The hydraulic bulge test bench is used to characterize both aluminum and steel sheets with regard to their material and forming characteristics.
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 HBT has been revised, expanded and adapted to existing standards at regular intervals with regard to software and hardware.
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 forming limit curves for characterizing the maximum elongation until material failure can be obtained with high accuracy from the experimental data.
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 for conducting experiments at an approximately constant forming speed and thus analyzing strain-dependent material behavior.
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)
- Hydraulic 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)
