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

Experimental Comparison Of Seasonal Performance In R410A Chiller Using Single Speed And Two Stage Compressor

Rising cooling needs for the residential and commercial air conditioning sectors and the requirement of higher SEER values increased the focus on energy-efficient part load performance. Although several studies exist on the topic of capacity modulation, there is no comprehensive study that compares different modulation strategies in the same experimental facility. In a first step, this paper aims to experimentally compare two different capacity controls for scroll compressors (single speed vs two-stage compressor) using the same R410A water ethylene glycol (WEG) chiller having a nominal cooling capacity of 8kW. The tests were conducted according to AHRI Standard 551/591 (2018). The Integrated Part Load Value (IPLV.SI) was used to fairly compare all these capacity modulation strategies. Based on the experimental results, the difference in the order of 8% in IPLV.SI is found. While both compressors showed comparable capacities and COPs at the higher modulation conditions, two stage compressor has better COP at the lower condition because of its ability to operate at a lower stage and better meet the required load

Antibiograms of Commensal Escherichia Coli Isolated from Cattle in Some Selected Commercial Farms in Jos South Plateau State, Nigeria

Antimicrobials are used for livestock production in the control and treatment of infections and as growth promoters but has been abusively used over the counter in middle and low income countries where access to these drugs are met with minimal restrictions and prescriptions. Escherichia coli (E. coli) is a normal inhabitant of the gastrointestinal tract of animals and a major reservoir of antibiotic resistant genes. The study aimed to identify antimicrobial resistance (AMR) phenotypes of commensal E. coli isolated from cattle in Jos South Local Government Area (LGA) of Plateau State Nigeria. Forty eight (48) fecal samples were collected from cattle in four randomly selected commercial farms, screened for E. coli, confirmed by conventional PCR and antimicrobial resistant profiles were determined using ten (10) commercial prepared antibiotic discs. Conventional PCR confirmed seven (7) isolates of E. coli equivalent to 14.58 % prevalence. The isolates showed varied phenotypic resistance to six antimicrobials, with a 100 % resistance to Reflacin (10 mm), Ceporex (10 mm) and Nalidix acid (10 mm). Thus, the findings of this study suggests the possibility of an extensive use of cephalosporin among farmers in the study area. The need for a larger implementation of surveillance programme in order to reduce and curb the spread of AMR determinant was recommended

Experimental Characterisation of GLass Aluminum REinforced (GLARE™) laminates

Fibre metal laminates such as GLARE™ have found promising application in the aerospace industry. These laminates were developed at the structures and materials laboratory of Delft University of Technology, Netherlands. GLARE™ is a material belonging to the family of Fibre Metal Laminates consisting of thin aluminum layers bonded with unidirectional S2-Glass fibres with an adhesive. Aluminum and S2-Glass when combined as a hybrid material can provide best features of the both metals and composites. These materials have excellent fatigue, impact and damage tolerance characteristics and a lower density compared to aluminum. GLARE™ has found major application in front and aft upper fuselage, leading edges of empennages of advanced civil aircrafts like A380. This document looks into the evaluation of two configuration of GLARE™ for its mechanical and impact characteristics. The mechanical characterisation was carried out for tensile, compression, Flexure, ILSS, Open Hole Tension, Open Hole Compression and Shear (Iosipescu). The impact behaviour were characterised based on a low velocity drop weight impact carried on these laminates. The study shows that the basic properties evaluated were more dictated by the property of the S2-Glass used. The studies show that GLARE™ laminates posses’ high impact damage resistance compared to other composite material. All the test datas generated for this study will be brought out in this document

Development of 3D Angle-Interlock Woven Preforms for Composites

The advent of three dimensional (3D) reinforcements has been mainly to overcome the issue of delamination and improve upon the damage tolerance properties by introducing fibres in the thickness direction for advanced composite applications. 3D preforms can be developed using various techniques. Angle-interlock weaving is one of them. This paper details about the efforts being put at CSIR-NAL for developing angle-interlock woven preforms. Four types of angle-interlock structures viz., layer-to-layer and through thickness (both with and without stuffer yarns) were developed using 6K, 400 Tex TC-33 grade Carbon tows on a custom designed handloom. The preforms without stuffer yarns had 4 layers of warp and were of 1.5± 0.2 mm thick. Preforms with stuffer yarns had 6 layers of warp (including 2 stuffer yarn layers) and were of 2.3±0.1 mm thick. Thermoset composites were prepared from these preforms using EPOLAM 2063 (an epoxy based resin system) by RTM process. The fibre weight fraction for these composites ranged from 0.53 to 0.58 and they were subjected to mechanical tests such as tensile, flexural and interlaminar shear strength. Test results showed improved response (in the warp direction) with respect to shear properties while the tensile and flexural properties were equivalent to that of the plain woven composites

Kožna mijaza u pasa uzrokovana kukcem Cordylobia antropophaga u Josu glavnom gradu pokrajine Plateau u Nigeriji

One hundred and ninety (190) dogs infested with myiasis, presented to veterinary clinics in the Jos metropolis and surroundings of Plateau State, Nigeria, were screened to identify the fly species responsible for the infestation. The age, breed and sex prevalence of the dogs were also evaluated. All 957 (100%) larvae extracted from the dogs were those of Cordylobia anthropophaga. Of the infested dogs, 58.95% were females, with a mean intensity of 4.62 larvae/female; a statistical difference (P<0.05) was observed between the sexes, while younger dogs were infested with more larvae than older dogs. All the breeds of dogs evaluated were infested to varying degrees. The public health significance of these findings was discussed.Istraživanje je provedeno na 190 pasa u kojih je dijagnosticirana mijaza u sklopu različitih veterinarskih klinika u Josu te ostalim područjima pokrajine Plateau u Nigeriji s ciljem utvrđivanja uzročnika. Vrednovana je i predispozicija s obzirom na dob, pasminu i spol. Svih 957 izdvojenih ličinki (100%) pripadalo je vrsti Cordylobia anthropophaga. Od ukupnog broja infestiranih, 58,95% su bile ženke s prosječno 4,62 larve. Dokazana je statistička razlika u invadiranosti među spolovima (P<0,05). U mlađih pasa je pronađeno više larvi. Stupanj invadiranosti bio je različit u različitih pasmina pasa. U radu je raspravljena važnost rezultata za javno zdravstvo i opasnost za ljude

3D WEAVING POSSIBILITIES ON AN 8 SHAFT LOOM

This work’s focus is towards exploring the possibilities of weaving select type of 3D reinforcements on the commercially available 2D weaving looms of the textile industry. In this context, two classes of 3D reinforcements were developed using 6K Carbon rovings of 400 Texon an 8 shaft handloom. The first class comprised of weaving single layer profiles wherein, ‘T’and ‘p’ profiles were woven. The second class comprised of weaving planar multilayer (angle interlock structure) samples of two types viz., layer to layer and through-thickness. In this class, a ‘T’ profile was also woven. Weave Design Plan for these structures were developed using the warp(for single layer profiles) and weft ( for angle interlock structures) yarn cross-sections. It has finally been inferred that, woven cloth construction design and 2D weaving technology can be successfully utilized to develop select class of 3D reinforcements for composite applications

Knitted Preforms for Composite Application

Knitted structures occupy a special position in composite preforming due to their inimitable characteristics. An insight into the knitted structures with respect to their composite preforming characteristics is presented in this article. Directionality of knitted structures and requirements of high performance fibers for knitting have been discussed. Contourability, net-shape preforming, high dynamic mechanical properties along with easy and rapid manufacturability are the important features of knitted structures to match the composite preform requirements. In this article, the work done in the above areas of research have been critically reviewed