By M. Bowman, Sarah Darkwa, and Adam Davison
Dr. Lorna
Gibson, Professor of Materials Science and Engineering at MIT, presented her
research on Biomimicking: Engineering
Design from Natural Structures at ESF on Tuesday, February 14, 2006 as part
of SUNY ESF's Women in Scientific and Environmental Professions Spring Seminar
Series. The ESF Women’s Caucus and the Faculty of Environmental Resources and Forest
Engineering jointly sponsored the seminar.
Dr. Gibson discussed naturally
occurring structures in plants and animals in terms of how they provide flexural
rigidity and resist critical loading. In
other words, how the structures provide both strength and flexibility without
overly increasing weight of the animal or significantly reducing photosynthetic
capacity of the plant.
These structures fall into several categories:
iris and cattail leaves are structural sandwich panels, while plant stems,
bluejay feathers, and porcupine quills are cylindrical shells with compliant
cores. Both types of structures are comprised of fibers or a dense shell on the
outside with a foam core on the inside. Sandwich panels are typically a low-density core material
sandwiched in between two higher modulus plates, which allows for a lightweight
structure with a high rigidity and load capability. Skis and helicopter rotor
blades are similarly constructed to reduce their weight without compromising
their strength. The compliance of the
core material provides resistance in all directions, which allows stems to
resist and prevents bird feathers from kinking.
Other efficient structures for load
resistance are represented by palm trees, bamboo, and woods such as oak. Wood
in particular has a uniform cylindrical structure or “honeycomb” and is one of
the most efficient at resisting loads. The gradient structure of palm trees and
bamboos that allows the stems to grow taller without adding diameter at the
ground level had a large influence on the engineering of bone scaffolds.
The scaffold that Dr. Gibson and
her colleagues are working on is mineralized collagen foam that is comprised of
different gradients. This scaffold is particularly useful for joint implants,
since joints are an interface of bone and cartilage. So far they have tested
their scaffolds in the joints of sheep and goats with very promising results
for human use.
Professor Lorna J. Gibson received
her Bachelor of Applied Science degree in Civil Engineering from the University
of Toronto in 1978 and her PhD from the University of Cambridge in 1981. She
was an Assistant Professor in the Department of Civil Engineering at the
University of British Columbia from 1982-84. She joined the MIT faculty in
1984, where she is currently the Matoula S. Salapatas Professor of Materials
Science and Engineering. Her research interests focus on the mechanical
behavior of highly porous materials with a cellular structure, such as
engineering foams, trabecular bone and scaffolds used in tissue engineering.
She is the co-author, with Professor M.F. Ashby, of the book "Cellular
Solids: Structure and Properties". She has been active in MIT’s gender
equity efforts, chairing the Committee on Women Faculty in the School of Engineering. The next presentation in the Women in
Scientific and Environmental Professions speaker series is March 28. Nancy Grulke, Project Leader, Atmospheric
Deposition on Western Ecosystems and plysiological ecologist, Pacific Southwest
Research Station, will discuss “Air pollution and the Californian
wildfires: an insidious link” at 4 pm in
140 Baker Laboratory. For more
information, visit http://www.esf.edu/womenscaucus.
###
