Theory and experiment are presented to show that an interface between two soft materials under compression can form creases, a type of bifurcation distinct from wrinkles. While creases bifurcate from a state of flat interface by a deformation localized in space and large in amplitude, wrinkles bifurcate from a state of flat interface by a deformation nonlocal in space and infinitesimal in amplitude. The interfacial creases set in at a lower critical compression than interfacial wrinkles, but higher than surface creases. The condition for the onset of interfacial creases is scale-free, and is calculated in terms of elastic moduli, pre-strains and applied strains.
5th International Conference of Mechanics of Biomaterials and Tissues
8-12 December, Sitges, Spain
To check the program or to register, go to http://www.mechanicsofbiomaterials.com/conference-Program.html
An exhibition will run alongside the conference sessions. Companies already registered as exhibitors include: Asylum Research, Biomomentum, Bose, CSM Instruments, PCS Instruments.
by Y. Li, N. Kaynia, S. Rudykh and M. C. Boyce
Massachusetts Institute of Technology
Two Ph.D. positions will be immediately available in the
Department of Mechanical Engineering at Temple University, Philadelphia, PA,
US. Both positions will start in Fall, 2013. The research program will focus on
mechanics of soft composite materials and its novel application in healthcare,
lightweight nano-composites for energy absorption, and renewable energy
harvesting, etc. The research will involve a combination of experimental
measurements, analytical modeling, and numerical simulation methods. We are
looking for self-motivated and creative candidates (preferable graduate
Postdoctoral Research Associate at University of Pennsylvania :: Modeling of nanomaterials and soft materialsSubmitted by Dibakar Datta on Fri, 2013-03-01 17:52.
A postdoctoral position with primary focus on molecular dynamics simulations is available immediately at Shenoy Research Group under the direction of Prof. Vivek B. Shenoy . We are looking for a strongly motivated candidate to work on modeling of nanomaterials and soft materials. The ideal candidate will have a background in materials science/computational physics with expertise in molecular dynamics simulations with LAMMPS or other packages. This individual will have the opportunity to be directly involved in complimentary experimental investigations, both at Penn and our collaborators in industry.
When a material is soft or the size of the material is small, the effect of surface energy on its deformation can be significant.The importance of surface energy on the deformation of a structure could be evaluated by the magnitude of a dimensionless number, called elastocapillary number: γ/μL, where γ is surface energy density, μ is shear modulus and L is the characteristic length of the structure. Many intriguing phenomena of surface energy induced deformation of even instabilities have been observed in different experiments. In this journal club, I want to initiate a discussion on how surface energy may affect mechanical instabilites in soft materials.
On behalf of the organizing committee, I cordially invite your participation in Symposium on Mechanics and
Physics of Soft Matter, as part of the 13th Pan-American Congress of Applied Mechanics (PACAM XIII), to be held in Houston, Texas, May 22-24, 2013.
I have a postdoc position in the dept. of MAE in UCSD, starting from Feb. 2013.
The research will be on the mechanics of soft materials and biomaterials, the design and fabrication of soft active structures and
mechanics of energy materials.
People with experimental background on experimental mechanics, materials fabrication and bioengineering is perferred.
Please send CV with reaserach experience and publications to the email: email@example.com, if you have interest.
Dielectric elastomer actuators under equal-biaxial forces, uniaxial forces, and uniaxial constraint of stiff fibersSubmitted by tongqing.lu on Fri, 2012-05-04 00:35.
A membrane of a dielectric elastomer deforms when a voltage is applied through its thickness. The achievable voltage-induced deformation is strongly affected by how mechanical loads are applied. Large voltage-induced deformation has been demonstrated for a membrane under equal-biaxial forces, but only small voltage-induced deformation has been observed for a membrane under a uniaxial force. This difference is interpreted here theoretically. The theory also predicts that, when the deformation of a membrane is constrained in one direction, a voltage applied through the thickness of the membrane can cause it to deform substantially in the other direction. Experiments are performed on membranes under equal-biaxial forces and uniaxial forces, as well as on fiber-constrained membranes of two types: a dielectric elastomer membrane with carbon fibers on both faces, and two dielectric elastomer membranes sandwiching nylon fibers. The experimental observations are compared with the theory.
NSF Summer Institute Short Course on Materiomics—Merging Biology and Engineering in Multiscale Structures and Materials
Location: Massachusetts Institute of Technology, LeMeridien Hotel (former Hotel@MIT)
Chair: Markus J. Buehler, Massachusetts Institute of Technology (mbuehler@MIT.EDU)
Dates: May 30 (Wednesday) morning to June 1 (Friday) evening, 2012
Course Objectives: Theme-based introduction into emerging science at the interface of engineering and biology
Welcome to February 2012's Journal club, which will include a discussion on elastic instabilities for form and function. Not long ago, the loss of structural stability through buckling generally referred to failure and disaster. It was a phenomenon to be designed around, and rarely did it provide functionality*. The increasing focus on soft materials, from rubbers and gels to biological tissues, encouraged scientists to revisit the role of elastic instabilities in the world around us and inspired their utilization in advanced materials. Now the field of elastic instabilities, or extreme mechanics, brings together the disciplines of physics, mechanics, mathematics, biology, and materials science to extend our understanding of structural instabilities for both form and function. In this journal club, we're going to look at research on the wrinkling, crumpling, and snapping of soft or slender structures.
We have several open postdoc positions, to be filled immediately.
The first project is focused on thermal management. The project involves the computational and theoretical analysis of graphene/graphite-metal nanocomposites and experimental work carried out by other team members. We are looking for a strong person with background in thermal and mechanical properties of materials, preferrably with background in molecular simulation.
For the other projects we are looking for candidates with expertise in mechanics of materials. Our projects are specifically focused on molecular and coarse-grain modeling of deformation and failure of soft biological materials and include a focus on collagen, spider silk, amyloid materials and other biomaterials.
A previous work suggested a critical condition to form surface creases in elastomers and gels. For elastomers, the critical condition seems to have closed a gap between experimental observations (e.g., by bending a rubber block) and the classical instability analysis by Biot. For gels, however, experiments have observed a wide range of critical swelling ratios, from around 2 to 3.7. Here we present a linear perturbation analysis for swollen hydrogels confined on a rigid substrate, which predicts critical swelling ratios in a similar range.
I finished the grad course on Mechanics of Soft Materials. It took 14 weeks with 2 academic hours per week and it covered the following topics: 1 Tensors 2 Kinematics 3 Balance laws 4 Isotropic elasticity 5 Anisotropic elasticity 6 Viscoelasticity 7 Chemo-mechanical coupling 8 Electro-mechanical coupling.
I attach the class notes and I will be grateful for the remarks, corrections, and criticism from iMechanicians.