Events Archive

Modeling Mechanical Instabilities in Epitaxial Barium Titanate Thin Films

Ferroelectric BaTiO₃ (BTO) thin films are promising for electronic and photonic applications. Using Hybrid Molecular Beam Epitaxy (Hybrid MBE), high-quality epitaxial BTO films can be grown with unit-cell-level thickness control. Their behavior, however, is strongly influenced by epitaxial strain and mechanical boundary conditions arising from integration with dissimilar substrates.

In this seminar, I will present continuum theories developed to understand two distinct mechanical instabilities in epitaxial BTO thin films. In the first system, BTO films grown on a sacrificial SrO layer spontaneously roll upon release. A model incorporating polarization effects predicts the characteristic rolled-film diameter as a function of thickness and shows good agreement with experimental observations. In the second system, BTO films grown on CaSnO₃/SiO₂ substrates develop wrinkling patterns. Modeling the film as an orthotropic hyperelastic medium yields analytical predictions for wrinkle orientation and slope that are consistent with experimental measurements. Together, these results demonstrate how energy-minimization principles can be used to explain and predict some rolling and wrinkling instabilities in ferroelectric thin films, providing a framework for the design and control of ferroelectric heterostructures.
 

AEM Welcome Seminar: Fluid Mechanics

Join us for AIAA's 13th annual Aerofair, a student-run career fair centered around aerospace companies. You'll have the chance to network with industry professionals and recruiters.

List of attendees:

• Safran
• ASTER Labs, Inc.
• Sandia National Laboratories
• 3M Company
• Collins Aerospace
• Northrop Grumman
• Aerospace Fabrication & Materials
• AEM Graduate Department

Students are invited to an exclusive, day-long conference hosted by Honeywell Aerospace.

Join us for a unique opportunity to connect with industry visionaries, showcase your academic work, and discover how Honeywell Aerospace is pioneering the future of aviation and technology — and how you can lead the next wave of innovation. Get ready to Build the Future of Flight!

What you can expect

• Executive insights and learning: Gain firsthand knowledge from Honeywell Aerospace leaders on topics such as human factors, systems engineering, navigation, AI, and theoretical physics.
• Career exploration: Network with Honeywell Aerospace recruiters and hiring managers to explore upcoming internship and full-time career opportunities.
• Mentorship and connection: Build meaningful relationships with professionals and peers who are shaping the future of the field.

Find more information and RSVP here.

Bridging Scales in Mechanics: Integrating Data-Rich Experiments with Symmetry-Aware Scientific Machine Learning 

The hierarchical and heterogeneous nature of materials drives their complex deformation and failure mechanisms across multiple length and time scales. Understanding how the microstructural features of polycrystalline metals (e.g.  grain orientations, texture evolution, defect interactions) govern their macroscopic mechanical response remains a key challenge in mechanics.

Recent advances in experimental techniques, such as those in scanning electron microscopy (SEM) and in-situ characterization, now generate massive, high-resolution datasets that capture deformation processes as they unfold. However, extracting meaningful physics from these unprecedented volumes of multi-modal data requires more than traditional analysis. Conventional machine learning approaches often fail to capture the underlying physics and scale-bridging relationships that are essential for reliable predictive modeling. 

This talk explores how scientific machine learning can bridge these scales when built on trustworthy foundations. We will discuss why enforcing known physical constraints, particularly material symmetries ranging from crystallographic symmetries at the grain level to texture-induced anisotropy at larger scales, is essential for creating trustworthy models for scientific discovery. By embedding these intrinsic symmetries, models become more interpretable, data-efficient, and physically consistent, directly addressing critical limitations of black-box approaches. 

Through examples of scanning electron microscopy-based datasets, this talk will demonstrate how integrating rich experimental data with physics-informed architectures can enable trustworthy, interpretable models that respect the fundamental principles governing material behavior and reveal new insights into multi-scale deformation mechanisms.  

Applications for Shape Memory Materials in Wearable Soft Robotics

In this talk, I will discuss applications for shape memory materials in wearable soft robotics featuring ongoing work in the UMN Wearable Technology Lab (WTL). I will specifically cover shape memory alloy (SMA) actuator development, garment integration, and systems design to enable mechanically dynamic garments: garments that can constrict, stiffen, topographically deform, or otherwise physically transform to provide benefit to the wearer. These wearable robotic systems have applications in aerospace systems, medical devices, accessibility solutions, and everyday clothing.

Professor Brad Holschuh is a Distinguished Professor of UX Design, Co-Director of the UMN Wearable Technology Laboratory, and Director of Graduate Studies of both the Design Graduate Program and the Human Factors and Ergonomics Program, College of Design, University of Minnesota.

AEM Welcome Seminar: Aerospace Systems

Mechanics of Growth and Growth of Mechanics

As an active research area in biomechanics, mechanics of growth studies the mechanical aspects of growth of biological tissues. While the classical theories of mechanics have provided powerful tools in studying the growth of biological tissues, the physiological process of growth, in turn, presents special challenges to the theory of mechanics, and brings forth the growth of mechanics itself. In this talk we discuss some issues that have emerged in this process. 

The existing mechanics theory of growth is based on the decomposition of the deformation gradient tensor into a growth tensor and an accommodation elastic tensor. This decomposition requires a fixed reference configuration from which the deformation gradient can be properly defined. It is built on a fundamental premise in continuum mechanics that there exists a one-to-one correspondence between the material particles in the reference configuration and in the current configuration. The assumption of the one-to-one correspondence is, however, inconsistent with a physical process of growth in which the newly deposited materials particles did not exist in a fixed reference configuration. In particular, the existing growth theory is incapable of modeling the surface growth in which changes in topology can occur as a material surface grows into a volume. In this talk, we present a theory that does not require the existence of a fixed reference configuration. 

To set the stage for the new growth theory, we first discuss a theory of elasticity that does not require a fixed reference configuration. In this theory, the movements of the material particles are described by the velocity field in the current configuration. The constitutive theory does not rely on the concept of a natural state and a fixed reference configuration. Instead, it uses the current configuration as reference. As the elastic body deforms, the response function, which gives the stress tensor in terms of the deformation gradient, is constantly updated. We derive an evolution equation for the response function. 

The proposed growth theory is then developed by incorporating a growth rate field into the above elasticity theory. The growth rate field, defined on the current configuration, describes how new material particles are added to a growing elastic body in its current state. For volumetric growth, the growth rate field has its support on the growing region. In contrast, for surface growth, the growth rate field has support on a surface and is conveniently described by singular distribution functions. The velocity field may suffer jump discontinuities across the surface. The evolution equation for the response function of a growing elastic body is derived that describes how the stress changes with growth and deformation. An example of internal surface growth is presented.

Yi-chao Chen is a Professor at University of Houston. He received his Ph.D. from the University of Minnesota, and M.S. from Johns Hopkins University. His research interests include continuum mechanics, biomechanics, stability analysis, bifurcation theory, and multifunctional materials.

Changing the Game in Space Logistics and In-Space Servicing

The Brooke Owens Fellowship goal is to provide opportunities and access to talented female and gender minority students from all backgrounds who have been previously underrepresented in the aerospace industry.

The seminar will help students learn more about the Brooke Owens Fellowship and teach them the best way to apply.