Abstract
Delamination growth is a key damage mode threatening the structural integrity of fibre reinforced polymer composite structures. To guide design and damage management of composite structures, research efforts have been made to understand delamination behaviours and establish standardized evaluation methods based mainly on one-dimensional delamination tests. However, as most delamination growth in real structures will be planar, the question arises whether these approaches are adequate to evaluate planar delamination behaviour.
In this study, a novel experimental method was developed to investigate the planar delamination behaviour under quasi-static out-of-plane loading. The planar central loaded split (PCLS) specimen was designed to investigate the planar delamination behaviour under mode II loading condition. By analysing digital image correlation (DIC) and C-scan data, the delamination progress was monitored. An acoustic emission (AE) system was used to capture the initiation of damage and to identify different damage types.
The planar delamination growth was found to be dependent on the stacking sequence and interface properties. Additionally, it was found that positioning a rubber mat between the indenter and the specimen prevented the occurrence of delaminations at undesired interfaces. The artificially embedded delamination propagated in the direction to which the fibre orientation of the layer above the crack interface was parallel, but migrated initially to an upper interface at the place where the fibre was perpendicular. A constant increase in the load was observed even though the delamination propagated. The significant drop of loading seen at the end of the test was attributed to the substantial surface cracking.
The research results provide a clearer understanding of the mechanisms of planar delamination under out-of-plane loading. Furthermore, combining with the experimental results, numerical simulation will be conducted to characterize planar delamination behaviour qualitatively and quantitatively, thus to establish a more reliable assessment method for planar delamination growth
In this study, a novel experimental method was developed to investigate the planar delamination behaviour under quasi-static out-of-plane loading. The planar central loaded split (PCLS) specimen was designed to investigate the planar delamination behaviour under mode II loading condition. By analysing digital image correlation (DIC) and C-scan data, the delamination progress was monitored. An acoustic emission (AE) system was used to capture the initiation of damage and to identify different damage types.
The planar delamination growth was found to be dependent on the stacking sequence and interface properties. Additionally, it was found that positioning a rubber mat between the indenter and the specimen prevented the occurrence of delaminations at undesired interfaces. The artificially embedded delamination propagated in the direction to which the fibre orientation of the layer above the crack interface was parallel, but migrated initially to an upper interface at the place where the fibre was perpendicular. A constant increase in the load was observed even though the delamination propagated. The significant drop of loading seen at the end of the test was attributed to the substantial surface cracking.
The research results provide a clearer understanding of the mechanisms of planar delamination under out-of-plane loading. Furthermore, combining with the experimental results, numerical simulation will be conducted to characterize planar delamination behaviour qualitatively and quantitatively, thus to establish a more reliable assessment method for planar delamination growth
| Original language | English |
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| Title of host publication | Proceedings of the 31st symposium of ICAF - the International Committee on Aeronautical Fatigue and Structural Integrity |
| Place of Publication | Delft |
| Number of pages | 14 |
| Publication status | Published - 2023 |
| Event | ICAF 2023 – the 38th Conference and 31st Symposium of the International Committee on Aeronautical Fatigue and Structural Integrity: Structural Integrity In A World In Transition - Theater de Veste, Asvest 1, 2611 PK, Delft, Netherlands Duration: 26 Jun 2023 → 29 Jun 2023 https://www.icaf2023.nl/ |
Conference
| Conference | ICAF 2023 – the 38th Conference and 31st Symposium of the International Committee on Aeronautical Fatigue and Structural Integrity |
|---|---|
| Abbreviated title | ICAF 2023 |
| Country/Territory | Netherlands |
| City | Delft |
| Period | 26/06/23 → 29/06/23 |
| Internet address |
Keywords
- Planar delamination
- Stiffness degradation
- Delamination migration
- Mode II fracture