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Lightweight Design Center

Material characterization and -modeling for crash-adapted lightweight designs

Zwick1.jpgTo ensure crash properties in the construction and design of vehicles, the use of computer-aided design methods has already established itself in the early phases of product development. In order to guarantee a high quality of the results of the simulation methods used, the material models must meet the high requirements that the calculation of the structures, which are often anisotropic and subjected to high strain rates in the event of a crash, entails.
The selection of suitable material models and the experimental determination of the strain rate- and temperature dependent material parameters is part of the work of the lightweight design group at the Chair of Engineering Design at FAU. The simulation results obtained can be validated with crash tests at component level.

Servo-hydraulic high-speed test rig

Zwick2.jpgWith the Zwick HTM 5020 servohydraulic high-speed testing system, tensile and puncture tests can be carried out with up to 50 kN load and 20 m/s haul-off speed. This corresponds to achievable strain rates of up to 1000 s-1. For force evaluation of the tests lasting only a few milliseconds, the input signals are recorded and provided at high frequencies of up to 8 MHz. In combination with the GOM Aramis HHS optical evaluation technology, precise stress-strain curves can be created, which form the basis for parameter optimization of material models.

Temperature chamber

Zwick3.jpgAn integrated temperature chamber allows tests from -60° to 150 °C. This allows the test conditions to be adapted to subsequent use and temperature-dependent material behavior to be investigated.

Stereoscopic camera system

Zwick4.jpgThe Photron Fastcam stereoscopic camera system is used for the evaluation of component and sample deformation to ensure accurate, non-contact measurement value acquisition. It enables recording rates of up to 750,000 images per second and can be used on both the high-speed inspection system and the drop tower. By means of gray value correlation the occurring strain is determined locally and compared with simulation results.

Drop tower

Zwick5.jpgA drop tower is available for component testing and validation of material models. It can be used for impactor tests at impact speeds of up to 5 m/s. The maximum transferable energy is 200 J. The fracture patterns and deformations of the test and simulation can then be compared and, if necessary, adjusted. This ensures that the material data determined from tensile tests on test specimens also provide correct results at component level.