A method for stress space forming limit diagram construction for aluminum alloys

A method to construct a forming limit corresponding to local necking is sought for aluminum alloy sheet metal. Through the manipulation of data collected from only one uniaxial tension test, a method for the calculation of a stress space forming limit for aluminum sheet metal is offered. Preserving a reasonable level of simplicity, the proposed method features the advantage of not relying upon assumptions about the material properties of the work piece. Such an advantage is realized by measuring the test specimen at the local neck region. Through finite element analysis, the proposed model is shown to be more accommodating to stamping cases where the effective strains exceed the diffuse necking limit. Because the proposed method is designed to circumvent the traditional difficulties associated with the detection and measurement of strains corresponding to local neck regions of aluminum alloys, it is offered as a tool for the formability analyst who desires to employ a reliable stress space forming limit model in their formability analysis. Although the introduction of the proposed method is motivated by the difficulties associated with determining the limiting strains in aluminum sheet metal, it is fully applicable to steel and other material types.