1,721,137 research outputs found
Experimental comparison of different innovative joining system for thin walled structures
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Optimisation of a vehicle energy absorbing steel component with experimental validation
No full textThe paper deals with the optimisation of a tapered tubular steel component to be used as an energy-absorbing device in the front structure of a vehicle body. Aim of the optimisation problem is the minimisation of a load uniformity parameter evaluated as the ratio between the maximum and the average crushing loads. The optimisation problem takes into account two design variables describing a tapered geometrical configuration, the diameter of the component at one of its bounds and the tapering length. Two improved geometrical configurations have been found and have been experimentally tested to verify the numerical results with impact velocities up to 10 m/
SVILUPPO DI UNA METODOLOGIA DI SIMULAZIONE DEL PROCESSO DI FORMATURA DEI TUBI PER I FASCI TUBIERI FORZATI NELLE PIASTRE FRONTALI
No full textIl fissaggio dei tubi sui pacchi alettati con cui sono realizzati i grandi scambiatori di calore può essere realizzato mediante un processo meccanico denominato mandrinatura, in cui una ogiva opportunamente sagomata viene spinta all’interno del tubo. L’obiettivo di questo lavoro è lo studio e la messa a punto di un modello agli elementi finiti in grado di simulare al meglio il processo di espansione. Il lavoro è suddiviso in una prima parte sperimentale, in cui vengono caratterizzati i materiali impiegati ed il processo di espansione, ed una seconda parte numerica in cui viene sviluppato il modello sulla base dei dati sperimentali raccolti. Il modello sviluppato permette di valutare l’influenza dei parametri che governano il processo
Experimental evaluation of the strain field history during plastic progressive folding of aluminium circular tubes
No full textThe axisymmetric collapse by plastic progressive folding of a circular tube submitted to axial
loading is considered by an experimental approach. The strain field history is measured by means of
electric strain gages properly placed on the external surface of the tube so that more than one fold is covered
and both axial and circumferential strains are measured. The measured strains are examined both as
time-histories and as a deformation field. The formation and development of circumferential plastic hinges are
pointed out. The strain histories, reported as a function of the displacement of the testing machine cross-head,
are then correlated with the crushing force diagram, leading to a better understanding of the folding mechanics.
In particular, the formation of each fold develops through three subsequent phases: the initialization at the
closure of the previous fold, the flattening of the upper conical surface, and the flattening of the lower conical
surface. While most of the tube wall is pushed outwards of the original cylindrical surface, a portion is pushed
inwards of that surface. Moreover, there is a small portion of the wall that is pulled inward during the
fold initialization and then pushed outward during the fold closure. The analysis of these histories lead to
the validation of the basic assumption of our and other recent kinematical models of the plastic progressive
folding. Copyright © 1997 Elsevier Science Ltd
Investigation on the crushing of circular tubes: theoretical models and experimental validation
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Investigation on the crushing of circular tubes: Theoretical models and experimental validation
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