Designing of wound composite structure for high pressure composite vessels by table method
Wojciech Błażejewski
Quarterly No. 2, 2010 pages 154-158
DOI:
keywords: fibre winding, filament winding, table method, fibre architecture designing, interweaving, fibre crossovers lines, wound structures, high pressure composite vessel
abstract High strength/weight ratio is one of the most important advantage of GFR applications. It is also true for the case of high pressure composite vessels used for storage of compressed gases like natural gas (CNG) and compressed hydrogen (CH2). The composite layers for composite high pressure vessels are commonly produced by winding of resin impregnated continuos fibre bundles on metallic or plastic cylinders (liner). Fibre bundle architecture in wound composite layers is closely connected with vessel mechanical properties. The winding manufacturing process introduce into wound composite materials some species like fibre crossovers and interweavings, fibre undulations and „rich” resin localisations. These are known to be localizations where usually damage initiation start. Thus fibre architecture designing is one of the most important step. The new fibre architecture design method (table method) has been here presented. This method allows easier designing of wound structure and consumes lees time and object number. Forty high pressure composite vessels with 8 possible fibre architectures (according to table method) have been made by winding of epoxy resin impregnated continuous glass fibre on 114 mm diameter metallic liners (10 l volume) at ±55° winding angle. The strains (in the interweaving arrangement region - ”interweaving lines” LP and in the free interweaving region at 27.5 MPa internal pressure), voids and total interweaving amounts in 8 wound structures have been given. It was found that the strains in the free interweaving region decrease with the increase in the total interweaving number, but the strains in the interweaving arrangement regions behave in opposite way. The strains in both regions become very close to each other for high amount of interweavings and small interweaving arrangement. It was also found that scatters for both measured strains increase from 5 to 20% for 131 and 580 total interweaving amounts, respectively. One may conclude that damage process in high pressure composite vessels at 27.5 MPa internal pressure is more far gone when the wound fibre architectures have high total interweaving amounts and interweaving arrangement regions are small. It also seems that designer of wound fibre architectures for internal pressure load applications should choice ones with minimum interweaving amount and high arrangement region.