Effect of inhomogeneous tensile deformation of plastic anisotropy

There are several methods leading to precise determination of plastic aniso tropy of materials; all are based on the strain ratio r versus strain epsil on relationship. The present authors propose the description of the variati on of plastic strain ratio during the macroinhomogeneous deformation by the sequence of processes of homogeneous strain in which stable, unchanging de formation mechanism is operating. Two groups of procedures should be displa yed: the first consisting in the determination of strain ratio at several l evels of deformation in the tensile test, and the second one when partial s trains (due to the change of width and thickness of a sample) are related t o the longitudinal strain, The effect of large experimental scatter around the r(epsilon) relationship may be minimized when calculating the fitting f unction based on maximal error procedure and describing the variation of r with epsilon by the hyperbolic relation. The method makes possible the dete rmination of both, the r(o) = r(0) value which describes the plastic anisot ropy of material with a well defined physical meaning, and the r (strain ra tio at a freely chosen strain, e.g. at the limit of uniform elongation: r(a )) which is important for the plastic working technology.