Researchers at Pacific Northwest National Laboratory have demonstrated experience in predicting formability of lightweight alloys, including magnesium sheet. A heated limiting dome height (LDH) testing system, in conjunction with digital image correlation (DIC), is used in the evaluation of sheet alloys. This test enables the development of a forming process window for sheet alloys and helps determine the fracture limit curves, resulting in a forming limit diagram (FLD). The LDH test simulates the common failure strain states in sheet metal forming processes. In addition, information generated from the LDH can be used to generate grain orientation and strain evolution. This type of information provides useful validation of the predictive models being developed.
LDH tests can be conducted on sheets at room temperature up to 250°C.
In this test, biaxial strain can be obtained with a standard dome punch. However, different strain paths, ranging from uniaxial tension through plane strain to equibiaxial stretching, can be covered using specimens with different widths and the Marciniak punch and die. The dome height at a maximum load (near failure) is used as a measure of formability.
Facilities are available for both government and private (proprietary) project work.
Name: Eric Nyberg
- Rohatgi A, DR Herling, and EA Nyberg. 2009. "Characterization and formability of continuous-cast AZ31B Magnesium alloy sheets," Magnesium Technology 2010, ed. SR Agnew, NR Neelameggham, EA Nyberg and WH Sillekens, pp. 573-578. TMS , Warrendale, PA.