Damage tolerance design for thin ply textile composites (DAMTEX)

Purpose and goal

The aircraft industry is interested in thin ply composites, which can provide improved strength, but increased use of such materials requires reliable methods to predict damage growth. The aim of the project was to develop such methods for composites with plies woven from thin bands of carbon fibres. A simplified modelling technique has been developed to efficiently model a laminate with a large number of thin plies. The method has been used to predict impact damage and its influence on strength, and has shown good agreement with experiments.

Results and expected effects

The Swedish company Oxeon has developed a unique type of thin carbon fibre weaves for high performance composites. The materials allow lower weight and faster production, and thereby reductions in cost and fuel consumption. The project has shown the possibilities to use the materials in aircraft structures and has laid a foundation for design according to the requirements by the aircraft industry. The project has shown that reliable models must include both fibre fracture within the plies, and a certain fraction of the fracture surfaces between plies.

Approach and implementation

The project has been a two year collaboration between Swerea SICOMP and Oxeon in Sweden and the aircraft subcontractor Aernnova and University of Girona in Spain. Models for damage growth in thin band weave composites have been developed by adapting approaches for conventional composites composed of unidirectional plies. The models have been applied and validated by comparison with tests of impact and strength after impact, performed within the project. The results for two different weave thicknesses have been compared with material of normal ply thickness.