velocities near Tg , but the reduction in velocities appears smaller than expected

Effect of hydraulic coefficient on membrane performance for rejection of emerging contaminants

The efficient removal of Endocrine Disruptive Chemicals (EDCs) namely oxybenzone and atrazine using polysulfone (PSf) composite membranes is reported in this article. A negatively charged hydrophilic mixed matrix membrane was prepared by using Polyaniline modified halloysite nanotubes (PANi-HNT) and polysulfone. The X-ray diffraction (XRD) and attenuated total reflectance infrared (ATR-IR) technique confirm the conversion of Halloysite nanotubes to Polyaniline modified halloysite nanotubes and their presence in membrane matrix. The microvoids observable in the SEM images depict the internal structure of the membrane. Further, increasing in the water uptake and decreasing in the contact angle with respect to increasing the concentration of Polyaniline modified halloysite nanotubes confirm the enhancement of the membrane hydrophilicity. This hydrophilicity increases for higher concentrations of PANi-HNT leads to a significant improvement of the water flux. The removal efficiency of prepared mixed matrix membranes was found to be 98% for oxybenzone and 50% for atrazine. The separation process was discussed in terms of adsorption coefficient, membrane charge and mean pore size. Considering the performances highlighted in this study, the proposed membranes appear usable for the removal of EDCs from contaminated solutions

Assessment of Anti-aging Efficacy of the Master Antioxidant Glutathione

A chief tripeptide antioxidant Glutathione (GSH) is present inside each body cell which may have a profound effect in the control of aging. The anti-aging potency of GSH and its role towards the progression of certain age-related disease is still unclear. Glutathione based articles were searched on PubMEd database since the very first study of glutathione related to its discovery in 1923 to its present status till 2016. The data was made more informative and precise by searching glutathione relevant reports on google. Those articles were selected which were indicating the association of glutathione with the progression of age-related diseases, pre-clinical and clinical studies and age-longevity effect. It was analyzed that the increased oxidative stress (elevated GSSG/GSH ratio) is responsible for the incidence of age-related diseases and different organs failure. The glutathione redox ratio (GSSG/GSH) was found to be more pro-oxidizing with aging which plays a chief role for the generation of reactive oxygen species (ROS) and subsequently damages the macromolecular structures affecting the normal body mechanisms and functions. The clinical data has recommended that glutathione is a potent therapeutic agent for the control of age-related diseases and experimental analysis has confirmed its prominent effect in age-longevity