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AIAS 2017
46° CONVEGNO NAZIONALE

6-9 SETTEMBRE 2017


Programma dei lavori
Programma generale

GIOVEDÌ 7 SETTEMBRE
08:00-08:30
Registrazione
08:30-09:30
Memoria invitata Prof. Fatemi
09:30-11:10
Sessioni parallele I
11:10-11:30
Coffee break
11:30-13:10
Sessioni parallele II
13:10-14:30
Pranzo
14:30-16:30
Sessioni parallele III
16:30-16:50
Coffee break
16:50-18:30Assemblea dei Soci
20:30-00:00Cena sociale
VENERDÌ 8 SETTEMBRE
08:30-09:30
Memoria invitata Prof. Frasconi
09:30-11:10
Sessioni parallele IV
11:10-11:30
Coffee break
11:30-13:10
Sessioni parallele V
13:10-14:30
Pranzo
14:30-15:30
Sessioni parallele VI
15:30-16:10
Coffee break
16:10-17:50
Sessioni parallele VII
17:50-18:00Chiusura congresso
MERCOLEDÌ 6 SETTEMBRE
13:00 – 14:00
Registrazione
14:00 – 14:30
Saluti di benvenuto
14:30 – 16:10
Sessione Juniores I
16:10 – 16:30
Coffee break
16:30 – 17:50
Sessione Juniores II
18:20
Partenza per Calci
19:00 – 20:00
Visita alla Certosa di Calci
20:00 – 22:30
Cena di benvenuto
22:30 – 23:00
Rientro a Pisa
Multiaxial Fatigue and Applications to Additive Manufactured Metals

Ali Fatemi,
Ring Industry Endowed Chair Professor and Department Chair, Mechanical Engineering Department, University of Memphis, Memphis, Tennessee
Distinguished University Professor and Director Fatigue and Fracture Research Laboratory
Fellow of ASME

Abstract
This presentation is divided into two parts. In the first part, a brief overview of some important issues in multiaxial fatigue and life estimation will be presented. These include damage mechanisms and quantification parameters, material constitutive response and non-proportional hardening, cycle counting and damage accumulation in variable amplitude loading, and mixed-mode crack growth. It will be shown that capturing the correct damage mechanism is essential to develop a proper damage quantification parameter for robust multiaxial fatigue life estimation. Additional cyclic hardening of some materials under non-proportional multiaxial loading and its dependence on the load path as well as material microstructure will also be discussed. It is argued that critical plane damage models with both stress and strain terms are most appropriate since they can reflect the material constitutive response under non-proportional loading. Importance of a proper cycle counting method to identify cycles in a variable amplitude load history, and capability of the linear cumulative damage rule to sum damage from the counted cycles will also be discussed. As mixed-mode crack growth can constitute a significant portion of the total fatigue life, analysis of crack growth rates and correlations under combined stresses will be presented. Several models as well as some simple approximations in capturing the aforementioned effects in multiaxial fatigue life estimations will also be described. In the second part of the presentation, applications of the aforementioned issues to multiaxial fatigue analysis of additive manufactured metals, specifically Ti-6Al-4V alloy, will be presented. This alloy is one of the most common alloys made by additive manufacturing and has a wide range of applications, particularly in the aerospace and biomedical industries. Recent experimental data generated using tubular specimens of this alloy made by selective laser melting as a common method of additive manufacturing process by powder bed fusion will be presented. The behavior and performance will then be compared with those obtained from its conventional manufactured counterpart, namely wrought Ti-6Al-4V alloy.

Biography
Dr. Fatemi received his B.S. and M.S. degrees in structural analysis and design and his Ph.D. in Mechanical Engineering in 1985, all from The University of Iowa. He was on the faculty of Mechanical Engineering at Purdue University-Fort Wayne from 1985 to 1987, and has been on the faculty of Mechanical, Industrial and Manufacturing Engineering at the University of Toledo since 1987. He was promoted to Associate Professor in 1991, and to Professor in 1996. He is currently a Distinguished University Professor.  He  has taught many subjects in mechanics and design. At the graduate level, he has been teaching courses on fatigue of materials and structures, fracture mechanics, advanced mechanics of materials and mechanics of composite materials, and experimental mechanics. He has directed theses and dissertations of more than 50 students at the master and doctoral levels, as well as working with post-doctoral fellows.
Dr. Fatemi's primary research interests and publications involve materials mechanical behavior in general, and in fatigue and fracture mechanics in particular. He has published over 200 refereed papers dealing with fatigue and fracture, both at the basic level helping to understand fundamental fatigue damage mechanisms as well as in the applied areas facilitating applications of the knowledge learned to the design and life prediction of engineering components and structures. He has co-authored the second edition of a fatigue textbook entitled "Metal Fatigue in Engineering" published by Wiley in 2000. A list of Dr. Fatemi's publications can be found at "Google Scholar.com/citations". Dr. Fatemi has had sponsored research projects from many companies, foundations, and government agencies. Most of these research projects are/were carried out in the Fatigue and Fracture Laboratory at UT. This experimental research laboratory houses state of the art equipment including several servo-hydraulic testing systems.
Dr. Fatemi is a Fellow of the American Society of Mechanical Engineers (ASME), a member of the American Society for Testing and Materials (ASTM) Committee E-8 on Fatigue and Fracture, and the American Academy of Mechanics. He is on the editorial boards of the International Journal of Fatigue, Theoretical and Applied Fracture Mechanics and the Journal of Advances in Mechanical Engineering. He has received several awards for his research, including the University of Toledo Outstanding Research Award in 2002, and the Sigma Xi/Dion Raftopoulos Award for Outstanding Research in 2008. He has been a member of the Scientific Committee of and a Keynote Speaker at international conferences on fatigue and fracture.



A MECHANICAL SYSTEM TO ISOLATE FROM SEISMIC NOISE THE OPTICAL COMPONENTS OF THE ADVANCED VIRGO INTERFEROMETER

Franco Frasconi
INFN - Pisa

Abstract
The recent announcement of the first observation of a Gravitational Wave signal emitted by a merger of a Binary Black Hole (BBH) system, marked a fundamental achievement in the scientific research. This important discovery, announced by the VIRGO and LIGO Collaborations, has been possible thanks to the second generation laser interferometer detectors, based on complex mechanical systems developed to isolate the optical components from seismic noise. Since the very beginning the INFN Pisa Group conceived the so called Superattenuator, a sophisticated mechanical structure based on the working principle of a multistage pendulum and adopted to isolate the optical components from seismic noise. With this solution the detection bandwidth of the laser interferometer has been extended in the low frequency region where many astrophysical sources are expected to emit mainly low frequency gravitational waves. The description of the main elements of the Superattenuator together with the technological solution developed to fulfil the requirements of the second generation interferometer, Advanced VIRGO, will be presented.


Biography
Dr. Frasconi, received his degree on Physics at the Bologna University developing a thesis work on the first evidence of the “beauty” quark in the baryons production from proton-proton interactions at high energy. For many years he acquired an important expertise in this field at the CERN Laboratory (Switzerland) where he worked at different experiments on particles physics. In particular, he was involved in the L3 experiment at LEP and in the LAA Project based on the development of new technologies for particles detectors to be installed on future colliders. Dr. Frasconi was responsible of the development, construction and operation of the first vertex chamber installed within the ZEUS detector at DESY Laboratory (Germany). The ZEUS Detector was a multi-purpose experiment installed on the HERA collider conceived to study the fundamental physic of the electron-proton interactions at high energy. In 1995 dr. Frasconi has been appointed, at the Syracuse University (USA), as Research Associate Professor in the grant of the CLEO III Experiment at Cornell University. His expertise was fundamental in the development, construction and installation of a Cerenkov detector for particles identification in the study of the electrons-positrons interactions. Since 1997 dr. Frasconi works at the National Institute for Nuclear Physics of Pisa (INFN Pisa) in the Gravitational Physics field and in particular he is deeply involved in the Gravitational Waves research and studies. His interests are connected to the development of the modern ground based laser interferometric detectors for Gravitational Waves continuous observations.  His professional activity is mainly centred on the study of seismic noise and on the filtering systems to inhibit its transmission to the optical components. In this contest he acquired a fundamental experience in the development of a mechanical system, called Superattenuator, to isolate from seismic noise the VIRGO and Advanced VIRGO mirrors. The adoption of this hybrid system (passive and active) marked a crucial step forward in the conceptual design of the interferometric detectors for Gravitation Waves research, extending their detection bandwidth in the low frequency region (below 100 Hz). Among other scientific interests, dr. Frasconi is also involved on the study of Thermal Noise problems of complex systems for Gravitational Waves detectors, with a specific attention to the possibility to develop last stage monolithic payloads to be operated at cryogenic temperatures in the next generation detectors.
In 2016, together with the colleagues of the VIRGO and LIGO Collaborations, dr. Frasconi has been awarded with the “Breakthrough Prize in Fundamental Physics” for the results obtained on Gravitational Waves research.


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