METALLIC SHELL'S DEFORMATION UPTO LARGE STRAINS

Abstract

Aluminium tubes are studied for energy absorption mechanism. Various fracture studies have been conducted so far. Also tensile testing of aluminum is done widely using Digital Image Correlation method and results obtained were found satisfying previously, this is a different kind of work done for the study of development of strain on the surface of aluminium tubes during their expansion process using a metallic die . Various strains like strain in x direction , strains in y direction ,shear strain ,principal strains and direction of the principal plane in terms of angle in degrees at a point are recorded and plotted along with the load displacement curve during the movement of cross head of INSTRON at a rate of 5mm/mm. The technique used for measurement is that of Digital Image Correlation wh:ch is a non contact measurement technique using high fps cameras. The technique gives strains on the surface of tube for various subsets on the surface and therefore calculations are done on the data obtained for obtaining strains along with the displacement in y direction (i.e. direction of movement of cross head ).The results obtained give a fair idea for each of the samples about the nature of strain development for the experimental conditions in the laboratory and also highlights the effect of other factors like non uniform friction ,eccentricity in loading etc. which can be seen by variations in the strains curves calculated from post processing analysis.