Investigation of the Interlaminar Shear Performance of Tufted Preforms and Composites under Mode II Loading Condition.

The influences of reinforcement by tufting on the interlaminar shear performance of laminated preforms and composites are studied in the present paper. A modified T steel shearing test was established and used to achieve a pure Mode II loading (sliding). Dry tufted preform (DTP) and cured tufted composites (CTC) with varied tufting spacing are considered for the understanding of the role of infused resin and the tufting density on the mechanical properties. Meanwhile, knowledge about the role of infused resins is gained. Additionally, cured tufted composites without threads (CT'C) were prepared under the identical tufting density to evaluate the effect of tufting threads. The results show that the denser the tufting density, the stronger the interlaminar shear strength of CTC, its improvement reaches 12% compared to the non tufted composites. However, the decreased effect also exists for the tufting spacing of 9 mm. Therefore, the tufting density needs to be optimized during the tufting process to improve the interlaminar shear properties of tufted reinforcement and composites. On the contrary, tufting without thread does not affect its mechanical properties compared to the non tufted composites.