Tomographic imaging using both laboratory sources and synchrotron radiation (SR) was performed to achieve a multi-scale damage assessment of carbon fibre composites subjected to impact damage, allowing various internal damage modes to be studied in three-dimensions. The focus of this study is the comparison of different tomographic methods, identifying their capabilities and limitations, and their use in a complementary manner for creating an overall 3D damage assessment at both macroscopic and microscopic levels. Overall, microfocus laboratory computed tomography (µCT) offers efficient routine assessment of damage at mesoscopic and macroscopic levels in engineering-scale test coupons and relatively high spatial resolutions on trimmed-down samples; whilst synchrotron radiation computed tomography (SRCT) and computed laminography (SRCL) offer scans with the highest 1 image quality, particularly given the short acquisition times, allowing damage micromechanisms to be studied in detail.

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Results are presented studying the contribution of particle toughening to impact damage resistance in carbon fibre reinforced polymer materials. Micro-focus Xray computed tomography and synchrotron radiation computed laminography were used to provide a novel, multiscale approach for assessing impact damage. Thin (1mm thick) composite plates containing either untoughened or particle-toughened resin systems were subjected to low velocity impact.Damage was assessed three-dimensionally at voxel resolutions of0.7 µm and 4.3 µm using SRCL and µCT respectively; the former being an innovative approach to the laterally extended geometry of CFRP plates. Observations and measurements taken from µCT scans captured the full extent of impact damage on both material systems revealing an interconnected network of intra-and inter-laminar cracks. These lower resolution images reveal that the particletoughened system suppresses delaminations with little effect on intralaminar 1 damage. The higher resolution images reveal that the particles contribute to toughening by crack deflection and bridging.

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In this paper, the effect of introducing different phases of fibre reinforcement in epoxy matrix at the dressed site in adhesively bonded external patch repair for damaged glass/epoxy composites under in-plane compressive loads was investigated. Three repair materials consisting of an epoxy matrix reinforced with either micro sized particulate fibres, chopped short fibres or continuous fibres were used in this study. Since this investigation extensively focuses on the effect of different types of fibre reinforcements on residual compression properties of repaired glass/epoxy composite laminates, the external patches were avoided. Acoustic Emission (AE) and Digital Image Correlation (DIC) were utilized to form qualitative and quantitative assessments of the damage progression profile. The compression results illustrate that reinforcing the epoxy adhesive material with glass fibres significantly increased the residual compression strength of repaired glass/epoxy composite specimens. In particular, the use of chopped fibre reinforced adhesive repair material improved the average residual compressive strength by 18.91 % in comparison to the specimens conventionally repaired using neat epoxy resin.