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BULETINUL INSTITUTULUI POLITEHNIC DIN IAŞI
Publicat de
Universitatea Tehnică „Gheorghe Asachi“ din Iaşi,
Tomul LVIII (LXII), Fasc. 4, 2012
Secţia
CONSTRUCŢII DE MAŞINI
DETERMINATION OF FORMING LIMIT DIAGRAMS USING
HYDRAULIC BULGING TEST
Received: October 13, 2012
Accepted for publication: October 15, 2012
BY
OVIDIU NIŢĂ ∗ and VASILE BRAHA
„Gheorghe Asachi” Technical University of Iaşi,
Department of Machine Manufacturing Technology
Abstract. Estimation of technological possibility of obtaining a piece
by stamping can be done most effectively by using the forming limit
diagrams (FLD). The aim of this paper was to determine the deformation
limit diagrams, for three metallic materials commonly used in Romanian
industry, using hydraulic bulging test. Also, the authors wanted to
highlight the influence of blank thickness or the deformation path on
FLD.
Key words: forming limit diagrams, FLD, bulging test etc.
1. Introduction
Sheet metal deformability expresses their ability to be plastic deformed
and to take a given form, without defects in the specimen (Banabic, 1992). One
of the most popular methods used for assessing the capacity of sheets
deformation is the forming limit diagrams (FLD) method. Basically, forming
limit curves mark off (inside a rectangular system of axes) the acceptable
deformations from the zone where deformation turns the specimen in to scrap
(Fig. 1a) (Marciniak, 2002; Banabic, 2005).
Forming limit diagram is a graph obtained by plotting the evolution of the
main deformations (ε1, ε2) in plane sheet, when fracture and necking occurs
(Fig. 1b). As a result of using two limit deformation criterions (necking and
fracture) the FLD have two types of forming limit curves (FLC): one for
∗ Corresponding author: e-mail: ov_nita@yahoo.com