HC series servo-hydraulic testing machines
Pulsating compressive strength tests (R=0.1) are performed on six specimens with a test frequency of up to 5 Hz. Result: Generation of a Wöhler curve with a number of cycles to crack up to 5 million. This corresponds to approximately 2 years in vivo; approximately 7000 cycles per day. The first runout is confirmed.
In addition to purely axial tensile, compression and flexure tests, a pure or combined torsion load can be applied to spinal systems in compliance with standards including ASTM F1717-9, ASTM F2706-8 or ISO 12189-08.
These tests can be performed under physiological (in-vivo) conditions (for example, tempered saline solution) using a Zwick thermoregulation bath.
For practical statistical evaluations of fatigue tests in the finite life range (high cycle fatigue) and in the transitional range to fatigue strength (long life fatigue), Zwick offers the technical-scientific program SAFD (Statistical Analysis of Fatigue Data).
Testing of spinal implant constructs in a vertebrectomy model
Test arrangement with two vertebral replacement test blocks made of highly cross-linked plastic
The device is also suitable for expulsion tests. Here the expulsion force is determined by positioning the implant between two machined blocks and applying a defined axial preload. A transverse load, which determines the expulsion strength, is then applied to the implant by a testing actuator via a compression die until the implant is expelled. The maximum force determined defines the expulsion force. The Amsler HC Compact servo-hydraulic testing machine features compact design and extremely low noise, providing an optimum solution for testing vertebral body replacements in any laboratory when used in conjunction with the test fixture for torsion tests on vertebral bodies.
Tests with the Zwick test fixture for torsion tests on vertebral body replacements