MEASUREMENT AND ANALYSIS OF THE BAUSCHINGER EFFECT OF SHEET METALS SUBJECTED TO IN-PLANE STRESS REVERSALS

摘要

A novel material testing apparatus for measuring the Bauschinger effect of sheet metals has been developed. The testing apparatus enables continuous in-plane tension/compression tests of a sheet specimen without buckling. The thickness of the sheet specimen can be as thin as 0.4mm. Cyclic stress-strain curves of several sheet metals have been measured precisely; the materials used are austenitic stainless steel sheet, low carbon Al-killed IF-steel sheet and 6000-type aluminum alloy sheet. The maximum number of cycles of stress reversals is fifteen and the maximum strain amplitude is 0.04. In order to formulate the cyclic stress-strain relations, Ohno's constitutive model of cyclic plasticity is applied. It is found that the calculated cyclic stress-strain curves are in fair agreement with the observed ones for all the test materials.