Dear members of Laboratoire de Biom'canique du G'boas

Regarding your question about protocol for testing viscoelastic properties
of tendons.
The 10 loading cycles you describe in the testing protocols are used as a
preconditioning procedure, which is intended to stabilize the mechanical
response of the tissue. See Fung (1993) pp. 262 and Viidik (1986) pp. 6.5.
For specific investigations of preconditioning phenomenon in tendons, see
the works by Hubbard and Chun, (1988) and Graf et al., (1994).
It should be noted that the preconditioning procedure is critical for
setting the initial reference of the test because of the shift of the
stress-strain curve to the right that is caused by preconditioning.
It is recommended to precondition the tissue to the maximal strain level
at which the test is preformed (for the stress-relaxation).

Good luck with your work

Ariel Sverdlik
bmesver@tx.technion.ac.il
Department of Biomedical Engineering
Technion - Israel Institute of Technology
ISRAEL

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Fung, Y. C., 1993, "Biomechanics: Mechanical Properties of Living Tissue,"
Springer-Verlag, New-York.

Viidik, A., 1986, "Properties of Tendons and Ligaments," Handbook of
Bioengineering, Skalak, R., and Chien, S., eds., McGraw-Hill Book Company,

Hubbard, R.P., and Chun, K.J., 1988, "Mechanical Responses of Tendons to
Repeated Extensions and Wait Periods," ASME Journal of Biomechanical
Engineering, Vol. 110, pp. 11-19.

Graf, B. K., Vanderby, R. Jr., Ulm, M. J., Rogalski, R. P., and Thielke,
R. J., 1994, "Effect of Preconditioning on the Viscoelastic Response of
Primate Patellar Tendon," Arthroscopy, Vol. 10, pp. 90-96.

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On Mon, 14 Feb 2000 geboas@GEBOAS-ULP.U-STRASBG.FR wrote:

> Good morning,
>
> We are working on the viscoelastic properties of tendons before and after
> freezing. We are looking for 2 types of information: the stress relaxation
> and the ultimate strain to rupture.
> In the literature, the protocols consist usually in 10 cycles of low strain
> with a low strain rate. But we don't understand:
> - Why is a 10 cycles test used by all these teams , rather than a 1
> time/strain test ?
> - Which is initial reference for all these protocols ?
> Initially we thought that we just had to apply the same protocol that was
> applied to a plastic material, but we haven't found a protocol in the French
> standardisation organism guide.
>
> Thank you.
>
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> Laboratoire de Biomécanique du Géboas
> http://geboas.ctw.cc
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>
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