Experimental observations and data analysis of a commercially grade aluminium alloy (6082T6) for large elastoplastic deformation

Large elastoplastic deformation generally occurs in sheet-metal forming processes during stretching, blanking, punching, stamping, bending, bending-unbending, reverse bending and deep drawing. In today’s world, due to very high competition and swift development of products in metal forming industries, there is a growing demand in high precision end products to be manufactured in short duration. It is very essential and important to have a knowledge of an in-depth understanding of material behaviour in all these metal forming steps. Therefore, to predict material behaviour, an accurate material modelling is required by considering the simultaneous effects of strain and strain rate. Classical flow rules are generally used to predict the material behaviour in the post yield range. Overall material deformation can be represented as the change in size, change in shape and their rates. A new generalised relation is developed to represent the material behaviour from elastic range to failure. This relation involves eight material parameters which includes two classical material constants like bulk modulus and shear modulus, two material viscosity terms and four in the form rule which relates elastic strain rate to plastic strain rate. All these material parameters can be obtained from uniaxial tension experiments. The material deformation is 3-D in nature and therefore classical yield criteria is avoided while formulating the relation. Instead, concept of activation energy is used. In the present work, experimental observations and data analysis on the commercial grade aluminium (6082T6) was discussed. The material behavior in the post yield region with new understanding of the material model was presented here for uni-axial loading case. Based on the experimental observations and the results obtained it was found that the both the elastic moduli and the viscosities remain constant throughout the large deformation.