College Park, Maryland June 6 - 10 , 2004
T3-C3 (4:30 PM): Residual Stresses in Deep Drawn Cups as Standard Specimens for Springback Characterization
T. Gnaeupel-Herold (NIST Center for Neutron Research; Department of Materials Science and Engineering, University of Maryland), T. J. Foecke (NIST Metallurgy Division), H. J. Prask (NIST Center for Neutron Research)
Springback is the elastic shape change of a sheet metal part after forming upon removal of the die. It is created by residual stresses which, in turn, originate from plastic strains that are inhomogeneous both within the sheet plane and through thickness. One focus of current efforts for a more accurate prediction of springback are the measurement and modeling of residual stresses in deep drawn cups which are considered as promising candidates to become standard specimens for springback characterization. From neutron and synchrotron strain measurements the residual stresses were found to vary non-linearly in all three directions. The most pronounced changes were found in the through-thickness direction with similar general features regardless of material or sheet thickness.
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