Mechanical Engineering Faculty Research


Understanding Effectiveness of Stitching in Suppression of Impact Damage: An Empirical Delamination Reduction Trend for Stitched Composites

Document Type


Publication Date

Summer 6-2012


In this paper, a novel empirical trend has been identified to understand the delamination reduction in stitched composites subjected to impact loading. This empirical-based Delamination Reduction Trend (DRT) is developed based on an extensive series of low-velocity impact tests using specimens of different laminate thicknesses, stitch densities and stitch thread linear (mass) densities, subjected over a range of impact energy levels. The DRT simply relates two parameters: normalized delamination area (DelamNorm) and stitch fiber volume fraction (Vft), to characterize the effectiveness of stitching in impact damage suppression. DRT evidently shows a bi-linear behavior: first, an initial linearly decreasing relationship of DelamNorm with Vft; and second, a plateau which indicates maximum delamination area reduction limit of 40% by stitching. Experimentally observed mechanisms are presented and discussed with the aim to justify and explain the bi-linear behavior of DRT. The DRT is further validated with numerous published literature results and has demonstrated excellent agreement.

Publication Title

Composites Part A: Applied Science and Manufacturing





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