Hydraulischer Tiefungsversuch

Hydraulic Bulge Test Bench (HBT)

In 1999 the self-developed hydraulic bulge test bench (HBT) was put into operation for the first time. Since then, it has been used to characterize both aluminum and steel sheets with regard to their material and forming characteristics. In order to meet the respective requirements and standards, the HTV has been revised, expanded and adapted to existing standards at regular intervals with regard to software and hardware.

Figure 1: Hydraulic Bulge Test Bench (HBT)
Figure 1: Hydraulic Bulge Test Bench (HBT)

Bulge-, Nakajima- and Marciniak-Test

At the test bench, both hydraulic bulge tests (Bulgetest) and Nakajima and Marciniak tests are carried out. An in-situ analysis of the geometry and the sheet thickness of the specimen are carried out. After the experiments, (biaxial) flow curves (bulge test), or limit Forming Limit Curves for characterizing the maximum elongation until material failure can be obtained from the experimental data with high accuracy.

Measuring and control system

The HBT has an interface to the optical measurement system GOM ARAMIS / ARGUS. This allows three-dimensional measurements of the sheet thickness and elongation with high temporal and local resolution. The HBT has a control system which allows to carry out experiments at an approximately constant forming speed and thus to analyse strain-dependent material behavior.

Figure 2: Optical measurement system GOM ARAMIS/Argus
Figure 2: Optical measurement system GOM ARAMIS/Argus

Summary

In summary, the HBT is characterized by the following attributes:

  • Carrying out bulge tests with test temperatures up to 250 °C
  • Determination of the biaxial stress / strain curve by a hydraulic bulge test with optical measuring systems (according to ISO 16808: 2014)
  • Bulge diameter: 240 mm, 100 mm (according to standard)
  • Hydraulically blankholder
  • Optical measurement of sheet elongation and sheet thickness by GOM ARAMIS / ARGUS
  • Measurement of anisotropic material behavior
  • Creation of Forming Limit Curves (FLCs) using Nakajima and Marciniak tests (according to ISO 12004-2: 2008)
  • Stamp diameter:
    • Nakajima: 240 mm, 100 mm (according to standard)
    • Marcinak: 100 mm (according to standard)