Ultrasonic Measurement of Rotation of Principal Axis of Plastic Anisotropy and Change of Elastic Stiffness of Prestrained Polycrystalline Sheet Metal.

It is desired to develop the identification scheme of the principal axis of plastic anisotrypy of polycrystalline sheet metal to the improvement of calculation accuracy of formability. Elastic anisotropy is due to texture, it is same cause with plastic anisotropy, therefore, plastic anisotropy can be measured through phase velocity measurement of an ultrasonic wave. The rotation of the principal axis and the change of elastic constants of a sheet metal for press forming during plastic deformation are identified with the phase velocity of Rayleigh wave. It is demonstrated that the principal axis rotates independently of the material fiber.