Three-dimensional assessment of low velocity impact damage in particle toughened composite laminates using micro-focus X-ray computed tomography and synchrotron radiation laminography

Abstract

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.

The influence of toughening-particles in CFRPs on low velocity impact damage resistance performance

“…The echelon crack segments indicate that failure occurred predominantly in shear in agreement with previous studies [38,39]. Such behaviour supports the phenomenon that delamination propagation caused by low velocity impact occurs predominantly in mode II [37,[40][41][42][43].…”

In situ synchrotron tomographic evaluation of the effect of toughening strategies on fatigue micromechanisms in carbon fibre reinforced polymers

“…To date, several approaches to toughening have been developed to a sufficient level of maturity that they are employed in service in CFRPs for aerospace applications; however, the underpinning micromechanisms of failure associated with the modified microstructures have not been widely investigated. Studies on toughening micromechanisms in composite laminates are relatively limited [10,[21][22][23][24], and the consequence of fatigue loading on the effectiveness of toughening strategies in particular has been largely neglected.…”

Interlaminar fracture micro-mechanisms in toughened carbon fibre reinforced plastics investigated via synchrotron radiation computed tomography and laminography

“…Damage inside a composite material can be made visible via x--ray computed tomography (CT) using laboratory [20,21] and synchrotron sources [22--25] with specimen geometries adapted to the CT scanning technique. This permits in situ observations of toughening mechanisms to be made using non--invasive techniques away from free--edges under representative stress states.…”