Mechanical and Aerospace Engineering

MAE 297 Seminar – Enrique Lavernia & Zhaodan Kong

Enrique J. Lavernia, Distinguished Professor

Deformation Mechanisms in Bulk Nanostructured Materials and Strategies for Ductility

 

Abstract:

Bulk nanostructured materials and composites have matured into a new class of materials that is being considered in a variety of engineering applications.  The successful synthesis of large-scale nanostructured materials is of technological and scientific significance. From a technological point of view, it will be feasible to obtain engineering materials that retain the structural and chemical attributes of particles/grains in the nanometer size range.  From scientific point of view, large-scale nanostructured materials will permit systematic investigations of the physical and mechanical behavior, as well as novel phenomena.

 

Recently, severe plastic deformation (SPD), which encompasses mechanical alloying in liquid nitrogen (cryomilling) and high-pressure torsion, has emerged as a successful strategy for the synthesis of nanostructured alloys and composites. Results from various groups around the world reveal considerable improvements in the physical performance of a variety of SPD processed metals and alloys. While increases in strength of several 100% are commonly documented, ductility, however, appears to scale inversely with strength in these materials; this behavior has been attributed to limited dislocation activity at these length scales.  This challenge has been addressed via the introduction of additional size scales that facilitate plasticity during deformation.  The concept of a bimodal microstructure has recently been extended into the realm of metal composites with tri-modal microstructural characteristics, to accomplish ultra-high strength values.  In this lecture, published data of cryomilled alloys and composites are reviewed and discussed with particular emphasis on the following topics: recent findings in the area of cryomilled materials; primary consolidation and secondary processing methods; microstructural evolution from nanostructured powders to bulk materials during consolidation; and mechanical behavior of consolidated materials.  The deformation behavior and the underlying mechanisms of cryomilled materials are discussed in an effort to shed light into the fundamental behavior of

ultrafine grained and nanostructured materials.

 

And

 

Professor Zhaodan Kong

Learn From Humans and Bats: A Formal Approach to Sensorimotor Inference and Control

 

Abstract:

A hallmark of research in the control, artificial intelligence, and neuroscience communities is to understand how “perception” should be formally incorporated into feedback control. Various sensorimotor frameworks have been developed at controlling physical systems such as conventional fixed or rotary wing aircraft. However, flying animals such as bats demonstrate remarkable aerial maneuverability and robustness that far exceed those of the aircraft, especially in cluttered environments.  This talk will highlight some of our recent findings on bat sensorimotor behavior.  First, I will discuss how to infer the underlying principles of animal flight performance from data. Then, I will show how to apply the learned principles to the development of bio-inspired robots in confined environments. At the end of my talk, I will briefly discuss some of my work on modeling human guidance behavior and formal verification and synthesis of cyber-physical systems and networked systems.

Date/Time
Date(s) - 11/13/2014
4:00 pm - 5:00 pm

Location
1062 Bainer Classroom

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