ONGOING ACTIVITIES

Damage tolerance analyses of composite structures: the activity is based on the application of an efficient modeling technique developed in the past years to model multiple delaminations in structural components; the technique has been successfully applied to model ultimate load carrying capability, failure mode and post-failure response of composite T-Joints, compression after impact coupons, tapered beams, curved laminates and structural details of rotorcraft blades; ongoing activities are aimed at applying the approach for the optimal design of a composite T-Joint and at integrating within the modeling approach a constitutive law for matrix cracking; the results obtained are promising for the development of an approach capable of representing intralaminar, interlaminar damage and their interaction without requiring models developed at the microstructural levels.
Ceramic Matrix Composites: a multi-scale approach has been developed for short-fiber reinforced ceramic materials based on a meso-scale representation of material structure; the numerical model has been applied to identify the properties of the constitutive phases in linear and non-linear ranges and to predict by means of virtual testing a damage threshold and a failure envelope in combined stress states; ongoing activities are related to the application of the approach to new types of materials and extension to thermal-mechanical analyses;
Improvement and validation of cohesive approaches: cohesive zone models have been improved to model fiber bridging phenomena and embedded fiber optic sensors have been used to validate the prediction of strain fields in the vicinity of interlaminar cracks; ongoing activities are aimed at the application of cohesive zone models to the design of health monitoring systems, to the development of constitutive law for adhesive interfaces and to the introductions of the effects of frictions and strain rate during dynamic propagation to correctly predict damage extension during unstable dynamic propagation.

FUTURE PLANS

Regarding the structural integrity of components in fiber reinforced plastics, the activity planned for the next years will be organized according to the following goals:

• improvement of the constitutive laws for modeling matrix cracking in polymeric matrix composites and development of an approach for the prediction of interactions between inter- and intra-laminar damages;
• application of the numerical tools developed in various scenarios such as the evaluation of critical damage sizes for the design of health monitoring systems and predictions of strength envelopes of structural components in damaged conditions;
• improvement and application of the constitutive laws developed to the study the dynamic propagation of fractures and dynamic phenomena at the structural level such as the impact response of composite structures.

The activities related to ceramic matrix composite will be continued in order to extend the approaches to other types of materials and to thermo-mechanical analyses. The multi-scale approach based on virtual testing on meso-scale models will be applied to develop non-linear homogenized material models to be used at the scale of structural components and the general approach will be assessed with experimental activities.
Moreover, it will be explored the possibility to activate co-operations regarding the application of the numerical tools developed by the lab to long-fiber reinforced ceramic or carbon matrix composites, to recycled composite materials and to study the integrity of structural components manufactured by using self-healing materials.

ERC KEYWORDS

• PE8-9 Materials engineering (biomaterials, metals, ceramics, polymers, composites, etc.)
• PE5-1 Structural properties of materials
• PE8-4 Computational Engineering
• PE8-1 Aerospace Engineering

FREE KEYWORDS

• Composite materials
• Structural integrity