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

Examining Israeli Emergency Medical Preparedness in the Context of Jefferson and Affiliates Practices

Introduction: Recent domestic disasters have demonstrated the challenges and vulnerabilities in the US health care disaster preparedness framework, challenges that extend to Thomas Jefferson University Hospital System (TJUH), in Philadelphia, PA. As Israel serves as a global leader in civilian defense and disaster preparedness, this study examines best practices in response to a mass casualty event at Hadassah Hospital in Jerusalem, Israel, and compares them with existing protocol at TJUH. The list of best practices generated from this research allows for a greater understanding of standards that are feasibly employable at TJUH. Methods: This study examined hospital staff response practices in the event of a mass casualty incident, as informed by Hadassah Hospital data. These practices were compared with TJUH’s Emergency Operations Plan (EOP). TJUH affiliate Christiana Hospital’s EOP was also consulted as a means of comparison to provide additional insight into the feasibility of implementing different emergency response strategies in a US hospital. Based on these data sets, a list of practices from Hadassah Hospital that were judged to be most useful in the face of a mass casualty event and most implementable at TJUH were compiled. Results: Per approval by Dr. James Plumb on 4 December 2019, results for this study are forthcoming and will be added as soon as they are available. Conclusion: Theoretical and practical implications based on the findings will be available as data analysis is completed

Language, education and social development- remembering David Horsburgh

The invitation for an article in Learning Curve came at a time when the subject of Karnataka's “language policy” was in the news once again. For a subject to retain the value of topicality it must reappear in cyclical bursts, make its presence felt aggressively in many directions, exhaust itself, and retire to its quarters until its next appearance. Other topicalities must be given their cyclical turns - nature vs. nurture in intelligence, elimination vs. rehabilitation of street dogs, reservation vs. merit in public institutions and so on. Not too long ago the games and pastimes of children too followed cycles of appearance, with tops, seven stones, kabaddi, kites and gilli danda following the laws of seasonality. One cannot help wondering about the cyclical nature of our engagements. There must be a scientific explanation lying there somewhere, waiting to be discovered

Bridging the great divide - Rediscovering Rabindranath Tagore

Gurudev Rabindranath Tagore, the greatest artist this land has produced, was also a man of deep rational thought and a clear scientic temper. That Albert Einstein, often regarded as the “scientist of the century”, engaged in a discourse with Tagore and unhesitatingly admitted that he came away enlightened says something about the poet’s perspective to art and science

Mechanical Failure Analysis of Needles, for Micro-needle Array Dry-electrodes

 Dry electrodes, which have an array of vertically aligned conducting micro-needles over a conducting substrate/base are most suitable for long-term continuous monitoring of EEG-signal, and overcomesthe disadvantages of conventional wet electrodes. A crucial design requirement for thesemicro-needlearrays, is the choice of the needle material with suitable mechanical strength to penetrate the skin without mechanical failure. This paper gives, the results of mechanical failure analysis of different needle materials that have been typically used/proposed for invasive use. A conical needle with 150μ width at the base and 10μ width at the tip, and length in the range 10μ - 200μ was taken up for calculation. The Critical load for failure, falls in the following descending order for the selected materials: viz., Carbon Nanofibre (CNF), Titanium-alloy (Ti 6-4), Single Crystal Silicon, Nickel, Tungsten, Platinum-Iridium (Pt90 percent-Ir10 percent), Stainless Steel (SS304),Poly Methyl Methacrylate (PMMA), Polyimide, Polycarbonate, Gold, Silver, Photoresist-SU8, Polyurethane and Poly DiMethylSiloxane (PDMS).Taking the most accepted value of 0.1N as the penetration force required for needle penetration into skin, it is seen that for a needle length of 100μ, the following materials, Carbon Nanofibre (CNF), Titanium-alloy (Ti 6-4), Single Crystal Silicon, Nickel, Tungsten, Platinum -Iridium (Pt90 percent-Ir10 percent) andStainless Steel (SS304), can penetrate the skin without mechanical failure

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