AME Department Seminar

Speaker: L. Lamberson, Postdoctoral Research Scholar at the Center for Advanced Metallic and Ceramic Systems. Johns Hopkins University.

Talk Title: Cracks, Dynamics & the Piezoelectric Effect

Abstract: While a large amount of data is available on the properties and behavior of piezoelectric ceramics subjected to small strains and electric fields as used in conventional sensor and actuator applications, little data exists which contributes to a basic understanding of the behavior of piezoelectric ceramics subjected to high-rate impulsive loading. This particular loading regime plays a critical role in defense applications, specifically for blast mitigation and ballistic protection since numerous armor ceramics such as silicon carbide and aluminum nitride exhibit piezoelectric properties. In addition, piezoelectric materials are also valued for their ability to be utilized as a single-shot, high-energy power supply (or switch) when pulverized, as well as in energy resource recovery applications. In order to utilize these materials ‘smart’ ability, the frequency-time response plays a crucial role in failure, and depends on both the mechanism of polarization, as well as the effect of damage on polarization.

This talk focuses on high strain rate dynamic electromechanical experiments (103 s-1) conducted on single crystal α-quartz, single crystal silicon carbide and aluminum nitride. The results exhibit unexpected trends stress-charge behavior during damage evolution. Specifically, when quartz is undergoing extensive and irreversible dynamic brittle fracture under a compressive stress impulse of up to 2 GPa, the effective piezoelectric stress coefficient increases from loading to unloading. The experimental results are examined in the framework of the theory of linear piezoelectricity and compared to traditional continuum damage models, in order to understand the role of increasing crack density on electroelastic properties.

Biography: Dr. Leslie Lamberson has an appointment as an Assistant Professor in the Mechanical Engineering and Mechanics Department at Drexel University, and is presently a Postdoctoral Research Scholar at the Center for Advanced Metallic and Ceramic Systems at the Johns Hopkins University. Her research encompasses high strain rate material system behavior. Leslie received her BS in Aerospace Engineering from the University of Michigan, and MS in the same discipline from the Georgia Institute of Technology. Working with Professor Ares Rosakis, she completed her Ph.D. in Aeronautics from the California Institute of Technology examining hypervelocity impact induced dynamic fracture behavior of brittle polymers.

Host: Professor Veronica Eliasson

More Info: http://ae-www.usc.edu/seminars/index.shtml#upcoming

Location: Seaver Science Library (SSL) - 150

Audiences: Everyone Is Invited

Contact: April Mundy

Event Link: http://ae-www.usc.edu/seminars/index.shtml#upcoming