Indexed on: 01 Jan '74Published on: 01 Jan '74Published in: Anatomy and embryology
Specimens of cartilage from the ribs of cattle were put between the plates of a material-testing machine. They were tested under various conditions of compression. Deformation-time diagrams were applied as input-functions (input-signals). The samples were compressed by constant deformation rates up to certain degrees of deformation. We used periodical deformation-time functions. As, output signals we determined the compressive force in dependency of time. By comparing the input-and the output-functions, we could draw conclusions on the mechanical behavior of cartilage. We achieved the following results: 1. Periodical, trapezoidal deformation-time input-functions by which the cartilage specimen was compressed up to a certain level caused force-time output-signals; relaxation curves were observed constantly during this period. Relaxation decreased from cycle to cycle. In this case the force level at the beginning of each relaxation first decreased rapidly but then only slightly. Both processes seemed to approach a limiting value, i.e. under uniform, periodically repeated and, forced compressions the compressive stiffness was pronounced at first and then became asymptotically smaller. 2. Similar results were achieved under periodical input-signals up to complete unloading. 3. If a trapezoidal input-signal, as given in case one, was generated with additional triangular signals, we obtained a similar output-signal as in case one, but it seemed as if the approximation to a limiting value was reached earlier. 4. If the deformation was kept constant after partial unloading an asymptotic force regain (mechanical, recovery) arose. The complex mechanical behavior of cartilage seemed to accomodate itself efficiently to the manifoldness of mechanical tasks by its viscoelastic properties. These results can be looked upon as a step forward in research on the biorheological mechanism of hyaline cartilage.