Society of Physics Students &
Department of Physics Seminar
Strain Rate Effects in Biomaterials -
Understanding Accident Injuries and Designing Treatments
Prof. Nikhil Gupta
Composite Materials and Mechanics Laboratory
Polytechnic Institute of New York University
High speed deformation conditions are relevant to military as
well as to civilians. Armors may encounter ballistic impact and
blast, while automobiles may crash at high speeds. Understanding
the response of armor and automotive materials at such loading
rates is as important as understanding their effect on humans. The
response of soft and hard tissue to mechanical loading is
significantly different. The hard tissue, femur bones, is selected
for initial studies.
This presentation is aimed at discussing the high strain rate
compression test technique and the results obtained on rabbit femur
bones. The bones were also characterized under quasi-static
compression to enable comparison with the high strain rate results.
The quasi-static compressive moduli of the epiphyseal and
diaphyseal regions were measured to be in the range of 2–3 and 5–7
GPa, respectively. The strength at high strain rate was measured to
be about twice the quasi-static strength value. A large number of
small cracks initiated on the specimen surface close to the
incident bar. Coalescence of crack branches leading to fewer large
cracks resulted in specimen fragmentation. In comparison, the
quasi-static failure was due to shear cracking. The difference in
the failure mode based on strain rates is important for designing
protective gears and developing treatment protocols.
Come join us! Food and drinks will be served.