An experimental and modeling study is conducted on the vacuum consolidation of commingled glass/thermoplastic composites as part of a larger project on manufacturing large monolithic structures from these precursors. Two polyethylene terephthalate (PET) matrices are employed: semicrystalline PET and an amorphous PET copolymer. Samples of commingled fabric are processed into consolidated composites by means of both a convective oven, as will be used in practice, and a small-scale experimental characterization rig, designed to measure consolidation accurately. The samples are then cooled to room temperature. In this article, the thermal and consolidation characterization of these fabrics is reported. Thermally induced consolidation is observed to occur in two stages: a low temperature solid state de-bulking near to Tg, followed by full melt impregnation at a higher temperature. Both stages are modeled separately using an empirical model based on the Kamal equation. The measured consolidation versus time profiles suggest a rapid impregnation and wetting of the fibers, occurring near to the melting point of the semicrystalline polymer. The PET melting endotherm and crystallization exotherm have little effect on the observed thermal profiles, suggesting that these effects can possibly be neglected when modeling the process.
The focus of this research is to numerically investigate the effect of blade hub line variation on the performance (Total pressure-ratio and Isentropic-Efficiency) of centrifugal compressor from stall to choke to study the operating range and stall margin. An optimization technique is carried out in which the meridional profile hub line is modified and compared with the high Mach number SRV2 compressor designed and fabricated by DLR (German Aerospace Center). Numerical simulations showed significant increase in the stall margin and operating range by bargaining on pressure ratio and isentropic efficiency. Reynolds Averaged Navier Stokes (RANS) based k-ε model is used to predict turbulence using numerical simulations. The value of Y plus for the structured mesh near the boundaries is kept 35. Blade hub line being the important parameter, has substantial performance improvement of centrifugal compressor. The novel design improved the stall margin by 44 percent while operating range from stall to choke has been upgraded by 7.5 percent.
This chapter focuses on the processes in which polyester is usually used for the manufacturing of mechanical components and assemblies. Various methods of manufacturing these products are mentioned in this chapter. These methods include wet layup method, filament winding, pultrusion, vacuum bagging and autoclave curing, resin transfer molding (RTM) and vacuum-assisted resin transfer molding (VARTM). Various production levels and properties can be achieved by polyester resin using abovementioned processes. Each process has its own benefits and disadvantages, which are discussed in this chapter. Furthermore, the use of polyester in making electrical insulation is also discussed in the chapter. Advantages and disadvantages of each impregnation technique are also explained.
This paper describes the development of a thermoplastic composite system for structural application in the chassis of an electrically propelled bus. The work involved the characterisation and modelling of a vacuum bag moulding process using a woven commingled thermoplastic composite precursor. The matrix materials were PET and a PET copolymer. The process employs an ambient pressure oven, with tooling that can be made from composite, metal or ceramic. The process results in good quality laminates, with a void content generally lower than 1%. The temperature pro le through the part and the consolidation behaviour were characterised and modelled. It was found that the thermal pro le could be modelled with adequate accuracy using 'single point' values of thermal properties. Experimental measurements showed, for the rst time, that consolidation occurs in two stages: a low temperature solid state debulking near to T g , followed by full melt impregnation at a higher temperature (above T m in the case of the homopolymer). Both stages in the consolidation process were modelled separately using a simpli ed version of the Kamal equation.PRC/1818 INTRODUCTIONHowever, for medium volume production runs of This project involved the development and characterlarger parts, polymer composite tooling oVers many isation of a vacuum bag process for the manufacture attractions, including the ease with which doubly of thermoplastic composite parts on a size and scale curved shapes can be produced. Moreover, improved suitable for lightweight public transport vehicles. The resin chemistry has resulted in composite tooling with study centred on the replacement of load bearing signi cantly improved high temperature capability. chassis components of the electric bus shown in Fig. 1.In the present project, glass-cyanate ester tools were One of the challenges of the project was the use of supplied by ACG of Heanor, UK. These were found tooling made from a composite with a polymeric to work well with the PET copolymer for repeated matrix. This posed some problems due to the high mouldings. processing temperatures (in the range 200-300°C),The bene ts of using thermoplastic composite which limited the range of tooling materials that technology1-5 include emission free processing and could be used. Of course metal tooling may be recyclability of both intermediate factory scrap and nal employed for this application, and certain ceramic product. Since both the homopolymer and the based materials1 have also been found to be viable. copolymer used in the present study are derivatives of PET, the starting material can, in principle, be derived from the established PET recyclate stream. The availability of a lightweight thermoplastic composite will also promote the use of energy eYcient transport. Thermoplastic composites have been investigated for several transport applications, but attention to date has focused mainly on polypropylene (PP) matrixes.2 This has occurred mainly because PP composites are the most generally available thermoplastic compos...
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