A physics-based computationally efficient multi-scale model for prediction of damage mechanisms in composite laminates under multi-axial fatigue loads considering the effects of thermal residual stresses and manufacturing defects

Multidirectional laminates made of unidirectional Fiber-Reinforced Plastic (FRP) composite materials have been widely used in primary fatigue load bearing structures of different industrial sectors. To reduce the time-to-market for new products and the costs associated with experimental testing, developing modeling tools with acceptable run time for prediction of fatigue behavior of FRP laminates is a crucial technological demand. Developing models for prediction of fatigue behavior in laminated composite structures is a complex task as composite laminates undergo multiple damage events in different scales. Within the full span from initiation to criticality of the damage mechanisms, the governing length scales in a FRP laminate change from the fiber size (microscale 5-20 μm) to the structural size (up till 100m wind turbine blades). This project aims at developing a novel multi-scale computationally efficient methodology for physically modelling of these damage mechanisms by deriving analytical closed form solutions at microscopic scales and implementing them at finite element structural scales. The fatigue experimental results with microscopic observation of damage mechanisms will be used for validation of the model. The models rely on variational stress analysis and a very limited set of physical parameters. Their accurate and analytical basis makes them appropriate for fast and accurate assessment of material fatigue behaviour, leading to an attractive design tool.