Kinematic Approach for a Global-Local Coupling: Compressive Behaviour of a Delaminated Panel:

A kinematic approach to global/local coupling has been applied to investigate the behaviour of a delaminated stiffened composite panel, by using an in-house finite element based procedure. The delamination growth phenomenon has been simulated by employing fracture elements implemented in the B2000++® code, which are based on the Modified Virtual Crack Closure Technique (MVCCT); this technique is able to compute the energy release rate on the delamination front for each fracture mode. A very fine three-dimensional mesh in the delaminated region has been considered in order to obtain a good prediction of the delamination growth. The rest of the structure has been modelled by means of shell elements. A global/local approach based on point-wise multipoint constraint has been implemented in the in-house-code and used to connect shell meshes to solid ones. A numerical application on a delaminated composite stiffened panel taken from literature has been introduced. Models characterized by different levels of complexity, i.e. without delamination, with delamination, with delamination growth have been considered and compared to understand the effectiveness of the introduced kinematic approach

Monitoring the Microseismicity through a Dense Seismic Array and a Similarity Search Detection Technique: Application to the Seismic Monitoring of Collalto Gas-Storage, North Italy

Seismic monitoring in areas where induced earthquakes could occur is a challenging topic for seismologists due to the generally very low signal to noise ratio. Therefore, the seismological community is devoting several efforts to the development of high-quality networks around the areas where fluid injection and storage and geothermal activities take place, also following the national induced seismicity monitoring guidelines. The use of advanced data mining strategies, such as template matching filters, auto-similarity search, and deep-learning approaches, has recently further fostered such monitoring, enhancing the seismic catalogs and lowering the magnitude of completeness of these areas. In this framework, we carried out an experiment where a small-aperture seismic array was installed within the dense seismic network used for monitoring the gas reservoir of Collalto, in North Italy. The continuous velocimetric data, acquired for 25 days, were analysed through the application of the optimized auto-similarity search technique FAST. The array was conceived as a cost-effective network, aimed at integrating, right above the gas storage site, the permanent high-resolution Collalto Seismic Network. The analysis allowed to detect micro-events down to magnitude Ml = −0.4 within a distance of ~15 km from the array. Our results confirmed that the system based on the array installation and the FAST data analysis might contribute to lowering the magnitude of completeness around the site of about 0.7 units

Prattica ecclesiastica civile, criminale e d'appellazione

Obra perteneciente al Fondo Antiguo de la Biblioteca de la USA

Numerical optimization of wing skin panels actuation based on s.m.a.

This article is focused on numerical investigations of smart structure concepts, developed through the integration of Smart Materials within a wing skin structure, in order to achieve prescribed surface deformation. Among the large family of Smart Materials, Shape Memory Alloys (SMAs) are considered a suitable solution for many static applications, because of their capability to transmit very large forces. This, in conjunction with other peculiarities like performance per weight ratio, justifies the increasing interest for aerospace applications. Explored architectures are aimed at controlling the chamber of a generic airfoil; performance was evaluated in terms of maximum displacement and rotation of the free panel trailing edge, estimated by a FE approach. SMA behaviour was modelled through a dedicated routine for evaluating the activation temperature and internal stress state. Several configurations were simulated, corresponding to different actuation strategies; structures capable of multi-stable actuation condition were also considered; the most efficient architectures were optimized using a genetic algorithm for further actuation improvements

An Innovative Fiber-Optic Hydrophone for Seismology: Testing Detection Capacity for Very Low-Energy Earthquakes

An innovative fiber-optic hydrophone (FOH) was developed and investigated via an experiment at sea; it is capable of operating at a very low frequency of the seismic spectrum and detecting small magnitude earthquakes. The FOH exploits an optical fiber coil wrapped around a sensitive mandrel in a Michelson interferometric configuration. The FOH operated for about seven days at a water depth of 40 m, in the Campi Flegrei volcanic area (Southern Italy), and a few meters from a well-calibrated PZT hydrophone used as a reference. Thirty-three local earthquakes occurred during the simultaneous operation of the two hydrophones, allowing a straightforward comparison of the recordings. The local earthquakes occurred at an epicentral distance less than 2.5 km from the site of recording, and were estimated to be in the range of magnitude from −0.8 to 2.7. The analysis of the recorded earthquake waveforms in the frequency and time domains allowed retrieving the response function of the FOH in the frequency range from 5 to 70 Hz. The FOH responsivity in terms of acoustic pressure reached about 230 nm/Pa and was flat in the studied frequency range. Due to the high quality of the FOH recordings, this equipment is suitable for applications addressing submarine volcanic activity and the background seismicity of active faults in the ocean

UNITED STATES PATENT: Actuator device based on shape memory alloy, and a wing flap assembly fitted with such an actuator device

A wing-flap assembly includes a flap made up of a plurality of flap sections, in which each flap section is connected to the preceding one in a rotatable manner, and one or more actuator devices adapted to control the rotation of the flap sections. Each actuator device includes an extended element made of shape memory alloy and an arch-shaped framework made of elastic material, to which the extended element is fixedly connected under tension. Each end of the extended element is fixed to a respective end of the arch-shaped framework. At least one of the actuator devices is connected at one end to the first of the flap sections, and on the other side is adapted to be connected to a wing structure

EUROPEAN PATENT: An actuator device based on a shape memory alloy, and a wing flap assembly fitted with such an actuator device

The present invention refers to an actuator device and a wing-flap assembly. As it is known, the increase in lift required for the take-off and landing phases of an aircraft is mainly obtained through the deflection of a wing-flap around a hinging axis. Such a solution implies the presence of robust control lines and complex actuation devices which significantly contribute to the weight of the whole wing structure. From an aerodynamic point of view, the local modification of the curvature of the wing profile induced by a conventional flap is limited by the excursion range of the flap itself; for this reason only the profile curvatures compatible with the finite number of deflection angles of the mobile surface can be used in operating conditions. The purpose of the present invention is that of providing a wing-flap assembly which allows the weights as well as the operating and maintenance costs to be reduced with respect to conventional wing-flap technology, as well as allowing an optimization of the aerodynamic performances of the lift devices to be obtained. According to the invention the wing-flap is able to dynamically modify its own curvature (morphing flap) according to specific design requirements. The flap is controlled through one or more actuator devices based upon shape memory alloy, which enormously reduces the total weight of the group and makes the control system simpler to manufacture