Session: 01-08-01: Nondestructive Evaluation and Structural Health Monitoring, 01-11-01: Wind Energy

Paper Number: 121613

121613 - A Global-Local Modeling Approach for Wave Propagation, SHM and Damage Detection in Reinforced Panels Using Integrated Piezoelectric Sensors 

Composite structures are used in critical applications including aerospace which requires the need of continuous monitoring, confirming that the state of the structure still conforms with the margins of safety employed for its proper functioning. In accordance, early damage detection presents a crucial benefit for applying immediate maintenance procedures, thus salvaging the structure and the application where such structures are deployed. The use of smart structures where piezoelectric active material is integrated into the structure possesses the advantages of facilitating structural sensing through the piezoelectric electromechanical coupling. Such active materials can be embedded inside the structure depending on the application, where piezo-ceramic material possesses greater sensing capability, but are fragile and easily breakable under high strains, whereas piezo-polymeric material provide greater ductility making them appealing to be imbedded in difficult geometries, under higher strains. That being said, introducing these elements into composite laminated structure might possess some drawbacks, such as being a spot for stress concentration and damage initiation, or increasing the complexity of manufacturing.

In order to design and study the effects of embedding such elements into the structure, it is convenient to use numerical models, such as finite element models. Many studies have modelled the piezoelectric devices using a solid model, as it is essential in commercially available FE tools, however, this induces a high computational cost, which restricts their use in complex structures. In complex structure, the tendency is to use simplified one-dimensional (beam) or two-dimensional (plate) models that are computationally convenient, but do not guarantee a good accuracy.

This paper presents forward a novel method for the damage detection in smart structures. The use of node-dependent kinematic models, based on the Carrera Unified Formulation, has led to an innovative global-local approach, with the ability to couple finite elements with different kinematics, and thus different levels of accuracy. With such approach it is possible to model a composite structure with embedded piezoelectric transducer, where the integrated patch or region is modelled using high-fidelity models, as the complex phenomena is expected to happen locally around that area. Thus, the use of layer-wise model is necessary on the level where higher accuracy is needed, as in the embedded area, whereas it remains possible to implement the cost efficient homogenized equivalent single layer models in other areas, reducing the computational cost. This approach has been used to study the lamb-wave propagation in reinforced composite panels, where a damage has been introduced. The detection of such damage through pitch and catch setup, whether the damage is a crack or a delamination, has been studied. The results show that this approach may provide accurate damage detection localization and accurate wave propagation despite the presence of localized models with sensors/ actuators.

Presenting Author: Enrico Zappino Politecnico di Torino

Presenting Author Biography: Enrico Zappino is an Associate professor at Politecnico di Torino and part of the MUL2 team since the 2010.
Under the mentorship of Prof. Carrera he obtained his Ph.D. in 2014 with a thesis on variable kinematics models for the study of composite structures. After his Ph.D. he has continued the development of advanced numerical
models applying them to different fields: smart structures, aeroelasticity, thermo-elastic problems, global-local approaches. Recently, thanks to the collaborations with UBC and UW he is developing models for virtual manufacturing of composite structures.