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DD

DD: Deep Drawing
Definition:Mixed tensile and compression deformations of metallic sheets to build a hollow body or continued mixed tensile and compression deformations to built a hollow body with a smaller diamaeter [DIN 8584-3].
Explanation:The basic principle of DD can be seen in figure below showing the case of a cupping test. The blank sheet is fixed by the drawing ring and the blank holder. During the deformation, the material continuously flows through the gap between them, forming a cup. During the process, two important parameters controlling the deformation process are (i) the ratio between the punch and the sheet and (ii) the blank holder force. By varying these values, a range of validity can be achieved whether a desired deformation can be realized under specific conditions.

During industrial applications, complex parts with a large range of different local strains are produced. The cupping test is an important tool to find possible designs and processing windows, as well as select materials.
Picture /
Figure /
Diagram:

(a) Schematic setup for deep drawing. (b) Drawn cup. (c) FEM simulation results of a drawn cup.
SFB-Link:The mixed deformation mode during the DD process results in a complex stress triaxility, which is used to investigate material failure modes as delayed cracking (→DC) which can be seen in high Mn steels. Furthermore, cupping tests are commonly used to evaluate the deformation capabilities of sheet materials, for instance, in the automotive sector which is a potential application of high Mn steels.
References:DIN 8584-3: Manufacturing processes forming under combination of tensile and compressive conditions Part 3: Deep drawing - Classification, subdivision, terms and definitions, 2003.
Bleck W. et al.: Materials Characterization, Textbook for Students, 2012.