SEMINARS

The bio-compatibility and compliance of polymers enable new types of devices that strongly couple chemical and mechanical behaviors. This coupling can be exploited to generate ultra-sensitive bio-sensors and chemically-activated structures in microfluidic systems. These opportunities will be illustrated by experiments which show beam deformation induced by the adsoprtion of the protein avidin onto a thin elastomer film coated with the vitamin biotin. The talk will then describe the mechanics underlying chemo-mechanical interactions between molecular groups adsorbed onto compliant, freestanding films. A framework has been developed which relates the interaction between discrete adsorbed groups and large-deflection film deformation. This model is used to identify the critical molecular interaction parameters required to induce buckling, which can be used to generate ultra-sensitive sensors and valves by ‘tuning’ materials and geometry to the onset of the buckling instability. The final part of the talk will describe progress in experimental characterization of freestanding polymeric microstructures, designed to extract the thermo-mechanical properties and residual stresses arising from fabrication, which play a critical role in device stability and performance.

Moment redistribution refers to the economically advantageous design practice where consideration is provided for the redistribution of the large negative bending moments at interior supports to the less heavily stressed positive bending regions. The degree to which this redistribution occurs is directly related to the member ductility. Thus, in an attempt to insure that adequate ductility exists, present AASHTO specifications restrict both (1) the geometry (slenderness) of members permissible for use with moment redistribution procedures and (2) the maximum amount of moment that may be redistributed. This presentation will focus on research that overcomes these two limitations by directly relating the ductility of steel I-girders to the ductility requirements for moment redistribution. The result of this approach is to remove the majority of the restrictions that currently limit the use of moment redistribution procedures.

Bio: Dr. Jennifer Righman recently assumed the position of Assistant Professor at the University of Delaware after completing her doctoral degree at West Virginia University earlier this year. She has also received master's and bachelor's degrees from West Virginia University. Her past research has focused on behavior, performance, and design issues of steel and polymer bridges.