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jwu66
08-14-2002, 11:03 PM
Dear colleagues,

Preconditioning is a procedure to load and unload the soft tissues several
times before the data collection. There were many great discussions on the
preconditioning of soft tissue in YC Fung's early work (e.g. Biorheology,
1973, vol 10, 139-155). The purpose to perform the preconditioning, as I
understand, is to achieve more repeatable testing results. Although the
preconditioning has been routinely applied in soft tissue tests, I am
skeptical about the necessarity to perform such a procedure. If a soft
tissue is considered to be a viscoelastic material, and the purpose of the
testing is to determine the viscoelastic material properties, the mechanical
behaviour (e.g., stress relaxation behaviour) is varied completely after the
preconditioning. In fact, the preconditioning behaviour can be predicted
using a viscoelastic model.

My question is:

1. Should preconditioning always be applied in any soft tissue tests:
tensile/compressional, stiffness, fatigue, stress relaxations tests ?

2. If the purpose of the preconditioning is to obtain a repeatable testing
result, can we do a large number of tests, instead of do preconditioning?

Thanks in advance for your inputs,

John Z. Wu, Ph.D.
NIOSH/CDC
National Institute for Occupational Safety and Health
Email: jwu@cdc.gov

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