Paper number 944

IMPACT DAMAGE AND RESIDUAL STRENGTH OF MUTIAXIAL WARP KNITTED GLASS FABRIC REINFORCED POLYESTER LAMINATE

Tien-Wei Shyr, Chung Ouyang, and Yu-Hao Pan

Department of Textile Engineering, Feng-Chia University, Taichung, Taiwan, R.O.C.

Summary

This paper describes an experimental program undertaken to investigate first the low impact energy damage in multiaxial warp knitted glass fabric, which has a guasi-isotropic stitching sequence of 0°/+45°/90°/-45°, reinforced unsaturated polyester composite. Laminates made by 4-blanket, 8-blanket, and 12-blanket glass fabrics were used. The laminates were subjected to falling-weight, non-penetrating impacts at the normalized impact energies from 4 J/blanket to 16 J/blanket. A mechanistic study that impact induced delamination characterized by a butterfly shape was observed on the 4-blanket laminate. A circular shape was observed on the 8-blanket and 12-blanket laminates. The radial matrix cracks were observed on both of the delamination patterns. A conical region under the impact location does not generally break fibres and matrix cracks. Kink band shear failure was found after a compression-after-impact test. Fibre-matrix debonding between two kink band regions was observed, which transferred the compressive strength from one to another. The results show that more blanket of the laminate has high efficiency of impact energy absorption, but it has large delaminated region. The delaminated region affected the residual compressive strength, where residual compressive strength decreases as the impact delaminating region increases.

Keywords

multiaxial warp knitted fabric, impact, and compression after impact.