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Karl Kraus
12-28-1995, 04:37 AM
Biomechanical engineers,
In mechanical testing of bone plus-fixator-specimens, stiffness measurements
seem somewhat subjective. There is no distinct yield point as the fixation
and bone tends to sequentially, not catastrophically fail. It has been
suggested by some to derive stiffness from early in the load/displacement
curve, after the toe. My questions are:

1) Is it proper to derive a value for "stiffness" from the early slope of a
load displacement curve in a destructive test?

2) Should stiffness always be derived from a cyclic non-destructive test
under load control?

3) Can any value for stiffness be reported if there is no destinct yeild
point?

Thanks, I'll post responces.

Karl H. Kraus, DVM Em:kkraus@infonet.tufts.edu
Associate Professor of Surgery PH:(508)839-5395
Tufts University School of Veterinary Medicine FX:(508)839-7922
200 Westboro Road "I fix bones is what I do,
North Grafton, MA 01536 I can drill, measure, tap, and screw."