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Caratterizzazione di giunti CDW in alluminio mediante test non distruttivi e meccanici
Full text linkModellazione strutturale di schiume di alluminio a celle aperte
No full textNel presente lavoro si espone uno studio numerico circa la modellazione di una schiuma di alluminio a celle aperte. In particolare, si esamina una schiuma M-pore di densità 10ppi soggetta ad una prova di compressione. Il modello numerico realizzato si basa sulla generazione casuale di nodi corrispondenti ai vertici di celle Kelvin e sulla unione di ognuno di tali vertici con i quattro punti più vicini. L’obiettivo è quello di riprodurre la struttura irregolare di una schiuma a celle aperte. Il confronto con i dati sperimentali a disposizione ha permesso di individuare il modello ottimale dopo aver analizzato una serie di parametri quali: il numero delle celle all’interno di un volume di riferimento, il raggio dei legamenti, la dimensione della cella elementare
Geometric modelling of metallic foams
Full text linkPurpose:
The aim of this work is the development of a procedure able to model the highly irregular
cellular structure of metallic foams on the basis of information obtained by X-ray tomographic
analysis.
Method:
The geometric modelling is based on the feature “pore” characterized by an ellipsoidal shape.
The data for the geometric parameters of the instances are obtained with a methodology
which is driven by the pore volume distribution curve. This curve shows how much the cells,
whose diameter belongs to a given dimensional range, contribute to the reduction of the total
volume.
Result.
The presented methodology has been implemented into a CAD tool consisting of a Matlab
routine identifying the instances of the feature “pore” and a CATIA’s macro modelling the
closed cells foam.
Discussion & Conclusion:
The CAD model developed for two types of closed cells foams approximates by considerable
accuracy both the density and the volume distribution of the real foams
Studio del comportamento a trazione di giunti di testa in schiuma metallica
No full textQuesto lavoro descrive lo studio sperimentale svolto per valutare la resistenza a trazione di alcuni giunti in schiuma di alluminio ottenuti mediante diverse tipologie di collegamento, sia mediante
bulloni che adesivi a base di resina epossidica. Sono state considerate diverse tipologie di disposizione dei bulloni e per ogni prova è stato ricavato il valore della forza massima necessaria per la rottura del collegamento. Le migliori prestazioni meccaniche si ottengono con il collegamento realizzato mediante due piastre coprigiunto e resina epossidica. Nel caso di collegamenti mediante bulloni, il carico trasmesso aumenta al crescere del numero di bulloni
Geometric modelling of metallic foams
Full text linkPurpose - The aim of this work is the development of a procedure able to model the highly irregular cellular structure of metallic foams on the basis of information obtained by X-ray tomographic analysis. Design/methodology/approach - The geometric modelling is based on the feature "pore" characterized by an ellipsoidal shape. The data for the geometric parameters of the instances are obtained with a methodology which is driven by the pore volume distribution curve. This curve shows how much the cells, whose diameter belongs to a given dimensional range, contribute to the reduction of the total volume. Findings - The presented methodology has been implemented into a CAD tool consisting of a Matlab routine identifying the instances of the feature "pore" and a CATIA's macro modelling the closed cells foam. Originality/value - The presented methodology allows to obtain in an automatic way the CAD model of the complex structure of closed cell aluminium foam approximating by considerable accuracy both the density and the volume distribution of the real foams
Characterization of aluminium alloy capacitor discharge joints using non destructive and mechanical testing
No full textThis work considers the possibility to apply the improved hybrid Capacitor Discharge Welding process (CDW), based on projection Welding principles, to aluminium alloy Al 5754.
The innovative aspects are the effective possibility to weld aluminium alloys with CD Welding process and establish the mechanical weld characteristics and defects presence as
function of the technological parameters.
Intrinsic CDW process characteristics need to be investigated on the base of interaction between the technological aspects and the related mechanical properties. The geometrical and
technological factors are combined to improve the welding efficiency and reduce defects size.
In order to assess the technological parameters, visual and ultrasonic inspection of the most significant welded joints were performed and room temperature tensile and fatigue tests were
executed to verify the welding results
Aluminium foams structural modelling
No full textThe aim of this work is the development of microstructural numerical models of metallic foams. In particular, attention is focused on closed cell foam made of aluminium alloy. By means of a finite elements code, the material cellular structure was shaped in different ways: firstly the Kelvin cell, with both plane and curved walls; finally an ellipsoidal cell defined by random dimensions, position and orientation has been adopted as base unit. In order to validate the foam numerical models, static tests were performed to obtain the typical stress–strain curves and then compared with the numerical analysis results
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