This study is aimed at developing a numerical tool to predict the fracture mechanics of passively and actively coupled structural systems. These definitions are related to the wide recently growing up in the technology of composite materials equipped with functional layers made of smart materials such as piezoelectric, electrostrictive, magnetostrictive and others. Their main function is providing a local conversion of energy for several goals. Very often they are used as a sensor to monitor the static and dynamic behaviour of structures. In active control of shape and of vibration energy is supplied to the transducer, which applies a suitable force or moment to the structure. Moreover, quite recently conversion is activated to store the energy by using some effect like vibration or temperature increasing, which could be dissipated otherwise. A critical issue of design of those systems is prevention of damage propagation, in case of cracking. This task can be performed in both the case of PASSIVE COUPLING in which the smart layer is only connecting the energy associated to the deformation of the structure and of ACTIVE COUPLING in which an external source of energy is connected to the smart layer and it converts this power into a suitable actuation of the mechanical system. To predict the crack propagation inside the material there are analytical and numerical approaches already assessed in the literature for classical applications where functional materials are not yet used. Among analytical approaches, there are many procedures, which require huge mathematical solutions and are effective in case of simple structures, while their application to some complicated geometries is rather different because of the lack of formulations suitable for each relevant and specific case. Numerical approaches were already widely used in fracture mechanics and in several applications, nevertheless literature show a lack of procedures applicable to the smart materials, such as the piezoceramics, which can be used for both the PASSIVELY COUPLED SYSTEMS (energy harvester and sensor) and the ACTIVE DEVICES (actuators). A main goal of this study is developing a numerical tool able to predict the mechanical behaviour of smart structures equipped with piezoelectric layers in case of crack damage. It could be used in the design activity for a consistent prediction of the smart system reliability. A comprehensive approach is described. As it is used in fracture mechanics the smart material behaviour is described by calculating the so-called Stress Intensity Factor (SIF), the J-integral and the crack propagation in fracture of the electromechanical coupling, in passive and active configuration.

NUMERICAL TOOLS FOR FRACTURE MECHANICS PREDICTION OF PASSIVELY AND ACTIVELY COUPLED STRUCTURAL SYSTEMS / MOHAMMADZADEH SARI, Mehdi. - (2014). [10.6092/polito/porto/2534708]

NUMERICAL TOOLS FOR FRACTURE MECHANICS PREDICTION OF PASSIVELY AND ACTIVELY COUPLED STRUCTURAL SYSTEMS

MOHAMMADZADEH SARI, MEHDI
2014

Abstract

This study is aimed at developing a numerical tool to predict the fracture mechanics of passively and actively coupled structural systems. These definitions are related to the wide recently growing up in the technology of composite materials equipped with functional layers made of smart materials such as piezoelectric, electrostrictive, magnetostrictive and others. Their main function is providing a local conversion of energy for several goals. Very often they are used as a sensor to monitor the static and dynamic behaviour of structures. In active control of shape and of vibration energy is supplied to the transducer, which applies a suitable force or moment to the structure. Moreover, quite recently conversion is activated to store the energy by using some effect like vibration or temperature increasing, which could be dissipated otherwise. A critical issue of design of those systems is prevention of damage propagation, in case of cracking. This task can be performed in both the case of PASSIVE COUPLING in which the smart layer is only connecting the energy associated to the deformation of the structure and of ACTIVE COUPLING in which an external source of energy is connected to the smart layer and it converts this power into a suitable actuation of the mechanical system. To predict the crack propagation inside the material there are analytical and numerical approaches already assessed in the literature for classical applications where functional materials are not yet used. Among analytical approaches, there are many procedures, which require huge mathematical solutions and are effective in case of simple structures, while their application to some complicated geometries is rather different because of the lack of formulations suitable for each relevant and specific case. Numerical approaches were already widely used in fracture mechanics and in several applications, nevertheless literature show a lack of procedures applicable to the smart materials, such as the piezoceramics, which can be used for both the PASSIVELY COUPLED SYSTEMS (energy harvester and sensor) and the ACTIVE DEVICES (actuators). A main goal of this study is developing a numerical tool able to predict the mechanical behaviour of smart structures equipped with piezoelectric layers in case of crack damage. It could be used in the design activity for a consistent prediction of the smart system reliability. A comprehensive approach is described. As it is used in fracture mechanics the smart material behaviour is described by calculating the so-called Stress Intensity Factor (SIF), the J-integral and the crack propagation in fracture of the electromechanical coupling, in passive and active configuration.
2014
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11583/2534708
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