CoMMa Laboratory
Computational Mechanics of Materials
A comma connects. So do we — across scales, across disciplines.

The CoMMa Lab, led by Ritwik Bandyopadhyay from the Department of Applied Mechanics at IIT Delhi, investigates how advanced engineering alloys deform, accumulate damage, and fail. We develop computational and probabilistic frameworks to uncover the physical mechanisms behind these phenomena — from the scale of individual grains to the scale of real material systems. We welcome collaborations based on mutual interest and complementary expertise.

Research

Advanced engineering alloys represent some of the most microstructurally complex material systems studied in modern mechanics of materials. They are engineered to operate under challenging conditions in terms of stress, temperature, and environment, where the physical mechanisms governing deformation, damage, and failure are far from fully understood. Every new generation of such materials introduces new microstructural architectures, sometimes new deformation mechanisms, and often new failure modes that challenge existing theoretical and computational frameworks. Understanding the behavior of these materials across length scales is a rich and largely open scientific problem.

Our research sits at the boundary between fundamental mechanics of materials and computational mechanics of materials. We ask questions that are scientifically open and intellectually consequential.

What we work on

Our research is organized around four interconnected questions:

How does damage begin?

Fatigue has been studied for over a century and a half, yet crack initiation remains a scientifically unresolved problem. The reason is not lack of effort — it is that materials science never stands still. As researchers develop new alloys, new processing routes, and new fabrication technologies, entirely new microstructures emerge, each bringing its own deformation and damage mechanisms. What governs crack nucleation in a legacy material is not the same as in a next generation alloy.

We are interested in uncovering the physical mechanisms by which damage initiates and evolves and how various microstructural features such as grain boundaries, inclusions, phase interfaces, and crystallographic texture influence these. This remains a fundamental open question in the mechanics of materials.

What history does a material carry?

Every material system carries a hidden imprint of its processing history — residual stress, lattice distortion, and dislocation substructure accumulated during processing. These internal states profoundly influence subsequent deformation and damage behavior, and incorporating them into physically consistent computational models is both scientifically non-trivial and essential for mechanistically faithful predictions.

We work on understanding and quantifying this internal state across multiple length-scales, and on developing rigorous methods to initialize it within our computational frameworks.

Can we bridge scales?

Microstructure-sensitive models are mechanistically attractive and scientifically essential for uncovering the physics of damage at lower length scales. However, extending their reach across the multiple length and time scales relevant to real material systems is one of the central scientific challenges of the field.

To this end, we explore scale-bridging strategies — reduced-order modeling, surrogate modeling, and computationally efficient simulation approaches — as intellectually interesting problems in their own right. Physics-informed machine learning models play an important role here, offering a scientifically grounded means of enabling physically informed predictions across scales.

How much do we know, and how confidently?

This question has a different character depending on where in the modeling hierarchy one sits. For high-fidelity microstructure-sensitive models, the challenges primarily lie in parameter uncertainty and calibration — model parameters are difficult to measure directly, and their uncertainty propagates through computationally expensive simulations in ways that are hard to characterize.

For reduced-order and surrogate models, the challenges shift more toward model-form uncertainty, loss of physical fidelity, and the difficulty of validating predictions in regimes where experimental data is sparse. In both cases, uncertainty quantification, verification, and validation are not peripheral concerns but scientifically substantive problems that sit at the core of our research.

Why it matters scientifically

The mechanics of materials has passed through empirical, analytical, and computational phases of development. The questions that remain open — how damage nucleates, how internal state evolves, how grain-scale physics connects to macroscopic response — are not merely technically difficult. They are genuinely scientifically deep, in the sense that answering them requires new physical understanding, not just better numerical methods. Each new class of advanced alloys reopens these questions in a new context, ensuring that this remains a scientifically fertile and consequential field of inquiry for the foreseeable future.

Team

Group Leader

Faculty
Ritwik Bandyopadhyay

Ritwik Bandyopadhyay

Ritwik holds a PhD from Purdue University, an MTech from IIT Kanpur, and a BE from IIEST Shibpur. He currently serves as an Assistant Professor in the Applied Mechanics Department of IIT Delhi, following a postdoctoral fellowship at Purdue University. Read more →

Email: ritwik [at] am.iitd.ac.in

PhD Students

1 current member

Vishabjeet Singh

Research areas: smooth particle hydrodynamics; dynamic, anisotropic, and multi-physics fracture in solids.

External supervisor: Prof. Md Rushdie Ibne Islam, Ocean Engineering and Naval Architecture, IIT Kharagpur.

MTech Students

3 current members

Dinesh Kumar

Co-supervisor: Prof. Sankalp Tiwari, Applied Mechanics, IIT Delhi.

Kalpesh Shirish Kulkarni

Co-supervisor: Prof. Rajdip Nayek, Applied Mechanics, IIT Delhi.

Pranav Sharma

BTech Students

2 current members

Arnav Jain

Co-supervisor: Prof. Arpit Agrawal, Applied Mechanics, IIT Delhi.

Sarthak Gupta

Co-supervisor: Prof. Arpit Agrawal, Applied Mechanics, IIT Delhi.

MTech Students

Alumni archive

Chandrakesh Chauhan

Batch: 2024–26

Placement: LG Electronics

Co-supervisor: Prof. Rajdip Nayek, Applied Mechanics, IIT Delhi.

Sourabh Borkar

Batch: 2024–26

Placement: Trident Group

Co-supervisor: Prof. Rajdip Nayek, Applied Mechanics, IIT Delhi.

Voleti Durga Prasad

Batch: 2023–25

Placement: Serentica Renewables

Nitin Kumar

Batch: 2022–24

Placement: Maruti Suzuki

Vivek Gopakumar

Batch: 2022–24

Placement: Pratt & Whitney

BTech Students

Alumni archive

Eslavath Vidhath Veerendra Pamar

Batch: 2026

Gaurav Verma

Batch: 2026

Aditya Agrawal

Batch: 2025

Kanishk Singh

Batch: 2025

Biosketch

Education

  • PhD (Aeronautics and Astronautics) — Purdue University (2020)
  • MTech (Mechanical Engineering) — Indian Institute of Technology Kanpur (2016)
  • BE (Mechanical Engineering) — Indian Institute of Engineering Science and Technology, Shibpur (IIEST, erstwhile BESU) (2013)

Professional Experience

  • Assistant Professor [October 2022 – current], Department of Applied Mechanics, Indian Institute of Technology Delhi, India
  • Postdoctoral Fellow [June 2020 – June 2022], School of Aeronautics and Astronautics, Purdue University, USA

Awards & Recognition

  • Young Faculty Incentive Fellowship, 2022–2025 (Awarded by IIT Delhi)
  • AAE Teaching Scholarship, 2019 (School of Aeronautics and Astronautics, Purdue University)
  • Lynn Fellowship, 2016 (Purdue University — computation science and engineering research)
  • Institute Assistantship, 2014–2016 (IIT Kanpur, based on GATE score)
  • Scheme of Scholarship for College and University Students, 2010–2013 (MHRD, Government of India)
  • Merit cum Means Scholarship, 2011–2013 (IIEST Shibpur, based on academic performance)
  • Travel Grant for Conference, 2012 (Indo-US Center for Research Excellence on Fabrionics — ASME IMECE 2012)
  • Travel Grant for Summer Internship, 2012 (Indo-US Center for Research Excellence on Fabrionics — UC Irvine)
  • Summer Research Fellowship, 2011 (Indian Academy of Sciences, Bangalore)

Publications

For a continuously updated list, please see Ritwik's Google Scholar profile.

Journal Articles
  1. 15Bandyopadhyay, R., Stopka, K. S., & Sangid, M. D. (2024). Initializing intragranular residual stresses within statistically equivalent microstructures for crystal plasticity simulations. Journal of the Mechanics and Physics of Solids, 184, 105529.
  2. 14Mackey, B. T., Bandyopadhyay, R., Gustafson, S. E., & Sangid, M. D. (2023). Grain interactions under thermo-mechanical loads investigated with coupled crystal plasticity simulations and high-energy X-ray diffraction microscopy. Acta Materialia, 257, 119166.
  3. 13Krishnamoorthi, S., Bandyopadhyay, R., & Sangid, M. D. (2023). A microstructure-based fatigue model for additively manufactured Ti-6Al-4V, including the role of prior β boundaries. International Journal of Plasticity, 163, 103569.
  4. 12Gopalakrishnan, S., Bandyopadhyay, R., & Sangid, M. D. (2022). A framework to enable microstructure-sensitive location-specific fatigue life analysis of components and connectivity to the product lifecycle. International Journal of Fatigue, 165, 107211.
  5. 11Gardner, P. F., Noone, S. J., Bandyopadhyay, R., Park, J-S., Walker, K., & Sangid, M. D. (2022). Damage tolerant assessment of laser clad repairs of coarse grain Ti-6Al-4V. Experimental Mechanics, 62, 1421–1436.
  6. 10Bandyopadhyay, R., & Sangid, M. D. (2021). A probabilistic fatigue framework to enable location-specific lifing for critical thermo-mechanical engineering applications. Integrating Materials and Manufacturing Innovation, 10(1), 20–43.
  7. 9Bandyopadhyay, R., Gustafson, S. E., Kapoor, K., Naragani, D., Pagan, D. C., & Sangid, M. D. (2021). Comparative assessment of backstress models using high-energy x-ray diffraction microscopy experiments and crystal plasticity finite element simulations. International Journal of Plasticity, 136, 102887.
  8. 8Waddell, M., Walker, K., Bandyopadhyay, R., Kapoor, K., Mallory, A., Xiao, X., Chuang, A. C., Liu, Q., Phan, N., & Sangid, M. D. (2020). Small fatigue crack growth behavior of Ti-6Al-4V produced via selective laser melting: In situ characterization of a 3D crack tip interactions with defects. International Journal of Fatigue, 137, 105638.
  9. 7Bandyopadhyay, R., Prithivirajan, V., Peralta, A. D., & Sangid, M. D. (2020). Microstructure-sensitive critical plastic strain energy density criterion for fatigue life prediction across various loading regimes. Proceedings of the Royal Society A, 476(2236), 20190766.
  10. 6Bandyopadhyay, R., & Sangid, M. D. (2019). Crystal plasticity assessment of inclusion-and matrix-driven competing failure modes in a nickel-base superalloy. Acta Materialia, 177, 20–34.
  11. 5Bandyopadhyay, R., Prithivirajan, V., & Sangid, M. D. (2019). Uncertainty quantification in the mechanical response of crystal plasticity simulations. JOM, 71(8), 2612–2624.
  12. 4Bandyopadhyay, R., Mello, A. W., Kapoor, K., Reinhold, M. P., Broderick, T. F., & Sangid, M. D. (2019). On the crack initiation and heterogeneous deformation of Ti-6Al-4V during high cycle fatigue at high R ratios. Journal of the Mechanics and Physics of Solids, 129, 61–82.
  13. 3Bandyopadhyay, R., Rotella, J., Naragani, D., Park, J. S., Eff, M., & Sangid, M. D. (2019). Residual strain analysis in linear friction welds of similar and dissimilar titanium alloys using energy dispersive x-ray diffraction. Metallurgical and Materials Transactions A, 50(2), 704–718.
  14. 2Maiti, S., Bandyopadhyay, R., & Chatterjee, A. (2018). Vibrations of an Euler-Bernoulli beam with hysteretic damping arising from dispersed frictional microcracks. Journal of Sound and Vibration, 412, 287–308.
  15. 1Bandyopadhyay, R., Maiti, S., Ghosh, A., & Chatterjee, A. (2018). Overhead water tank shapes with depth-independent sloshing frequencies for use as TLDs in buildings. Structural Control and Health Monitoring, 25(1), e2049.
Conference Proceedings

(*Presenting author)

  1. 16Bandyopadhyay, R., Kapoor, K., & Sangid, M. D.* (2024). Initializing grain and sub-grain scale residual stress in crystal plasticity simulations. TMS 2024, Orlando, FL, US.
  2. 15Mackey, B. T.*, Bandyopadhyay, R., Gustafson, S. E., & Sangid, M. D. (2024). Crystal plasticity investigation of microstructural thermo-mechanical fatigue damage mechanisms under various phasing profiles leveraging high-energy X-ray diffraction microscopy. TMS 2024, Orlando, FL, US.
  3. 14Sangid, M. D.*, Gopalakrishnan, S., & Bandyopadhyay, R. (2023). Designing aerospace components with model-based definitions to enable location-specific tailoring of properties. ICME 2023, Orlando, FL, US.
  4. 13Mackey, B. T.*, Bandyopadhyay, R., Gustafson, S. E., & Sangid, M. D. (2023). Grain scale deformation study of a nickel-based superalloy under thermo-mechanical fatigue utilizing crystal plasticity simulations and high-energy X-ray diffraction microscopy. TMS 2023, San Diego, CA, US.
  5. 12Bandyopadhyay, R.*, Gustafson, S. E., Sharma, H., Kenesei, P., & Sangid, M. D. (2022). Modeling and experimental characterization of intragranular residual stress, statistically stored and geometrically necessary dislocations. TMS 2022, Anaheim, CA, US.
  6. 11Mackey, B. T.*, Bandyopadhyay, R., Gustafson, S. E., & Sangid, M. D. (2022). Grain scale deformation study of a nickel-based superalloy under thermo-mechanical fatigue utilizing crystal plasticity simulations and high-energy x-ray diffraction microscopy. TMS 2022, Anaheim, CA, US.
  7. 10Gopalakrishnan, S.*, Bandyopadhyay, R., & Sangid, M. D. (2022). A framework to enable location-specific analysis of components by incorporating microstructural information during the product design cycle. TMS 2022, Anaheim, CA, US.
  8. 9Bandyopadhyay, R.*, & Sangid, M. D. (2020). Linear friction welding of Ti components: investigation of residual stress and fatigue performance. TMS 2020, San Diego, CA, US.
  9. 8Bandyopadhyay, R.*, & Sangid, M. D. (2020). Competing mode of failure predictions in a Ni-based superalloy using crystal plasticity finite element simulations. TMS 2020, San Diego, CA, US.
  10. 7Caccia, M. R.*, Bandyopadhyay, R., Morrissey, C., McCormack, C., Strayer, A., Sangid, M. D., Scofield, G., & Sandhage, K. H. (2019). Zirconium carbide/refractory metal composites produced by the displacive compensation of porosity (DCP) process. MS&T 2019, Portland, OR, US.
  11. 6Bandyopadhyay, R.*, Prithivirajan, V., Peralta, A., & Sangid, M. D. (2019). Microstructure sensitive critical plastic strain energy density criterion for fatigue life prediction across various loading regimes. MS&T 2019, Portland, OR, US.
  12. 5Bandyopadhyay, R.*, Prithivirajan, V., & Sangid, M. D. (2019). Uncertainty quantification in the mechanical response of crystal plasticity simulations. MS&T 2019, Portland, OR, US.
  13. 4Bandyopadhyay, R.*, Prithivirajan, V., Peralta, A., Sangid, M. D. (2019). Microstructure sensitive critical plastic strain energy density criterion for fatigue life prediction across various loading regimes. ICME 2019, Indianapolis, IN, US.
  14. 3Bandyopadhyay, R.*, & Sangid, M. D. (2019). Linear friction welding of Ti components: investigation of residual stress and fatigue performance. ICME 2019, Indianapolis, IN, US.
  15. 2Bandyopadhyay, R.*, Sangid, M. D. (2019). Modeling the role of inclusions and debonded region on the fatigue performance of Ni-based superalloys. TMS 2019, San Antonio, TX, US.
  16. 1Bandyopadhyay, R.*, & Sangid, M. D. (2018). Polycrystal plasticity modeling of high cycle fatigue behavior in Ti-6Al-4V. World Congress on Computational Mechanics (WCCM) 2018, New York City, NY, US.

Teaching

At IIT Delhi — Postgraduate Courses
APL787 / AML7270

Fatigue Failure and Design

Spring 2025, Spring 2026  ·  3 Units
APL871

Product Reliability and Maintenance

Spring 2023, Spring 2024  ·  3 Units
AML7010

Computer Aided Engineering Design

Fall 2025  ·  4 Units
At IIT Delhi — Undergraduate Courses
APL203

Dynamics of Mechanical Systems

Fall 2023  ·  4 Units
APL205

Basics of Computer Aided Design

Fall 2024  ·  2 Units
AML1000

Engineering Mechanics

Fall 2026  ·  4 Units
At Purdue University
AAE204

Aeromechanics II

Fall 2019

Join Us

We are actively seeking motivated and hardworking students to collaborate with our team. Opportunities exist at multiple levels.

Graduate Research

Degree programmes

PhD & MS(R) Students

The Applied Mechanics Department at IIT Delhi typically accepts PhD and MS(R) students twice per academic year. If you are interested in our research and wish to join us, please reach out to Ritwik via email with your CV and a brief statement of interest.

MTech Students

MTech students are admitted to the Applied Mechanics Department once annually. If you are an MTech student in our department and would like to work with us, please contact Ritwik via email.

Undergraduate Projects and Internships

Project opportunities

IIT Delhi BTech Students

BTech students from IIT Delhi are welcome to contact Ritwik for BTP or mini-projects.

Students from Other Institutions

BTech students from other institutions are welcome to contact Ritwik with a current CV for summer or winter internship opportunities.

Contact Ritwik Bandyopadhyay ritwik [at] am.iitd.ac.in
Room No. 4B-17, Block IV, Department of Applied Mechanics, IIT Delhi