Biaxial material testing machine

Planar-biaxial experiments testing play an important role in materials modeling since, for incompressible-isotropic materials such as rubber, it can provide a complete characterization of the material properties.

Our custom-made setup for planar-biaxial materials testing was specifically designed for soft materials and biological tissues. Four hydraulic actuators are mounted on a positioning plate installed on a vibration isolation table. The primary configuration aligns the actuators in 90° angles for planar biaxial testing.

The actuators can be driven individually in displacement or force control-mode, whereas the loading profile can be defined by the operator. The actuators exhibit an interface to mount test-specific custom-built clamps. A biochamber can be installed for testing of biological tissues under physiological conditions, i.e. in a saline bath at 37°C. A video extensometer is used to determine the in-plane specimen displacement field from which the deformation and strain field can be computed.

We use this set-up also for uniaxial stress and pure shear experiments [24p], [26p].

Technical data/features

4 hydraulic actuators

> 200 bar operating pressure

> 100 mm stroke

> 2.5 kN force capacity o loading rate up to 200 Hz

available load cells: 100 N, 2 kN

Software that allows to design complex test protocols (each actuator can be controlled individually or phase-controlled against a set of actuators)

Heated saline bath for environmental control: room temperature up to 45°C

Grip interface to mount test-specific clamps

Contactless specimen deformation measurement (digital image correlation)

04/23/13 | Manfred Maurer | ZfM | ETH