New book: R. S. Lakes, Composites and Metamaterials, July (2020).
Book outline
Case studies for class
aircraft safety,
bio-med
Humor: error message
haiku.
Research summary
In our laboratory we conceptualize, synthesize and characterize materials with extreme and unusual physical properties.
We have developed new materials with reversed properties, including the first 3D materials with a negative
Poisson's ratio (
auxetic).
We have developed the first materials with arbitrarily large magnitudes of positive or negative
thermal expansion. Zero thermal expansion is also attainable.
We have developed the first extreme materials based on negative
stiffness inclusions in composites. Recently such materials have been called
metamaterials.
Materials which undergo phase transformation are of interest in the context of viscoelastic damping and of negative stiffness. Composite materials
stiffer than diamond over a temperature range have been demonstrated in the lab. These are also called
metamaterials.
We investigate the freedom of natural and synthesized materials to behave in ways not anticipated in elementary
continuum representations, to ameliorate stress concentrations, and to attain physical properties of much higher magnitude than anticipated from standard theories. Designed Cosserat solids have been made by 3D printing. These materials exhibit reduced stress concentrations compared with classical elastic materials.
The first experimental determination of the full set of Cosserat elastic constants for a material was done in our laboratory.
We have made the first designed
2D chiral elastic material
and the first 3D designed and
3D printed
Cosserat chiral elastic material. These have been called
chiral metamaterials. Recently we have observed effects of chiral elasticity in the gyroid lattice.
We study materials with heterogeneous structure, including natural viscoelastic composites such as
bone,
ligament, tendon and wood, as well as synthetic composites, biomaterials, and cellular solids with structural
hierarchy.
Viscoelastic materials are of particular interest as high performance damping materials and as practical materials which undergo creep in industrial settings. We determine viscoelastic properties including internal friction, dependence on strain rate, and creep over eleven orders of magnitude of frequency and time, with no need for temperature shifts. We have developed materials and structures that offer extreme viscoelastic damping.
We also study practical composite materials such as dental composites for tooth restorations and aircraft composites in the context of damage resistance and damage tolerance as well as moisture ingression.
Piezoelectric composites and lattices, chiral elastic lattices, as well as thermoelastic composites and lattices are presently of particular current interest. We pursue basic research as well as applied research for industry. Industrial research has included high temperature performance studies of alloys for small engines, improved shoe insoles, and advanced dampers.