Shape of a delamination in stitched laminate after a drop weight impact test
Mateusz Kozioł*, Arkadiusz Kulawik**, Józef Śleziona* *Politechnika Śląska, Katedra Technologii Stopów Metali i Kompozytów, ul. Krasińskiego 8, 40-019 Katowice, Poland **Główny Instytut Górnictwa, Zakład Inżynierii Materiałowej, pl. Gwarków 1, 40-166 Katowice, Poland
Quarterly No. 1, 2007 pages 25-31
DOI:
keywords: stitched laminate, delamination, drop weight test
abstract The paper presents the results of an after-impact observation of stitched laminates with various combination of stitch length and stitch spacing. The aim of the investigations was to show an influence of these stitching parameters on delamination shape in stitched laminate. 10-layer polyester resin - glass fabric laminates: unstitched and stitched with various stitch length (4¸11 mm) and various stitch spacing (5¸20 mm), were put to the impact tests. The influence of the stitching para¬meters on after-impact specimens’s condition was determined. Also the influence of the parameters on after-impact delamination surface and delamination range was determined. Basing on obtained results it was found that stitching of the reinforcing layers improves the delamination thoughness of the laminates. The improvement is dependent on stitch length and stitch spacing. The differences in delamination surface of tested laminates are relatively low, what certifies a possibility of significant improvement in delamination thoughness by relatively low stitch density. Comparison of quantitative factors, like delamination surface and delamination range indicates, that the stitch spacing has stronger influence on delamination surface, comparing with stitch length. Whereas, the stitch length has a bit stronger influence on delamination range, comparing with stitch spacing. Considering the delamination thoughness, a factor of a major weight is the delamination surface - so, advantageous is “steering” the stitch density in stitched laminate resulting in minimizing the stitch spacing.