Rosa De FinisUniversità del Salento | Unisalento
Rosa De Finis
PhD
About
60
Publications
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568
Citations
Citations since 2017
Introduction
Additional affiliations
October 2015 - present
Instituto Tecnologico de Aeronautica-ITA
Position
- Researcher
October 2015 - March 2016
November 2014 - November 2017
Publications
Publications (60)
The current study discusses two aspects of an infrared thermography-based local SHM system for monitoring damage evolution during fatigue of composites materials, namely, pre-macrocrack damage (Stage I) followed by subsequent crack growth (Stage II).The crack density is a very well-known damage parameter representing the actual mechanical state of...
The fatigue crack propagation behaviour of material fabricated by the SLM process is investigated by using several complementary experimental techniques aiming at addressing the problems of early identification of crack initiation and growth, the transition between the fatigue crack growth regimes, and the assessment of parameters capable of descri...
The fatigue behaviour and intrinsic dissipations are studied in the present research by using different approaches: a thermography-based one leading to the use of a second harmonic amplitude temperature component as a damage parameter and the one using the mechanical energy input related to the energy dissipated during fatigue processes. Moreover,...
The use of thermal indexes assessed by monitoring rapid fatigue tests with infrared detectors as reliable damage parameters to reconstruct S/N curve is a topic still presenting open points. First of all, the selection of the proper thermal index representing damage is a topic to be explored and also the relationship between the damage from rapid st...
The degradation of materials in the satellites of the low earth orbit (LEO) is attributable to the hostile environment to which they are subjected. The main degradation mechanisms are related to the intense Ultraviolet (UV) radiation (100 ÷ 200 nm), the high-temperature range (-175 ÷ 160 ° C), the collisional impact with dust, micro meteors, ionizi...
This paper investigates the possibility to evaluate the crack tip position, crack growth rate and stress intensity factor (SIF), in order to derive the Paris law by starting from the temperature distribution measured by means of an infrared camera, with high geometrical resolution. In more detail, constant amplitude, fully reversed, stress controll...
The structural health monitoring of composite structures represents an important tool for engineers to investigate and predict the mechanical behaviour of components in presence of defects or more in general damages. In this regard, non-destructive techniques are used for localising and characterising defects during operating conditions or maintena...
Thermoelastic Stress Analysis (TSA) is an experimental technique used for describing the stress state and the mechanical behaviour of materials subjected to linear-elastic deformations. The classic TSA theory consists of a simple relation between temperature and stress variations and was successfully applied in fracture mechanics for SIF and crack...
The crack density is a very well-known damage parameter representing the actual mechanical state of the material in terms of stiffness degradation. In effect, for laminates presenting off-axis laminae, crack density is useful for determining the “characteristic damage state” (CDS) that is related the load carrying capability of the laminate.
In lit...
Background
The Stress Intensity Factor (SIF) is used to describe the stress state and the mechanical behaviour of a material in the presence of cracks. SIF can be experimentally assessed using contactless techniques such as Thermoelastic Stress Analysis (TSA). The classic TSA theory concerns the relationship between temperature and stress variation...
Friction Stir Welding (FSW) is a solid-state welding process and currently turns out to be the most widely used friction joining technique for light alloys, dissimilar materials, and metals that are not easily weldable. This process offers many advantages with respect to the traditional welding methods and it is considered an energy-saving, environ...
Adhesive bonding is a material joining process in which an adhesive, placed between the surfaces, solidifies to produce a strong bond. In this regard, adhesively bonded joints represent an interesting alternative to mechanical joints and provide many advantages over conventional mechanical fasteners: continuity of the structure, high strength-to-we...
This work deals with the analysis in the frequency domain of the temperature signal and mechanical energy rate of C45 steel under two different fatigue stepwise loading series at stress ratios of 0.1 and −1. It was first investigated the energy distribution among the harmonic components of the signals to understand possible variations caused by a d...
This work deals with the analysis in the frequency domain of the temperature signal and mechanical energy rate of C45 steel under two different fatigue stepwise loading series at stress ratios of 0.1 and -1. It was first investigated the energy distribution among the harmonic components of the signals to understand possible variations caused by a d...
Methods and techniques presented in literature for studying the fatigue behaviour of materials involve expensive, long lasting experimental campaigns and often a data analysis providing any information about damage localisation and occurrence. To avoid a time-consuming mechanical characterisation and to provide more information about where and when...
The local plasticity characterizing the area around the crack tip affects the elastic strain field area due to the boundary interaction between the two zones. Its effects on the SIF and on the Paris’ Law are known, hence it must be considered in the crack growth monitoring and the fatigue limit estimation. Among the different approaches developed,...
The anisotropy and heterogeneity of composites influence unavoidably the mechanical response of the material to external excitation and the failure mechanisms. As an effect, the mechanical behaviour assessment of composites by means of experimental techniques requires to pay attention to the influence of the specific layup of laminae, viscous prope...
Adhesive joints represent a valid alternative to classical welded and bolted methods, above all for composite materials in which the weight of structures plays an important role for designers. Defects such as debonding of adherents can compromise the correct static and dynamic behaviour of adhesive structures. In this regard, NDT techniques can be...
The stiffness degradation represents one of the most interesting damage phenomena used for describing the fatigue behaviour of composites. A critical aspect of modelling the damage is represented by the simulation of the whole behaviour of the composite and by the assessment of the actual stiffness for the models validation. In this work, the stiff...
Theories for predicting the fatigue behaviour of composite laminates often make strong assumptions on the damage mechanisms that strongly depend on the designed laminate lay-up. In this regard, several physical and empirical models were proposed in the literature that generally require experimental validations. The experimental techniques, such as...
The present research is focused on the use of different non-destructive techniques for detecting damage in CFRP
composite structures obtained by an innovative technological process: Automated Fiber Placement. The component was
a T-joint stringer adhesively bonded to a skin panel. The aim of the present work is to show the capability of these
techni...
In questo lavoro è stata utilizzata la tecnica Termoelastica di Analisi delle Sollecitazioni (Thermoelastic Stress Analysis) per la valutazione del danneggiamento indotto da carichi dinamici su componenti aeronautici in materiale composito. I componenti considerati sono due pannelli in materiale composito CFRP rinforzati da uno stringer. Il monitor...
The techniques present in literature for assessing the endurance limit of materials, involve expensive and long lasting experimental campaign due to remarkable number of specimen being tested. To avoid a time-consuming mechanical characterisation, Infrared Thermography allows to a rapid evaluation of material fatigue behaviour by monitoring the tem...
All the studies on the thermoelastic behaviour of materials, including the revised higher order theory on the thermoelastic effect, are based on several assumptions that limit the application of such theory to the cases of isotropic materials in the presence of uniaxial residual stresses and undergoing uniaxial applied loads. These assumptions lead...
Composite materials are nowadays used in many fields of industry, especially for producing large structural components in many applications ranging from naval to aerospace.
Beside to the capability and versatility of uses, the study of damage in composites is not easy due to the different failure mechanisms that can occur simultaneously or in diffe...
The fatigue crack growth depends on the dissipated energy at the crack tip and in this regard, different analytical and numerical models were proposed by many researchers to describe as the plastic work affect the fatigue material behaviour. Experimental tests can be carried out for evaluating the energy dissipated during the crack growth principal...
Infrared thermography allows an alternative energy‐based approach for studying the fatigue behaviour of materials to better understand damage phenomena. In particular, the methodology of infrared thermography can explain the complex dissipative mechanisms promoted by the input parameters, such as the loading ratio, can rapidly provide information a...
The characterization of the fatigue behaviour of aluminium alloys is still capturing the attention of researchers. As it is well known in literature, for certain alloys, in a specific range of cycles number, the S-N curves do not present any asymptote. So that, problems result in the assessment of the fatigue life. In these conditions, the concept...
A critical aspect of standard test methods for fatigue characterization is that they do not provide any information on heat dissipation in the material and involve very expensive experimental campaigns in time and costs. In recent years, thermographic methods capable of reducing testing time have been developed, also providing more information on d...
Friction Stir Welding (FSW) is a solid-state welding process, based on frictional and stirring phenomena, that offers many advantages with respect to the traditional welding methods. However, several parameters can affect the quality of the produced joints. In this work, an experimental approach has been used for studying and optimizing the FSW pro...
Conventional procedures and methods used for evaluating the fatigue performance of materials require time consuming tests with high number of specimens. In the last years different methods have been developed with the aim to reduce the testing time and then the cost of the experimental campaign. In this regard, thermographic methods represent a use...
In recent years different experimental methods have been experienced to enhance the fatigue characterisation of materials with the aim to overcome the Standard long-lasting tests, i.e. Wohler curve determination. Standard fatigue treatment requires at least 15 specimens being tested to get an estimation of material fatigue limit and it is worth not...
Dissipated energy ahead of the crack tip represents a useful tool to study the fatigue crack growth. In this regard, different analytical and numerical models were proposed in literature to investigate the role of dissipated energy in fracture mechanics and experimental techniques were used to validate them. The experimental measurement of dissipat...
Standards and conventional procedures used for analysing fatigue damage in composite materials involve high experimental campaign costs due to time-consuming tests. This aspect becomes relevant for large structures where the cost of experimental setup tends to rise according to structure dimensions. In this regard, in recent years, efforts to produ...
In this work, the behaviour of two cracked stainless steel AISI 410 and C3FM was studied by means of a new procedure based on thermographic methods. A temperature model in time domain was considered in order to obtain information about the first and the second order harmonic of the temperature signal. Interesting results were obtained in term of po...
Stainless steels are the most exploited materials due to their high mechanical strength and versatility in producing different alloys. Although there is great interest in these materials, mechanical characterisation, in particular fatigue characterisation, requires the application of several standardised procedures involving expensive and time-cons...
Conventional procedures and methods used for obtaining the fatigue performance of materials represent a critical aspect of mechanical characterization because of time consuming tests with a high number of specimens. In the last few years, great efforts have been made to develop a number of methods aimed at reducing testing time and, subsequently, t...
Determination of the Paris Law constants implies the knowledge of both Stress Intensity Factor (SIF) and the crack growth rate (da/dN). In this regard, the crack length and the SIF values can be measured using various methods suggested by literature and proposed by Standards, but most of them require an off-line measurement of the crack with conseq...
In this work, the Thermoelastic Stress Analysis (TSA) technique was used for the monitoring of fatigue crack growth during fracture mechanics tests on stainless steel. In this regards, different methods are used in literature but most of them cannot be applied on real components since they require an off-line measurement of the crack.
Martensitic steels are used in the engineering fields where high temperatures, corrosive environments and high mechanical stress are required. In this work,theThermoelastic Stress Analysis (TSA) technique was used to characterize the fracture mechanics behaviour of twomartensitic stainless steels. TSA technique is proposed both for the monitoring i...
Le tecniche e gli strumenti attualmente disponibili per determinare il limite di fatica dei materiali risultano avere tempi e costi elevati. Il metodo consolidato 'Stair-Case', ad esempio, risulta essere molto oneroso per numero di provini e tempistiche di prova. In quest'ottica, allora, la termografia a raggi infrarossi, rappresenta un valido supp...
Gli acciai inossidabili martensitici sono utilizzati in molti campi dell’ingegneria grazie all’ottima resistenza alle alte temperature, agli ambienti corrosivi e agli elevati stress meccanici a cui possono essere sottoposti. In particolare in questo lavoro sarà utilizzata la tecnica termoelastica di analisi delle sollecitazioni (TSA) per lo studio...
Abstract
Thermography represents an important tool to study fatigue behaviour of materials.
In this work, the fatigue limit of martensitic and precipitation hardening stainless steels has been determined with thermographic methods. Despite their use in corrosive and cryogenic environments, there is a data lack in literature concerning the study of...
Sommario Il limite di fatica rappresenta un parametro importante nella valutazione dei materiali in ambito progettuale sia in condizioni normali, che in condizioni particolari in presenza di alte o basse temperature o ambienti corrosivi. Lo scopo di questo articolo è quello di investigare con metodi termici, il comportamento a fatica di due acciai...
Fatigue behavior is a discriminating feature in choice of steels for extreme conditions such as high or low temperatures and corrosive environments. This is the case of martensitic steels considered in this work, ASTM A182 grade F6NM, and VIRGO 39. These kind of steels are characterized by temperature changes of material related to fatigue damage v...
Fatigue behavior is a discriminating feature in choice of steels for extreme conditions such as high or low temperatures and corrosive environments. This is the case of martensitic steels considered in this work, ASTM A182 grade F6NM, and VIRGO 39. These kind of steels are characterized by temperature changes of material related to fatigue damage v...
Sommario Gli acciai inox martensitici presentano buona resistenza alla corrosione e possiedono elevate caratteristiche meccaniche per la presenza della fase martensitica a temperatura ambiente. Oggetto di questo lavoro è l'analisi del comportamento a fatica e la determinazione del limite di fatica di acciai inossidabili martensitici con metodi term...
Projects
Projects (4)
It is our great pleasure to announce the organization of a Special Session #25 "Infrared Thermography for Structural Health Monitoring" at the 10th European Workshop on Structural Health Monitoring http://www.ewshm2020.com/, Palermo (Italy), July 06-09, 2020.
http://www.ewshm2020.com/special-sessions/#25.
https://www.dropbox.com/s/6fpaq8yubeems3j/EWSHM%20IRT%20Special%20Session.pdf?dl=0
Description:
The rise of anomalous thermal contrasts or temperature changes is a common indicator of an emerging or existing fault in materials and structures. State-of-the-art Infrared cameras are now able to detect and monitor such thermal signatures with high resolution and at high speeds. Moreover, IR cameras operate in real time, in a non-contact way, allow fast and easy setups and can work in various environments.
In the last two decades, many different methodologies have been proposed, trying to exploit the capabilities of modern IR camera systems to enquire the health of a structure/material under natural conditions (Passive Thermography) or induced heating/mechanical stimulation (Active Thermography). Such applications may have different scopes, e.g.: SHM, NDT, material characterisation, structural stress analysis, but they all share in common the attempts to correlate the natural or stimulated thermal response of the structure to its integrity.
Aim of this thematic session is to bring together different experiences, latest developments and case studies on NDT, SHM and Structural Characterisation via Infrared Thermography, in order to foster cross-fertilisation of good practises and ideas for further advances on the use of IR cameras in structural monitoring.
Topics (not restricted to):
Material-based Thermography: material direct or indirect embedded heat sources;
Use of optical and electromagnetic heat sources for active IR NDT;
Evaluation of the Thermoelastic Signal as a damage indicator by means of economic and compact micro-bolometer cameras;
Adaptation of small size and low capital-cost micro-bolometer IR cameras for active IR NDT;
Detection and characterisation of fatigue cracks severity through Thermoelastic Stress Analysis;
Passive thermography for the early detection of equipment flaws and faulty industrial processes.
Conference venue:
The conference will be hosted within the premises of the University of Palermo campus. This is conveniently located near the city center, at 15 minutes walking distance from the Arab-Norman Palermo Itinerary. This itinerary was included in 2015 in the UNESCO World Heritage list http://whc.unesco.org/en/list/1487 .
More info at: http://www.ewshm2020.com/the-venue/
Proceedings
Preparation of a full paper is not mandatory;
Authors who wish to supplement their short abstract with a full paper will have the manuscript included in the Proceedings edited by Springer and indexed in Scopus and Web of Science;
Selected papers will be proposed for a special issue to be published in the Sensors journal;
For more details please refer to the conference website.
Key dates:
Short abstract submission: January 15, 2020
Early bird registration: March 31, 2020
Final manuscript: March 31, 2020
Final program: June 15, 2020
Chairs:
Prof. Giuseppe Pitarresi, University of Palermo, Italy (giuseppe.pitarresi@unipa.it)
Dr. Rosa De Finis, Politecnico di Bari, Italy (rosa.definis@poliba.it)
The goal of the present Special Issue is to show the capability of thermal methods to investigate the fatigue and fracture mechanics behaviour of composites.
https://www.mdpi.com/journal/materials/special_issues/Therm_Fatig_Frac_Compos_Mater