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Constitutive Models for Soft Tissue
Mechanical behavior of soft tissue such as articular cartilage are strongly dependent on the microstructure of their collagen fiber network, as well as their chemical composition. I have developed micromechanics-based constitutive laws in a poroelastic framework where fluid flow is governed by a chemical potential gradient. Fiber level effects such as pre-tension and buckling can be easily incorporated through a force-displacement law for individual fibers
Biomedical Adhesives
Phase separation, swelling, accelerated creep and degradation are common to polymeric tissue adhesives under simultaneous mechanical load, solvent diffusion, and temperature fluctuations. I have characterized phase separation for a commercial dentin adhesive mimic using chemometrics and developed a poroelastic model for wet adhesives . The model was able to predict swelling of the polymer adhesive phases. I am currently working on improving the poroelastic models beyond conventional poroelasticity to account for the size of the pores ranging from macro to molecular scales. As a first step, I have developed an experimental technique to study the binding between the pore water and polymer chains using FTIR spectroscopy.
Atomic to Continuum Bridging
It is well known that displacements at the discrete level do not follow the Cauchy-Born rule for disordered systems or systems with microstructure. But even in perfect crystals with a single atom in the unit cell, thermal vibrations can be a source of dynamic non-affinity. At high temperatures, this non-affinity contributes significantly to the stress and becomes a crucial factor in multiscale modeling of nanocrystals at high temperatures. Our approach proposes local definitions of deformation measures and their stress conjugates which capture the contribution to free energy from this non-affinity.
I am developing local definitions of stress at the atomic scale to reconcile the homogenized continuum behavior obtained from MD simulation with the statistical description of rubber elasticity for a classical coarse-grained polymer model. I then aim to study phase transitions in crosslinked polymers under simultaneous action of mechanical stress, solvent diffusion and temperature.