Abstract
In this study, digital volume correlation (DVC) is applied to high-resolution synchrotron tomograms of glass fibre-reinforced epoxy composites, in both single- and multi-fibre configurations, subjected to longitudinal tension. The investigated single-fibre composites experience fibre fracture, longitudinal debonding, and matrix cracking, with their combined effects on strain recovery captured. In contrast, multi-fibre composites, consisting of the same constituents, undergo more confined damage around a fibre break due to the presence of neighbouring fibres, resulting in strain recovery over much shorter axial and radial distances from fibre breaks. The extent of damage in both specimen configurations is quantified volumetrically, and the concept of ineffective volume is introduced to compare single-fibre and multi-fibre damage responses. The study highlights a critical discrepancy between single- and multi-fibre systems during axial loading. Implications for extracting constituent properties from single-fibre test methods are discussed.