buletinul institutului politehnic din iaşi - Universitatea Tehnică ...

Bul. Inst. Polit. Iaşi, t. LVIII (LXII), f. 4, 2012 207
In the deformation process, the network geometry, previously mapped,
will change shape, providing important information on the efforts direction or
displacement. In this case the specimen surface was printed with a circular
network with interleaved patterns.
To achieve experimental tests we have designed and developed a
hydraulic inflation device (Fig. 3). The equipment is distinguished both by
manoeuvrability and ability to easily change the active plate type used in the
deformation process. Thus, the facility includes a total of three interchangeable
active boards with circular, square and elliptical shape.
a b
Fig. 3 – Hydraulic device
a – assembly; b – section view (1 – lower body; 2 – port-mold plate (sliding); 3 – upper
body; 4 – elastic membrane; 5 – fixing screw; 6 – active plate (or mold plate)).
2.2. Condition Imposed for Experimental Test
For conducting experimental research, aimed to determine FLD, three
types of metallic materials were considered. Thus, we choose the most
commonly materials used in Romanian industry: steel (wide strip steel B2),
brass (CuZn37) and aluminium (Al 99.5%).
The factors considered to be influencing factors of the system are the
active plate shape and the thickness of specimen used for data determination.
Thus, for the experimental test we used specimens with thickness of 0.5 mm, 1
mm, 1.5 mm, depending on the studied material. It should be noted that the
design of the hydraulic stand allowed varying active plate between the rounded,
elliptical and square plate.
After conducting the preliminary experiments it was found that, for
aluminium specimen with 0.5 mm thickness, material fracture occurs at very
low pressures and deformation. Thus, we take into account the introduction, for
further experiments, of specimens with 1.5 mm thickness.