University of Manchester

Investigation of Micro-Meso Cracking in 3D Woven Composites

Mohamed Ahmed Saleh
Project Completed

Scientific Case

The objective of this research project is to investigate the dependency of cracking mechanisms of 3D woven composites on the loading condition of the samples. It has been proven before that transverse cracking of weft yarns is the dominant cracking mechanism for 3D woven composites loaded in tension at zero direction which is along the warp yarns direction. However, the same structure of any 3D woven composite should demonstrate a different response if loaded in a multi-axial loading condition. The idea is to compare the uniaxial loaded samples cracking mechanisms and fracture response against (+/- 45) loaded samples cracking mechanisms and failure response and try to predict those failure using Image Based FEM. X-Ray CT is required, before testing, to capture the actual compacted geometry after manufacturing and infusion. This geometry will be used as an input, after segmentation, for an Image-base FEM modelling using ABAQUS Standard to simulate the various cracking mechanisms and compare the modelling results with the scanned images of the same structures. The experimental plan will require an in-situ X-Ray CT investigation along with the mechanical test. This should be the best scenario to be able to capture the cracking initiation and evolution in both cases unless the resolution does not represent a constraint. A few trial tests must be done to make sure the rig can work well while applying loading during the scan. The other alternative is to load multiple samples incrementally to various loading states (50, 60, 70, 80, 90% UTS) and scan all samples together to see the difference in the number of cracks and their sizes.
Composites

Experiment Design

- Features and Resolution
Matrix cracking, debonding and fibre breakage.

Cracks in the sample are on the scale of submicrons
Scanners and Rigs
Nikon Custom 320kV Bay
3
Not Required
2
Xradia MicroXCT
6
Tension
3

Sample & Safety

3D woven carbon fibre samples with 3 different architectures (Orthogonal, Angle Interlock and Layer to Layer)
3
Low Hazard

Scan Records

Project Report