Keynotes/Lectures
Ramathasan Thevamaran:
Embedded Material Intelligence: From Impact Mitigation to Tailored Wave Dynamics by Engineered Dissipation
DATE/TIME:
Monday, June 2, 2025 | 9:00 a.m.
ABSTRACT:
Materials with superior specific-energy absorption, -strength, and -modulus are critical for lightweight protective applications such as helmet liners, sports gears, electronic packaging, and vibration absorbers. The typically used viscoelastic polymers, however, suffer from pronounced temperature and strain-rate dependencies that affect their performance in extreme environments. In this lecture, we present a novel hierarchical material system—vertically aligned carbon nanotubes (VACNTs)—whose tunable structure with multiscale structural organization and non-viscoelastic energy dissipation provide unprecedented opportunities to overcome those challenges and achieve robust multifunctional bulk properties. Additionally, by exploiting size-confined synthesis of architected VACNTs and interactive morphology from the mesoscale architected elements, we show that their specific-modulus, -strength, and -energy absorption can be improved synergistically at ultra-low-densities. Finally, we demonstrate that the strain-rate-independent mechanics of VACNTs elicit a return-point memory effect which we exploit to design layered composites with embedded material intelligence for amplitude-dependent wave limiters. Traumatic brain injury prevention during collisions, protective cartridges for planetary landers, and extreme vibration control in air and spacecraft are some of the many applications that could benefit from the novel thermo-mechanical properties of VACNT-based material systems.
Ramathasan Thevamaran is the Bernard A. and Frances M. Weideman Associate Professor of Mechanical Engineering at the University of Wisconsin - Madison. He received his B.Sc.Eng.(Hons.) (2008) in Civil Engineering from the University of Peradeniya - Sri Lanka, and his M.S. (2010) and Ph.D. (2015) in Mechanical Engineering from Caltech. Prior to joining UW-Madison as an Assistant Professor in 2017, he was a Postdoctoral Research...
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Daniel Rittel:
Static and Dynamic Fracture Mechanics of Printed Aluminum Lattices
DATE/TIME:
Tuesday, June 3, 2025 | 11:00 a.m.
ABSTRACT:
With the advent of metal printing technologies, the creation of lattices that was extremely arduous until now, has become much easier, allowing for a variety of parameters such as lattice unit cell, struts thickness among others.
While the mechanical response of lattices, under both static and dynamic conditions, has and still is extensively studied mostly for energy absorption purposes, the fracture mechanics of the said lattices has been widely overlooked.
Experiments were carried out for two notched lattice geometries (diamond and diagonal) that were tested under quasi-static and dynamic (impact) loading using one point impact experiments. This type of loading allows not only mode I but also mode II testing of the notched specimens.
The salient characteristics of the fracture process will be reported, together with a systematic comparison between static and dynamic failure modes. In addition, the combined use of our ultra-high speed and the thermal cameras will be shown to complement the visual information by thermal measurements that are characteristic of the failure process.
Prof. Daniel Rittel, formerly the Zandman Chair in Experimental Mechanics and head of the Materials Mechanics Center, is an emeritus professor in the Faculty of Mechanical Engineering at Technion. D. Rittel was the Clark B. Millikan Visiting Professor in Aeronautics (2007) at Caltech where he holds a Visiting Associate position. He was the incumbent of a Catedra de Excellencia at UC3M (Madrid) in 2012 and 2019, where he is now...
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