Angelo Tatì

Analysis of 3D Motion Data from Shaking Table Tests on a Scaled Model of Hagia Irene, Istanbul

The present paper focuses on the use of a 3D motion capture system for the dynamic identification and the damage monitoring of a 1:10 scaled mock-up (representing the large historic masonry structure of Hagia Irene, Istanbul) tested on shaking table at the ENEA Casaccia Research Center located near Rome, Italy. The dynamic identification of the structure during the shaking table tests was obtained by several techniques of Experimental Modal Analysis (EMA), such as FRF, FDD and EFDD. To such purpose Displacement Data Processing (DDP) of a large number of markers of the 3DVision (the passive 3D motion capture system installed at the ENEA laboratory) was performed. Markers were located on the tested mock-up accordingly to the indications of preliminary FEM analysis and modal shapes. Also conventional accelerometers were placed on the physical model and used as reference for the analysis of 3DVision data. In addition, the analysis of Markers Relative Displacements (MRDs) was useful to detect the occurrence and development of fractures during the tests, contributing to assessing the actual progress of the structural damage. The results from EMA techniques and MRDs analysis of 3DVision data are illustrated, showing the potentialities of this monitoring system in integrating the two complementary approaches.

Analysis of CFRP Joints by Means of T-Pull Mechanical Test and Ultrasonic Defects Detection

Defects detection within a composite component, with the aim of understanding and predicting its mechanical behavior, is of great importance in the aeronautical field because the irregularities of the composite material could compromise functionality. The aim of this paper is to detect defects by means of non-destructive testing (NDT) on T-pull samples made by carbon fiber reinforced polymers (CFRP) and to evaluate their effect on the mechanical response of the material. Samples, obtained from an industrial stringer having an inclined web and realized with a polymeric filler between cap and web, were subjected to ultrasonic monitoring and then to T-pull mechanical tests. All samples were tested with the same load mode and the same test configuration. An experimental set-up consisting of a semiautomatic C-scan ultrasonic mapping system with a phased array probe was designed and developed, optimizing control parameters and implementing image processing software. The present work is carried out on real composites parts that are characterized by having their intrinsic defectiveness, as opposed to the previous similar results in the literature mainly obtained on composite parts with artificially produced defects. In fact, although samples under study were realized free from defects, ultrasonic mapping found defectiveness inside the material. Moreover, the ultrasonic inspection could be useful in detecting both the location and size of defects. Experimental data were critically analyzed and qualitatively correlated with results of T-pull mechanical tests in order to better understand and explain mechanical behavior in terms of fracture mode.

Rockfalls Monitoring Along Eastern Coastal Cliffs of the Favignana Island (Egadi, Sicily): Preliminary Remarks

Favignana island (Sicily, Italy) is a historical and environmental attraction site frequented by tourists during the long warm season of the year. For several centuries the calcareous sandstone outcropping in the east side of the island has been extracted and used as building stone. Actually the quarries and the caves are undergoing to erosional and gravitational processes that are influencing the touristic use. As well as putting at risk the safety of people attending the area, the diffused rock falls are likely to jeopardize sites of great anthropological value that, once destroyed, can no longer be reconstructed. An integrated monitoring project of the cliffs is aimed to identify the most active areas and to provide support to the local government’s policies in the implementation of mitigation measures. If adequate measures will be taken in the future, operators and users of the tourist circuit will have the opportunity to enjoy these amazing areas with lower level of landslide risk.

Motion Magnification for Urban Buildings.

Vibration monitoring of buildings in the urban environment is a relevant issue for health survey and early damaging detection in sustainable and enhanced resilient cities. To this end, we explore the potentialities of vibration monitoring by motion magnification analysis that acts like a microscope for motion in video sequences, but affecting only some groups of pixels. The magnified motion is a new discipline in the field of the analysis of mechanical structures and buildings. It was developed from the analysis of small motions in videos. The motion magnification uses the spatial resolution of the video camera to extract physical properties from images to make inferences about the dynamical behavior of the observed object. The methodology does not rely on optics, but on algorithms capable to amplify only the tiny changes in the video frames, while the large ones remain. Recently, a number of experiments conducted on simple geometries like rods and other small objects, as well as on bridges, showed the reliability of this methodology compared to accelerometers and laser vibrometers. The extension of magnified motion to monitoring of buildings would provide many advantages: a clear, simple, immediate and intuitive diagnosis of the structure, flexibility, predictive potentialities, ease of use, low costs. But also some difficulties still do exist and are discussed. Here we give an introduction to the methodology and some case-studies, both in laboratory and in the real-world (see videos from the link): applications to the short-term urban resilience is straightforward.

LWIR and MWIR thermography tools for composites assessment

Smart methods for assessing the integrity of a composite structure are essential to both reduce manufacturing costs and out of service time of the structure due to maintenance. Nowadays, thermal non-destructive testing (NDT) is commonly used for assessing composites. This research work evaluates the potential of various infrared thermography (IRT) approaches for assessing different types of fabricated defects (i.e. impact damage, inclusions for delaminations, etc) on Glass Fibre Reinforced Polymer (GFRP) and Carbon Fibre Reinforced Polymer (CFRP) plates. Measurements were performed using LWIR and three active approaches: a) pulsed thermography using the flash method (xenon flash lamps), b) transient themography using IR-heating pulse, and c) thermographic inspection for cooled sample by freezing in -20 °C and then use monitoring. Furthermore, integrated flash thermography by employing a MWIR system was also used.