1,721,024 research outputs found
Orientamento delle fibre in polimeri rinforzati con fibre corte: analisi morfologica e microstrutturale di componenti intagliati
No full textPoliammide rinforzata con fibre corte di carbonio: analisi mediante tecniche microtomografiche in contrasto di fase
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Micro-CT investigation on fatigue damage evolution in short fibre reinforced polymers
No full textThe development of predictive models for fatigue behavior of materials is closely related to a quantitative assessment of damage nucleation and propagation phenomena. Conventional methods used for this purpose, such as microscope observations, conventional radiographs, ultrasonography techniques, either are
destructive or do not reach an adequate resolution. Imaging techniques using synchrotron radiation, and
in particular X-ray micro-computed tomography (micro-CT), however, combine the advantages of a nondestructive
technique with a high spatial resolution.
In this paper, damage evolution in samples extracted from PA6.6GF35 specimens subjected to fatigue tests interrupted at different stages of fatigue life is investigated by means of synchrotron radiation micro-CT.
Although preliminary, our results suggest that the application of this technique for micro-voids detection within the glass short fibre polyamide reinforced samples offers unique possibilities of investigating the micro-scale internal structure of the samples but, at the same time, presents several criticalities at different stages of the analyses, ranging from specimen size to set-up configuration and threshold selection.
A frank discussion of the critical issues encountered during the analyses supplements the presentation in an effort to help defining general guidelines for future developments in this field
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
Analisi dell’anisotropia microstrutturale in materiali compositi rinforzati con fibre corte
Full text linkLa microtomografia con luce di sincrotrone si è rivelata una tecnica particolarmente efficace per l’analisi della struttura risultante dalla distribuzione degli orientamenti assunti dalle fibre di rinforzo di compositi rinforzati con fibre di vetro. La ricostruzione dell'immagine tridimensionale ha consentito la visualizzazionedella distribuzione spaziale delle fibre all'interno della matrice polimerica anche nel caso di fibre di piccole dimensioni (diametro medio di 10 micrometri). E' stato quindi possibile misurare le differenze nell'orientamento delle fibre nei differenti strati di un campione utilizzando metodi basati sulla valutazione del Mean Intercept Length (MIL) e del fabric tensor. La tecnica descritta è stata applicata a un campione di poliammide 6 rinforzato con il 30% di fibre corte di vetro ricavato da lastra
Analisi microstrutturale con tomografia a luce di sincrotrone
No full textLa micro-tomografia con luce di sincrotrone è una
tecnica particolarmente efficace per l’analisi della
struttura risultante dalla distribuzione degli
orientamenti assunti dalle fibre di rinforzo di
compositi rinforzati con fibre di vetro.
La ricostruzione dell’immagine tridimensionale
consente la visualizzazione della distribuzione
spaziale delle fibre all’interno della matrice
polimerica anche nel caso di fibre di piccole
dimensioni (diametro medio di 10 micrometri).
È possibile misurare le differenze nell’orientamento
delle fibre nei differenti strati di un campione
utilizzando metodi basati sulla valutazione del Mean
Intercept Length (MIL) e del fabric tensor. La tecnica
descritta è stata applicata a un campione di
poliammide 6 rinforzato con il 30% di fibre corte di
vetro ricavato da una lastra iniettata di testa e da un
provino di geometria più complessa
ELASTICITY OF SHORT FIBRE REINFORCED POLYAMIDE: MORPHOLOGICAL AND NUMERICAL ANALYSIS OF FIBRE ORIENTATION EFFECTS
No full textThe fatigue behaviour of injection moulded short fibre reinforced polymers depends upon fibre orientation, as shown in experiments conducted with notched specimens injected through different injection gates. The different fatigue behaviour is mainly related to the different local elastic properties, as determined by the different fibre orientation patterns, resulting into different strain distributions. In order to quantify the relationship between fibre orientation and elastic constants, the Cell Method was applied to volumes extracted from the specimens, reconstructed by micro-tomography
Fatigue behaviour of short fibre reinforced polyamide: morphological and numerical analysis of fibre orientation effects
No full textFatigue behaviour of short fibre reinforced polyamide: morphological and numerical analysis of fibre orientation effect
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