To reduce the product life cost of aircrafts, the conversion of major load bearing components from aluminium to carbon fibre reinforced plastics have been proposed. Large load bearing components require significantly thicker composite laminates than conventional. These ‘Ultra-Thick Laminates’ require studies into the out-of-plane behavioural and material properties before it can be used commercially.
Cohesive Zone Modelling and Arcan empirical testing are chosen to help investigate these properties and behaviour of Ultra Thick Laminates. The Cohesive Zone Modelling method in the commercial FE-software, MSC.Marc Mentat, is validated by comparing results with standardized thin coupon tests prior to further simulation. Arcan tests are to provide material properties to improve accuracy of simulations.
However, Arcan test rigs designed prior to the start of this project was not suitable for providing correct data and adjustments to the test rigs are needed. Alternatives to the Arcan test have been proposed and considerations of these tests are underway. Nevertheless, Cohesive Zone Modelling is applied to a realistic Ultra Thick Laminates component with the available material properties to provide context.
The Cohesive Zone Modelling has shown to be accurate at predicting the behaviour of delamination onset, but the load-displacement predictions were not as accurate in the Ultra Thick Laminates component as in the Cohesive Zone Modelling validations.
The sources of discrepancies in results are conceptualized and the Cohesive Zone Modelling remains a viable and potentially powerful method in delamination analysis. However, more development is required in the implementation of Cohesive Zone Modelling for larger components, such as Ultra Thick Laminates components, for Cohesive Zone Modelling to become a robust and standard analytical practice.
Source: KTH
Author: Yan, Jack
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