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Fatigue crack propagation through adhesively bonded stiffened panels: a model to describe the skin crack behavior underneath the stiffeners
No full textAdhesively bonded stiffened panels can provide
the best damage tolerance proprieties if compared
to the conventional integral and riveted
panels. Bonded panels can, indeed, take big advantage
by the long fatigue crack propagation
periods through the skin underneath the bonded
stiffeners. To exploit the aforementioned benefit
of bonded panels for safe and weight effective
structures, reliable prediction models taking into
account the fatigue crack propagation under the
bonded stiffeners have to be provided.
A well known analytical literature model, developed
for the damage tolerance characterization
of patch repairs, was implemented and subsequently
validated by fatigue crack propagation
test results concerning wide stiffened panels.
The implemented model confirmed to be a
reliable and effective method for the damage tolerance
design optimization of thin-walled bonded
structures
Damage tolerance of adhesive bonded stiffened panels: experimental and analytical investigation of the fatigue crack propagation underneath the stringers
No full textOn the basis of well-known literature, an analytical
model was developed by the authors to provide reliable
predictions on the fatigue propagation of cracks growing through
the skin underneath adhesively bonded stringers of aeronautical
stiffened panel. In order to exploit the significant damage
tolerance proprieties of adhesively bonded stiffened panels it is
indeed fundamental to take into account the slow fatigue crack
growth under the bonded stringers, currently completely neglected
as a consequence of the limits of the employed prediction tools.
The correlation between the model predictions and experimental
fatigue crack propagation test results of wide stiffened panels
permitted to validate the model and to provide a deep insight into
the mechanisms involved during the skin crack propagation under
the bonded stringers of fatigue loaded panels.
The implemented model confirmed its reliability in describing the
fatigue skin crack propagation under the bonded stringers, but
phenomena that can occur during this propagation phase, as
adhesive delamination that can develop around the advancing
crack tip and the fatigue failure of the bonded stringer must be
taken into account in order to obtain reliable predictions
The effect of laser shock peening on fatigue behaviour of aluminium alloy 6082-T6
No full textLaser Shock Peening (LSP) is an innovative surface treatment technique used to improve the fatigue performances of metallic components. This technique uses a high power density laser pulse to create a compressive residual stress field in the treated component; the established residual stress field is at the base of the fatigue performance enhancement. In this work, thick 6082-T6 aluminum alloy specimens were LSP treated and subsequently fatigue tested. An increase of fatigue life and surface hardness was encountered in respect to the untreated material. Besides confirming the results present in the literature, this experimental campaign served to confirm the capability of the University of Bologna to perform in-house an advanced surface treatment such as Laser Shock Peening
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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