research

High-performance stretchable electronics have to utilize high-quality inorganic electronic materials such as silicon, oxide or nitride dielectrics, and metals. These inorganic materials usually crack or yield at very small intrinsic strains, for example, 1%, whereas bio-integrated electronics are expected to at least match the stretchability of bio-tissues (20%) and deployable structure health monitoring networks are expected to expand from wafer scale (several centimeters) to cover macroscopic structures (several meters).

In a pure liquid, molecules touch one another but change neighbors frequently.  External forces cause the liquid to change shape by viscous flow.  Thermal agitation causes  molecules to undergo self-diffusion.  The two phenomena--viscous flow and self-diffusion--often result from a single rate-limiting process:  molecules change neighbors.  This simple picture is amply confirmed by the Stokes-Einstein relation, which links the viscosity and self-diffusivity for many liquids over wide ranges of temperature.

Soft Matters, (2014) Advance article

Recent experiments showed that the Lode parameter, which distinguishes between axisymmetric and shear dominated stress states, has a profound effect on material ductility, especially at low stress triaxiality. Consequently, the theoretical framework for void growth and coalescence is currently being revisited, which often involve performing representative volume element (RVE) calculations. The present study investigates an RVE composed of a cubic unit cell containing a spherical void at its center.

http://hdl.handle.net/10993/12316

http://orbilu.uni.lu/handle/10993/17878

http://hdl.handle.net/10993/17878

3D computational model of graphene reinforced polymer composites is developed and applied to the analysis of damage and fracture mechanisms in the composites. The graphene/polymer interface properties are determined using the inverse modeling approach. The effect of composite structure, in particular, of the aspect ratio, shape, clustering, orientation and volume fraction of graphene platelets on the
mechanical behavior and damage mechanisms of nanocomposites are studied in computational experiments.

We've recently published an open access journal paper that looks at the mechanics of sutures used to repair severed tendons. A homogenization strategy is used to derive effective elastic properties for tendon fibrils and intracellular matrix. We have found that regions of high stress correlate with the regions of cell death (necrosis) that are sometimes observed in patients.

If this is of interest, please feel free to view the paper here.