Description:

Webinar

Extreme Mechanics of Soft Functional Materials

Prof. Lihua Jin

Mechanical and Aerospace Engineering, University of California, Los Angeles

Tuesday, August 16, Webinar at 6:00 PM Pacific time

Abstract:

Soft robotics and stretchable electronics are transforming the fields of robotics and biomedical devices, in that they are capable of sustaining large deformation and interacting safely with fragile objects and human beings. Soft functional materials, as the building blocks of soft robotics and stretchable electronics, are typically subjected to extreme mechanical conditions, such as large deformation, cyclic loading, and fracture. In this seminar, I will present our recent progress in modeling and charactering extreme mechanics of soft functional materials. Liquid crystal elastomers (LCEs) are special polymers combining cross-linked elastomers with rod-like liquid crystal mesogens, aligning in a certain direction, called the director. Combining theory and experiments, we show that the directors of a LCE can reorient with stress in a highly rate-dependent manner. We further investigate the coupling between stress and director fields at a crack tip, and observe significant and highly inhomogeneous director rotation, resulting in crack-tip stress and strain distributions of LCEs distinct from those of regular elastomers. Stretchable carbon nanotube electrodes are used in various stretchable electronic devices. When deformed, they show characteristic resistance–strain hysteresis. We use coarse-grained molecular simulations together with experiments to unravel the microstructural origin of the resistance–strain hysteresis. Finally, we study fracture of thin conducting/semiconducting films. We have developed a new testing methodology to measure the fracture energy of free-standing ultrathin films. We further demonstrate that the fracture strain of a thin film is not an intrinsic material property, but can be significantly augmented by tuning interfacial properties.

Speaker Background & Research Interests:

EVENT DATE: Tuesday, August 16

Registration deadline: Monday, August 15, 1:00 PM.

Registration may close earlier than the nominal deadline if capacity is reached.

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Webinar Timing: 6:00 PM.

(Zoom meeting room will open earlier)

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LOCATION:

Anywhere you want, or anywhere you are busy socially distancing, sheltering in place, working, or waiting it all out. Good luck!