An apparatus for material testing of a specimen, in particular a battery device. The apparatus includes a specimen holder arrangement with a specimen holder for holding a specimen to be tested, a rod arrangement for moving in direction to the specimen holder for transmitting a mechanical load to the specimen, and an electromechanical actuator for moving at least one of the rod arrangement and the specimen holder arrangement with respect to each other along a longitudinal impact direction. The electromechanical actuator arrangement is configured to adjust the speed to any speed between 0 m/s to 12 m/s between the rod arrangement and the specimen holder arrangement other for transmitting a mechanical load to the specimen.

A dual piezoelectric wire sensor system and a method for non-destructive testing of a cylindrical structure utilizes a pair of H-shaped calipers attached to the cylindrical structure at radial positions ninety degrees apart. Each H-shaped caliper includes two arms and a crossbar connected to and perpendicular to the two arms. A caliper connecter is attached to the first ends of each arm. A wire connecter is attached to the second ends of each arm, between which a piezoelectric wire is connected and stretched. An electrical terminal connects one wire connector to a two-port signal subtractor, which receives signals from the two H-shaped calipers and generates a difference signal. A measurement unit, connected to the two-port signal subtractor, receives the difference signal, performs a frequency analysis, identifies a resonant frequency of an ovalling mode and identifies a stiffness value of the cylindrical structure.