In materials science and solid mechanics, Poisson's ratio (nu) is a measure of the Poisson effect, the deformation of a material in directions perpendicular to the specific direction of loading. The value of Poisson's ratio is the negative of the ratio of transverse strain to axial strain. For small values of these changes, is the amount of transversal elongation divided by the amount of axial compression. Most materials have Poisson's ratio values ranging between 0.0 and 0.5. For soft materials, such as rubber, where the bulk modulus is much higher than the shear modulus, Poisson's ratio is near 0.5. For open-cell polymer foams, Poisson's ratio is near zero, since the cells tend to collapse in compression. Many typical solids have Poisson's ratios in the range of 0.2–0.3. The ratio is named after the French mathematician and physicist Siméon Poisson.
Auxetics are structures or materials that have a negative Poisson's ratio. When stretched, they become thicker perpendicular to the applied force. This occurs due to their particular internal structure and the way this deforms when the sample is uniaxially loaded. Auxetics can be single molecules, crystals, or a particular structure of macroscopic matter.
Paul Mansour Naghdi was a professor of mechanical engineering at University of California, Berkeley.
The Special Achievement Award for Young Investigators in Applied Mechanics is an award given annually by the Applied Mechanics Division, of American Society of Mechanical Engineers (ASME). The Award is presented at the Applied Mechanics Annual Dinner at the ASME Congress. In 2008, this award was renamed to the Thomas J.R. Hughes Young Investigator Award.
Zdeněk Pavel Bažant is McCormick School Professor and Walter P. Murphy Professor of Civil Engineering and Materials Science in the Department of Civil and Environmental Engineering at Northwestern University's Robert R. McCormick School of Engineering and Applied Science.
James Robert Rice is an American engineer, scientist, geophysicist, and Mallinckrodt Professor of Engineering Sciences and Geophysics at the Harvard John A. Paulson School of Engineering and Applied Sciences.
An acoustic metamaterial, sonic crystal, or phononic crystal is a material designed to control, direct, and manipulate sound waves or phonons in gases, liquids, and solids. Sound wave control is accomplished through manipulating parameters such as the bulk modulus β, density ρ, and chirality. They can be engineered to either transmit, or trap and amplify sound waves at certain frequencies. In the latter case, the material is an acoustic resonator.
A seismic metamaterial, is a metamaterial that is designed to counteract the adverse effects of seismic waves on artificial structures, which exist on or near the surface of the Earth. Current designs of seismic metamaterials utilize configurations of boreholes, trees or proposed underground resonators to act as a large scale material. Experiments have observed both reflections and bandgap attenuation from artificially induced seismic waves. These are the first experiments to verify that seismic metamaterials can be measured for frequencies below 100 Hz, where damage from Rayleigh waves is the most harmful to artificial structures.
Jan Drewes Achenbach was a professor emeritus at Northwestern University. Achenbach was born in the northern region of the Netherlands, in Leeuwarden. He studied aeronautics at Delft University of Technology, which he finished with a M.Sc. degree in 1959. Thereafter, he went to the United States, Stanford University, where he received his Ph.D. degree in 1962. After working for a year as a preceptor at Columbia University, he was then appointed as assistant professor at Northwestern University.
Mechanical metamaterials are artificial structures with mechanical properties defined by their structure rather than their composition. They can be seen as a counterpart to the rather well-known family of optical metamaterials. They are often also termed elastodynamic metamaterials and include acoustic metamaterials as a special case of vanishing shear. Their mechanical properties can be designed to have values which cannot be found in nature.
Yonggang Huang is the Jan and Marcia Achenbach Professor of Mechanical Engineering at Northwestern University.
Zhigang Suo is the Allen E. and Marilyn M. Puckett Professor of Mechanics and Materials in the Harvard School of Engineering and Applied Sciences. His research centers on the mechanical behavior of materials and structures.
Alper Erturk is a mechanical engineer and the Woodruff Professor in the George W. Woodruff School of Mechanical Engineering at Georgia Institute of Technology.
Isaac Elishakoff is a Distinguished Research Professor in the Ocean and Mechanical Engineering Department in the Florida Atlantic University, Boca Raton, Florida. He is a figure in the area of mechanics. He has made several contributions in the areas of random vibrations, solid mechanics of composite material, semi-inverse problems of vibrations and stability, functionally graded material structures, and nanotechnology.
Pierre A. Deymier is a researcher in phononics, acoustic metamaterial, and materials science. He is a Professor of Materials Science and Engineering and previously department head at the University of Arizona. He holds appointments with the applied mathematics graduate interdisciplinary program, BIO5 institute, and School of Sustainable Engineered Systems at the University of Arizona. More recently, he has proposed a novel approach akin to quantum computing using the properties of phonons rather than qubits, which he has dubbed "phi-bits" or "phase-bits".
The use of microstructures in 3D printing, where the thickness of each strut scale of tens of microns ranges from 0.2mm to 0.5mm, has the capabilities necessary to change the physical properties of objects (metamaterials) such as: elasticity, resistance, and hardness. In other words, these capabilities allow physical objects to become lighter or more flexible. The pattern has to adhere to geometric constraints, and thickness constraints, or can be enforced using optimization methods. Innovations in this field are being discovered in addition to 3D printers being built and researched with the intent to specialize in building structures needing altered physical properties.
Chiara Daraio is an Italian-American materials scientist and acoustical engineer. She is the G. Bradford Jones Professor of Mechanical Engineering and Applied Physics at the California Institute of Technology.
Eleftherios Ν. Economou is a Greek theoretical physicist and professor emeritus at the department of physics of the University of Crete. He has contributed to various areas of theoretical condensed matter physics, starting with the study of surface plasmons during his thesis in 1969.
L. Catherine Brinson is an American materials scientist who is the Sharon C. and Harold L. Yoh, III Distinguished Professor at Duke University. Her research considers nanostructured polymers and shape-memory alloys. She was elected a Fellow of the American Association for the Advancement of Science in 2020.
Kon-Well Wang is an American academic and engineer, best known for his research work in structural dynamics, especially in the emerging field of adaptive structures & material systems, with applications in vibration & noise controls. acoustic & elastic wave tailoring, shape morphing & deployment, energy harvesting, structural health monitoring, and vehicle and robotic system dynamics. He is the A. Galip Ulsoy Distinguished University Professor of Engineering and the Stephen P. Timoshenko Professor of Mechanical Engineering (ME) at the University of Michigan (U-M).
