Investigation into the behaviour of hollow glass fibre bundles under compressive loading

In this study the behaviour of small epoxy resin-bonded hollow glass fibre (HGF) tows, in a range of fibre hollow fractions and external diameters, was investigated under axial compressive loading. The relative magnitudes of compression strength for HGF tows and nominally identical bundles of solid fibres of the same external diameter ( D) were measured. The interactions between fibres in a micro-tow replicated the conditions found in unidirectional composite materials. A significant degree of scatter in compression strengths were observed. However, experimental and calculated compression strengths for the range of specimens tested show a strong dependence on fibre geometry. Large fibre D and fibre hollow fraction ( K 2) appears to give higher experimental strength values relative to the equivalent solid fibre specimens. Conversely, strength values calculated using actual glass cross-sectional area indicate that smaller D, high K 2 fibres should offer the best compressive performance. It would appear from these findings that the arrangement of the fibres within the bundle (i.e. alignment, spacing, etc.) rather than the individual fibre property has an overriding effect on subsequent compression performance.