Moment–curvature measurement in thin sheet—part II: yielding and kinking in aged steel sheet

The measurement of the moment–curvature characteristic for thin sheet metal in the elastic–plastic range provides important information which is not readily obtained from the tensile test. Steel sheet which is roll-formed to products such as roofing typically contains a residual stress distribution and is subject to strain ageing; these conditions can be identified from bend tests. The accurate determination of the moment–curvature diagram is not easy as the limiting elastic curvature is large and the magnitude of the moment is small.Part I of this paper describes equipment and data processing which have been developed for this purpose and in Part II, results obtained in sheet which has been progressively aged and stress-relieved are presented.