Abstract
The purpose of this paper is to derive mathematical stress-strain expressions which can be applied to arbitrary strain paths of 590N steel and aluminum alloys (A5052BD-H34, A6061BE-T6, A6063S-T5, A6063S-T6, A6N01BE-T5, A6N01BE-T6, A7003S-T5, A7N01S-T5, A7N01S-T6) from experimental results. Cyclic stress-strain relationships of aluminum alloy were almost the same as normal mild steels. The mathematical expressions consist of the three components, namely, the skeleton part, the softened part and the unloaded part. The curves of the softened part and the skeleton part can be expressed as a function of only one factor : that is plastic strain experienced in a preceding half cycle. The experimental curves of stress-strain relations can be followed by the proposed empirical rules with good accuracy.
