Stavros Gaitanaros’ innovative research focuses on the mechanics of “architected materials” – a a class of materials with exceptional mechanical, acoustic, and thermal properties and unlimited potential in a variety of applications, from space structures and energy storage devices to biomedical implants.

In the interview below, the assistant professor in the Department of Civil and Systems Engineering, fellow in the Hopkins Extreme Materials Institute and the Johns Hopkins Center for Additive Manufacturing and Architected Materials (JAM²), and leader of the Extreme Mechanics of Architected Materials group, shares thoughts on his field, his research program, and the future.

What are the most important problems in your field today?

A wide range of global challenges, from space exploration to modern infrastructure and health, require the design and discovery of new materials with multiple functionalities that provide resilience and sustainability.

Which of those problems are you tackling through your research, and why did you choose them?  

My research focuses on novel lightweight materials with excellent combinations of mechanical, acoustic, and thermal properties, that are derived by the underlying material architecture – a combination of geometry and distribution of matter. Architected materials are characterized by their mesostructure, meaning their morphological features are larger than the atomic scale but still small enough to be classified as a material (one can think of a sponge). Varying the geometric features of this mesostructure and combining them with any typical solid leads to a plethora of material systems with distinct behavior, in a similar manner to material scientists using chemistry and the periodic table to create new alloys. It is actually a concept that nature employs to generate all of its essential structures, from honeycombs and bone to wood and plant stems. It is this unique combination of geometric design and mechanics, applied to both biological and engineered materials, that drew me to this field.

Does your current research seek to answer a fundamental question in science, or does it have potential practical ramifications? Tell us more about that.

My research group is particularly interested in the extreme mechanics of architected materials, which entails their response under large deformations–how they fail, how much energy they can absorb under impact loads, how waves propagate through them, or how they collapse under high temperatures. Our work aims to advance our fundamental understanding of architected materials and develop the necessary computational tools that will enable their systematic design and analysis. Our findings have a far-reaching impact on a broad spectrum of engineering applications, from resilient space structures to soft scaffolds for tissue engineering.

How is your approach to the problem better, more innovative, more promising, or just different than the approach others in your field are using?

The effective blend of different techniques including geometric design, additive manufacturing, computational modeling, theory, and, as of recently, data-driven methods, defines the identity of our group and our unique approach to solving these complex problems.

What has been your most significant finding so far? How about your most surprising finding?

Quantifying significance is tough so I will borrow a passage from Leo Tolstoy’s diaries instead: “There is only one significance, you are a worker. The assignment is inscribed in your reason and heart and expressed clearly and comprehensibly by the best among the beings similar to you. The reward for doing the assignment is immediately within you. But what the significance of the assignment is or of its completion, that you are not given to know, nor do you need to know it. It is good enough as it is. What else could you desire?”

A surprising finding, or at least counterintuitive at first, is that a certain amount of disorder in materials is almost always beneficial (the philosophical extrapolation is rather amusing…).

What other engineer or scientist in your field has influenced you? How?

If I had to choose one, it would be Theodore Von Karman for his enormous body of work in fluid and solid mechanics, and the way he integrated (if not transcended) engineering, applied mathematics, and physics. He is mostly known for his work on aerodynamics but his studies on the mechanics and instabilities of thin plates and shells are, in my opinion, equally important. I would urge any engineering student to find his paper “The engineer grapples with nonlinear problems” or even better read one of his books (if the 5-volume collected works of his seems too heavy of a task).  Von Karman is also an academic ancestor of mine, so I have to acknowledge some level of bias in my choice.

Do you expect to continue working on the same problem five years from now? How about 10? If not, what other research avenues do you anticipate exploring?

My long-term to-do list involves a bunch of diverse problems, from seismic metamaterials and plant mechanics to physics of bubbles, that I really hope I’ll get to explore in the future.

Anything else you want to add?

This Q&A was harder than I initially thought, like a Marcel Proust questionnaire tailored for scientists!

This Q&A was excerpted from the Department of Civil & Systems Engineering. You can read the complete story here.

Lori Graham-Brady, HEMI associate director and professor in the Department of Civil and Systems Engineering and KT Ramesh, the Alonzo G. Decker Professor of Science and Engineering and director of HEMI, were awarded best papers by the Journal of the American Ceramic Society. On October 11, 2022, their winning papers were presented at a special awards symposium at the Materials Science and Technology Technical Meeting and Exhibition in Pittsburgh, Pennsylvania.   

Graham-Brady’s paper is titled, “Fragmentation and Granular Transition of Ceramics for High Rate Loading,” and included co-authors Amartya Bhattacharjee and Ryan Hurley of Johns Hopkins University. 

“Models for the Behavior of Boron Carbide in Extreme Dynamic Environments,” is the title of K.T. Ramesh’s winning paper. Co-authors included: Lori Graham-Brady, Ryan Hurley, Mark Robbins, Amartya Bhattacharjee, Qinglei Zeng, Weixin Li, and Nilanjan Mitra from Johns Hopkins University; William Goddard, California Institute of Technology; Andrew Tonge, DEVCOM Army Research Laboratory; Joel Clemmer, Sandia National Laboratories; and Qi An, University of Nevada, Reno. 

Both papers were the result of research conducted in the Center for Materials in Extreme Dynamic Environments(CMEDE), a center within the Hopkins Extreme Materials Institute. Funded by the DEVCOM Army Research Laboratory, CMEDE research has developed a materials-by-design process for protection materials which have military armor applications.    

After a two-year delay due to COVID-19, the International Conference on Multiscale Materials Modeling (MMM) was held in October 2022 in Baltimore, Maryland. Johns Hopkins University’s Jaafar El-Awady, professor of mechanical engineering, and Somnath Ghosh, M.G. Callas chair and professor of civil and systems engineering, served as chair and co-chair respectively. 

A forum for researchers from academia, national laboratories, and industrial research facilities worldwide with interdisciplinary research backgrounds including mechanics, materials, biomechanics, mechanobiology, advanced manufacturing, mathematics, and computational sciences, the MMM conference is held biennially. It was first held in 2002 in London and the location rotates sequentially between North America, Europe, and Asia.  

The MMM conference is highlighted by four distinguished plenary speakers and eight semi-plenary speakers. The technical program includes 27 technical symposia as well as a dedicated poster session. More than 750 individuals participated in the conference. Conference sponsors included: Johns Hopkins University, George Mason University, Georgetown University, the University of Maryland, and the Hopkins Extreme Materials Institute.  

Congratulations to the recipients of the 2022 HEMI Seed Grants: Prof. Yayuan Liu, Dr. Chao He, and Prof. Dimitris Giovanis!

Liu is an an assistant professor in the Department of Chemical and Biomolecular Engineering and an associate faculty member in the Department of Materials Science and Engineering. Her accepted proposal is titled “Designing Vascularized Porous Electrodes with Enhanced Ion Transport for Battery Extreme Fast Charging.”

He is an associate research scientist in the Department of Earth and Planetary Sciences. His accepted proposal is titled “Spectral signature of prebiotic molecules in Titan’s surface materials.”

Giovanis is an assistant research professor in the Department of Civil and Systems Engineering and Fellow within HEMI. His accepted proposal is titled “Data Driven Uncertainty Quantification for Energetic Materials.”

Each HEMI Seed Grant awards $25,000 to each recipient for the effective award period of September 1, 2022 to August 31, 2023. They are given each year to fund research in fundamental science associated with materials and structures under extreme conditions. All faculty and researchers at the Johns Hopkins University, as well as Applied Physics Laboratory (APL) staff, who can serve as Principal and Co-Investigators are eligible to apply. Learn more about the program here.

Somnath Ghosh, HEMI Fellow and Michael G. Callas Chair Professor in the Department of Civil and Systems Engineering, has been awarded the 2022 Raymond D. Mindlin Medal by the American Society of Civil Engineers (ASCE). Given annually, this medal recognizes an individual’s outstanding research contributions to applied solid mechanics.

Somnath was honored for “outstanding novel contributions to the field of computational mechanics of materials through development of fundamental concepts in spatio-temporal multi-scale, multi-physics modeling of metals, composites and multi-functional materials, and bridging the mechanics and materials communities through strong interdisciplinary leadership.”

Somnath’s research focuses on computational engineering and sciences integrating computational mechanics, computational materials science, and integrated computational materials engineering, with an emphasis on multiscale multi-physics modeling, materials characterization, machine learning, and uncertainty quantification.

He has been invited to accept this award in person at ASCE’s annual Engineering Mechanics Institute Conference, to be held in Baltimore from May 31 through June 3.

Prof. Tamer Zaki and Assistant Prof. Jochen Mueller have been appointed as two of the newest HEMI Fellows.

Zaki is currently a professor in the Department of Mechanical Engineering. He is a winner of the Office of Naval Research Young Investigator Award, is recognized for his innovative theoretical and engineering solutions to technological and environmental challenges created when turbulence meets momentum, heat, and mass.

His work offers novel applications for hydro and aero-dynamics, turbo-machinery, heat transfer, materials processing, and medical interventions with inhaled drug delivery. His research and the work of his lab, Johns Hopkins’ Flow Science and Engineering (FSE), address a classic, complex mechanics problem: Infinitesimal disturbances can cause organized fluid motion to become chaotic.

Mueller is an assistant professor in the Department of Civil and Systems Engineering. His research combines additive manufacturing, functional materials, and computational design in order to create programmable matter.

His research lives at the intersection of science, application and design. Developing novel fabrication processes to enhance the structural complexity, material versatility, and throughput speed in 3D printing, Mueller’s Laboratory for Digital Fabrication and Programmable Matter combines the fabrication processes with computational tools to create or manipulate existing materials and structures in order to change their properties and improve their performance. Mueller’s hands-on background in the aerospace and automotive industries allows him to pursue research projects that have real-world applications, improving materials used in everything from prosthetic devices to lightweight structures.

Earlier this month, four students from high schools around the state of Maryland presented the results of their summer Apprenticeship Program  virtually to an audience of  friends, family, mentors, HEMI Fellows, and representatives from the U. S. Army – Dr. Sikhanda Satapathy (Collaborative Alliance Manager for MEDE CRA) and Mr. Brian Leftridge (U.S. Army Combat Capabilities Development Command).

Adesola Adelegan, Nahuel Albayrak, Kathy Ho, and Emma Liu each were paired with a HEMI Fellow and student mentor to complete their six-week project. During the presentations, each student summarized their research experience, answered questions, and were virtually awarded with a certificate of completion.

During the course of the presentations, HEMI Fellow hosts and mentors had a chance to reflect on each student’s accomplishments. Across the board, the students were lauded for their work ethic and ability to grasp high-level concepts.

“I’m ready to offer her a graduate position,” said Jaafar El-Awady, HEMI Fellow and associate professor in the Department of Mechanical Engineering, when speaking about his group’s intern, Kathy Ho. “She’s done such great, high-level work.”

Echoing Prof. El-Awady’s sentiments was Mitra Taheri, HEMI Fellow and professor in the Department of Materials Science and Engineering, about her group’s intern, Emma Liu. “Emma is underplaying her role in this project. Her research has moved us forward in the state-of-the-art.”

These apprenticeships, sponsored by the Army Educational Outreach Program (AEOP), allows students to gain valuable research experience before attending college. With over 40 sites from which to choose, Johns Hopkins ranks as a very competitive location. Johns Hopkins University received 185 applications for four positions this year.

HEMI is pleased to congratulate Somnath Ghosh – HEMI Fellow, director of the Computational Mechanics Research Laboratory, and M. G. Callas Chair Professor in the Department of Civil and Systems Engineering at Johns Hopkins University – for being named a Fellow of The Mineral, Metals, and Materials Society (TMS).

Ghosh’s research is on computational mechanics with a focus on materials modeling, multi-scale structure-materials analysis and simulations, multi-physics modeling and simulation of multi-functional materials, materials characterization, process modeling, and emerging fields like Integrated Computational Materials Engineering (ICME).

Fellows of TMS are recognized for their outstanding contributions to the practice of metallurgy, materials science, and technology; Fellows must have been members of TMS for at least five continuous years prior to receiving the award.

Learn more about The Mineral, Metals, and Materials Society’s Fellow Award here.

Using funding from both a HEMI Seed Grant and the National Science Foundation, Thomas Gernay, HEMI Fellow and assistant professor in the Department of Civil Systems and Engineering, and colleague Benjamin Schafer, professor in the same department, are investigating if four new types of high-performance steels used in car parts can be cross-functionally used to construct more resilient and sustainable buildings.

The new steels, developed by the automotive industry and used in car bumpers and the steel cage that protects occupants in a crash, improve car handling and fuel efficiency. They are four times stronger than the steel commonly used today, but they are also more expensive to manufacture. Figuring out how to use these steels efficiently in buildings is a priority and a situation that Schafer and Gernay are trying to address.

Gernay and Schafer compiled a comprehensive data set that provides insight into the steels and how they behave under different conditions. Gernay and his team, experts in fire resiliency, tested the steels to gauge their responses to stress, strain, and high temperatures. Schafer’s research centered on the steels’ properties when formed into shapes optimized and appropriate for building construction.

They are currently entering the materials’ temperature data into Gernay’s SAFIR software, which models the behavior of building structures related to fire. Upon completion, the data and hypothetical scenarios will be available for industry use to compare different steels and determine the best material for individual projects.

Learn more about this research here.  

Pictured: Gernay (left) and Schafer (right)