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Caroline Heitmann: Building With Intention

Challenge: Restoring and Improving Urban Infrastructure

Major: Civil Engineering (Structural Concentration), Certificate in Architectural Engineering

Advisor: Henri Gavin

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Caroline Heitmann using surveying equipmentWhat are your ambitions as an engineer?

I want to work as a structural engineer, contributing to sustainability and our built environment in a meaningful way. I want to focus on being as innovative as possible, and not being anchored by the traditional practices of the past.

One thing I'm interested in is climate change. Disasters are getting worse–how do we design our buildings to be strong enough to stand up to these ever-increasing thresholds? Being able to design and provide shelter for people while they're in terrible circumstances is incredibly important, and a big responsibility.

What made you apply to become an NAE Grand Challenge scholar?

I really liked the idea of having like a grand challenge that a community of engineers is working towards, and the fact that you could make the challenge your own.

I’m someone who likes to plan and stay organized, so having a unifying idea to guide all my activities at Duke was very appealing. At the same time, the parameters of the program are very flexible, so I didn't feel like hemmed in to one particular area of exploration and study.

Tell us about your thesis project, “Stability & Dynamics of Tensegrity.”

Tensegrity is a structural form; in simple terms, it’s a structure made of bars that are always in compression and cords that are always in tension. It’s typically seen as an art form, but it’s increasingly being used for other applications because it’s low cost and efficient.

I really wanted to take the idea of tensegrity a step further, with some sort of resilient, sustainable design. I was thinking about the intersection among infrastructure, which is my grand challenge, and structural engineering, and energy—how might we use a structural form like tensegrity to improve energy resilience?

We came up with the idea of using a solar panel built on a tensegrity model. There are many tensegrity shapes, and I played around with different shapes for the foundation, but we settled on a basic Snelson prism.

The model is very adaptable. Because it can change form easily, it can track the sun throughout the day, maximizing its solar irradiance intake.

It's a simple-looking design, but it's really exciting to see it come to fruition, because I had so many questions in the beginning: How is this going to happen? Where is the sun during the day and how will we calculate what angle the panel should be at, to remain perpendicular to the sun? But it did come together! I did a lot of background research last semester, and we did the bulk of the computational modeling in Matlab this semester. Then I built the small model of the design that you see here.

Overall, we found that a tensegrity-based solar panel support system is 36% more effective than a south-facing, horizontal panel, 21% more effective than than a horizomtal panel inclined at 34 degrees (assuming the solar panel is located at Duke Chapel), and 15% more effective than a panel rotating about its polar axis.

Did the pandemic year affect your work?

It did affect what I had planned for my global experience. I was supposed to working in a lab in Nuremberg, Germany, last summer, researching smart cities and human-centered design, and trying to understand how the indoor landscape affects human health through a program called DAAD Rise. I was hopeful that I could do the work remotely, but it didn’t pan out.

My global experience is therefore projected—I’m beginning a master’s degree in civil engineering at École polytechnique fédérale de Lausanne, in Switzerland, in September 2021. I plan to focus on structural engineering to continue exploring how structures can be strengthened against worsening stressors.

Would you recommend the program to new engineering students? If so, why?

I would definitely recommend it. I feel like the program shaped my Duke career in a positive way, in the sense that it complemented my classes and reminded me to think outside of the bare-bones, grade-oriented, academic landscape. It made me think deeply about what I wanted to do and how I wanted to apply engineering in the future.

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