Three main areas investigated
Material characterization will entail investigating:
- The effect of different loading modes, environmental conditions, and fibre orientation, and developing a new high frequency test method that allows prediction of the fatigue properties of an arbitrary lay-up. This analytical capability will be experimentally validated within the project by predicting the fatigue behaviour of a large-scale component based on a limited set of coupon test data.
- Interaction of hygrothermal cycles with fatigue cycles will be developed to allow identification of worst-case test conditions and establish design guidelines. Generated data on hygrothermal effects will be linked to the developed fatigue models, allowing them to take environmental effects into account.
- Models that will be developed that can predict the behaviour of steered-fibre composites.
Different test methodology strategies:
- Development of a standard test and analysis methodology allowing prediction of low-frequency fatigue behaviour, based on high-frequency testing, enabling drastic reduction (factor 10 or more) of test duration.
- High Frequency testing: The use of non-contact measurement systems (laser vibrometer and IR camera) for fatigue high-frequency tests will allow the characterisation of fatigue damage precursors to exploit for future NDI and SHM measurements. D-STANDART will develop a standard test and analysis methodology to support the modelling of the material self-heating, the interface damage frictional heat and effect of environmental temperature and vibration loading. Furthermore, it will develop a metric for discriminate the contribution of each physical bahaviour.
Climatic Chamber and Mechanical Test ( © Delft University of Technology)
© University of Twente
- Effect of Fibre orientation: We will study the effect of fibre orientation on delamination growth by way of traditional test geometries, e.g., double cantilever beam (DCB), end loaded split (ELS) and asymmetric cut ply (ACP), but making use of non-traditional lay-ups, so that there is a change of fibre orientation across the delaminating interface. D-STANDART will develop standard test and analysis methodology to support modelling of the effect of fibre orientation on fatigue damage growth.
- Effect of environment: The two most important environmental parameters affecting the fatigue life of composites are temperature and moisture. We will study this by conducting fatigue tests on both unaged virgin specimens and specimens conditioned by hygrothermal ageing. Equilibrium moisture content measurements will be performed used to allow the accurate determination of the artificial ageing cycle duration across samples. D-STANDART will develop standard test and analysis methodology to support modelling effect of temperature and humidity on fatigue life. Fatigue tests will be performed under both temperature and moisture control. The aim is to develop knock-down factors that can be used in fatigue life predictions.