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Abstract
Periodic changes in the material properties of egg shaped profile filament wound fibreglass reinforced unsaturated polyester composite sewer liner pipes were investigated around the perimeter of the cross-section that has constant radii of curvatures in certain sections. On the basis of numerous test results and geometrical and mechanical models of the problem, linear relationships were set up between the origin of the specimens around the section and the density or fibre volume fraction of the material. The inverse proportion between the packing forces (perpendicular to the pipe wall) and the local radii of curvatures means that besides constant fibre tension, higher packing forces appear at the lower radii areas of the section, more matrix material is compressed out of the fibre bundles and the density or the fibre volume fraction becomes higher than in the higher radius areas.
Publication of results was supported by the Hungarian Ministry of Economics through grant no. GVOP-2004-3·1·1. This work is connected to the scientific programme of the ‘Development of quality-oriented and harmonized R+D+I strategy and functional model at BME’ project. This project is supported by the New Hungary Development Plan (project no. TÁMOP-4·2·1/B-09/1/KMR-2010-0002). The authors say thanks to Hodács Composites Ltd for manufacturing the test pipes.
Notes
This paper is part of a special issue on Latest developments in research on composite materials