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Cohen's Mechanics Group

exploring nonlinear solid mechanics

Contact us to inquire about open positions in our group


We are interested in understanding how materials behave when they are pushed to their extremes; whether by imposing large deformations, by applying dynamic loading conditions, or by growth. Closely related to experimental observations, our research exploits analogy with related fields and accounts for complex material response, with the overarching goal to derive theoretical models that can significantly affect our understanding of the observed phenomena, but are still simple enough to be applied in design or characterization of materials. We are a theoretical group with an experimental lab that by basic material fabrication and mechanical testing allows us to make observations and to validate our theories.  

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Material Instabilities

The abrupt behavior of a material at onset of instability may either enounce failure or the triggering of a desired functionality. In our research we ask questions, such as:

What conditions trigger instabilities? How are instabilities exploited in nature? How can we exploit and harness instability for future applications? How can instability be avoided?

These questions have become particularly important with both the growing use of soft and compliant materials in engineering applications and the growing need for protective structures. In both cases materials are expected to perform at large deformations where nonlinear behavior is dominant. 


Extreme Dynamic Loading

From space crafts, cars and buildings to hand-held products like cell phones, tablets and micro-scale electric devices, the ability of a structure to dissipate and mitigate energy upon impact and vibration is imperative to its functionality. Interested in understanding the nonlinear dynamic response of materials, we attempt to answer questions such as:

What are the characteristic velocities that induce shock wave propagation? Should shock waves be avoided in design of protective structures or promoted to enhance energy dissipation?  What happens to soft tissue when it is the presence of explosive pressure gradients?

Answering these questions can lead to the design of more efficient protective structures, to understanding of planetary impacts and cratering, and to understanding the response of the human body to blast.

Material Growth & Chemical coupling

Biological systems exploit growth in fascinating ways. For example, growth can trigger rapid morphological changes and even movement at the level of a single cell. In our research we ask questions, such as:

How do things grow? How does the mechanism of growth lead to development of residual stresses in the grown material? How do those stresses influence the macroscopic properties of the material? And ultimately, how can growth lead to rapid morphological changes and instability?

Our research strives to understand the formation of morphologies observed in nature which can, in turn, be applied in engineering applications.  

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Associate Professor

Tal Cohen

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Postdoctoral Associate

Hudson Borja


Postdoctoral Fellow

Kiana Naghibzadeh


PhD Candidate

Chockalingam Senthilnathan

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PhD Candidate

Xuanhe Li


PhD Candidate

Hannah Varner


PhD Candidate

Joseph Bonavia


Graduate Student

Brendan Unikewicz


Graduate Student - Naval Architecture

Lt Katie Spaeth


Visiting Undergraduate Researcher

Kuldeep Dungarwal

Group Alumni
Dylan Carberry (SM, 2023)
Thomas Henzel (SM, 2022)
Drew Callahan (Undergraduate Thesis, 2021) 
Maxwell Wang 
 (Undergraduate Researcher (UROP
), 2022)
Elijah Van Ryck Groot (Undergraduate Researcher (UROP
), 2022)
Tara Venkatadri (Undergraduate Researcher (UROP), 2022)

Thibault Ghesquiere-Dierickx (MSc, 2022 – EPFL – Thesis advised by Prof. Cohen)
Mrityunjay Kothari (Postdoc, 2022 - Currently faculty at UNH)
Jian Li (Postdoc, 2022 - Currently faculty at Central South University, Changsha, China)
Evelyne Ringoot (MSc, 2020 – Brusseles – Thes
is advised by Prof. Cohen)
Victoire Brault (MSc, 2020 – EPFL – Thesis advised by Prof. Cohen)

Christine Roth (MSc, 2020 – EPFL – Thesis advised by Prof. Cohen)
Shabnam Raayai (Postdoc, 2019 - Currently PI - The Rowland Institute at Harvard)
Rami Abi-Akl (PhD, 2019)
Virginia von Streng (MSc, 2019 – ETH – Thesis advised by Prof. Cohen)
Ismail Honsali (MSc, 2019 - EPFL - Thesis advised by Prof. Cohen)
Jianqiao Wu (SM, 2018)
Zhantao Chen (SM, 2018)
Kelsey Lynn Wittels  (MEng, 2017)

Changyeob Baek (Courtesy member)

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If you  are interested in enrolling for the CEE Graduate Program please go to our Admissions Page

If you would like to apply for a postdoc position in our group, please contact us directly via email (to: and include your CV and recommendation letters.

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