Abstract
The influence of specimen twisting during anti-plane shear (mode III) loading in composite split beam specimens is studied using the split-shear torsion test. Tests were conducted on specimens with different thicknesses and delamination lengths to produce different amounts of specimen twisting prior to fracture. It is shown that specimen twisting causes mode I stresses to develop that are proportional to the angle of twist, thereby producing mixed-mode I-III conditions along the delamination front. This causes near-tip transverse cracks to initiate, prior to delamination advance, at an orientation related to the mode mix, and therefore to the angle of twist. Unlike what occurs in homogeneous materials, it is observed that the laminate's fibers restrict the amount by which these transverse cracks can rotate during extension, and that transverse crack extension is accompanied by planar delamination advance. The overall fracture surface evolution is therefore strongly controlled by specimen and test geometry. The influence of these findings on the apparent delamination toughness as obtained from composite split beam tests, as well as on mode III delamination toughness testing in general, is discussed.
| Original language | English (US) |
|---|---|
| State | Published - 2015 |
| Event | 20th International Conference on Composite Materials, ICCM 2015 - Copenhagen, Denmark Duration: Jul 19 2015 → Jul 24 2015 |
Other
| Other | 20th International Conference on Composite Materials, ICCM 2015 |
|---|---|
| Country/Territory | Denmark |
| City | Copenhagen |
| Period | 7/19/15 → 7/24/15 |
Keywords
- Delamination
- Fracture
- Matrix cracking
- Mixed-mode
- Mode III
ASJC Scopus subject areas
- General Engineering
- Ceramics and Composites