Composite materials research
Composites research in our laboratory includes extremal composites in the context of viscoelasticity, maximal stiffness, thermal expansion and piezoelectricity, as well as the biomechanics of biological materials such as bone, tendon, ligament as composites (see links at right); moreover, dental composite resins for tooth fillings and composites for aircraft. Negative Poisson's ratio can be achieved in foams and lattices (composites with one phase as empty space) or in composites with two solid phases or in materials in the vicinity of phase transformations.
Aircraft composites: moisture ingression
Moisture ingression was studied in several composite sandwich panels. Polymer matrix composite materials have been used in a variety of applications in the aerospace industry. These materials exhibit excellent mechanical properties and low density. However, the epoxy resins used in such systems usually absorb water or moisture. Variations in temperature can cause a substantial degradation of the resin's mechanical properties and these deleterious effects can be exacerbated when the resin is also exposed to moisture. Since exposure to fluctuating temperature and moisture is inevitable in aerospace applications, considerable research effort has been devoted to study the mechanism by which epoxy resin composites absorb and transmit (ingress) moisture and the effect of moisture on their mechanical properties.
Cise, D. M. and Lakes, R. S. "Moisture ingression in honeycomb core sandwich panels", Journal of Materials Engineering and Performance, 6, 732-736, (1997).
Cise, D. M. and Lakes, R. S. "Moisture ingression in honeycomb core sandwich panels: Directional aspects", J. Composite Materials , 31, 2249-2263, (1997).
Dental composite resins are used for filling teeth. The matrix of these composites is polymeric. Creep deformation can be problematical. References are provided in the context of biomaterials .
Strength and ductility of magnesium alloys can be improved by the addition of fine grains of silicon carbide.
Cao, G., Choi, H., Konishi, H., Kou, S., Lakes, R. and Li, X., "Mg-6Zn/1.5%SiC nanocomposites fabricated by ultrasonic cavitation-based solidification processing", Journal of Materials Science, 43, 5521-5526, (2008).
De Cicco, M., Konishi, H., Cao, G., Choi, H., Turng, L. S., Perepezko, J. H., Kuo, S., Lakes, R. S., and Li, X., "Strong, Ductile Magnesium-Zinc Nanocomposites", Metallurgical and Materials Transactions A, 40, (12), 1073-5623 (Print) 1543-1940 (Online) Dec. (2009). get pdf
Nimityongskul, S., Jones, M., Choi, H., Lakes, R., Kou, S., and Li, X., Grain refining mechanisms in MgAl alloys with Al4C3 microparticles, Materials Science and Engineering: A, 527(7-8), 2104-11, (2010). get pdf
Asphalt as a composite
We have begun a link with the asphalt group to study the performance of asphalt as a composite material.
Lakes, R. S., Kose, S., and Bahia, H., "Analysis of high volume fraction irregular particulate damping composites", ASME Journal of Engineering Materials and Technology, 124, 174-178, April (2002).