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College of Engineering and Computing

  • Yu, Giurgiutiu and Banerjee stand next to each other.

The pioneers of structural health monitoring

How one research group in SC is working to make the lives of millions safer

By Abe Danaher | July 20, 2020

“Where is this group going? What is the horizon? What challenges are ahead of us?”

Victor Giurgiutiu’s words hover in the air between him and his colleagues, Lucy Yu and Sourav Banerjee. All three know the importance of their answers as America’s infrastructure crumbles around them.

“Some structures can crumble, and you just complain about them,” Giurgiutiu says. “Others crumble and people die. So that’s where I am concerned.”

Using structural health monitoring technology, the three teammates work like doctors, evaluating the ‘health’ of America’s safety-critical structures by looking at their well-being beneath the surface. Whether roads, bridges, nuclear reactors, planes or spacecraft, their goal is simple: to make these structures safer by detecting weaknesses and ‘illnesses’ long before cracks appear, or even worse, lives are lost.

“We are working on a very interesting topic for everyone in this world – how to prevent accidents,” Giurgiutiu says. “I mean, we cannot interfere with God’s mission, but we can do things about our man-made structures to make the world a safer place.”

The beginning

In the early 1990s, Victor Giurgiutiu’s research curiosity got the best of him. He heard of a new concept that was emerging called "smart structures,” a concept that sought to make non-living structures capable of "feeling," “responding” to and “reacting” to stimuli in their environment.

 “I found that collegiality between us and the openness and the transparency and also the friendly environment allowed us to grow with new ideas.”

- Professor Sourav Banerjee

To many at the time, the idea was laughable; something that only the craziest academics could cook up. But, for Giurgiutiu, it sounded like a challenge. He joined the small smart structures community with an open mind and aspirations to change the world.

“We were dreamers. We were really dreamers,” he says.

By 1997, the group had grown, and the smart structures and materials community had its first conference. But, its growth in the academic world meant nothing yet to the manufacturing industry. Designers of trains, airplanes, space shuttles and tanks were implementing safety factors into structures’ designs to compensate for unknowns. These designers didn’t know who would be operating the structure, what environment it would be used in, or what conditions it would face, so they did their best to prepare for anything. While making these structures safer, this process also resulted in heavier structures.

Giurgiutiu sought to change that by adopting a Bayesian approach that would allow for the forecasting of structures’ useful lives to be constantly updated using the information collected by a structural health monitoring system. By 2003, he had received the Structural Health Monitoring Person of the Year Award and had begun developing ultrasonic methods using piezoelectric wafer active sensors (PWAS) to allow for real-time monitoring of safety-critical structures. He didn’t want to leave anything to the unknown.

Instead of waiting for a crack to appear in a plane’s wing, or guessing when a bridge would collapse, he wanted to know that something was wrong before it was too late. Like regular check-ups at the doctor, he wanted to detect and address an oncoming ‘illness’ before it appeared.

“I cannot look at all the aspects that generate an accident, but I can focus on what I know – the structure,” he says. “And I’m trying to understand how we address the structure’s safety issues.”

With that simple idea, he changed the field of structural health monitoring and positioned the University of South Carolina as a leader in the field. Then, he expanded his team, and in the process, changed the trajectory of two young researchers: Lucy Yu and Sourav Banerjee.

“He has good vision about the field: where we should go, what are the needs,” Yu says. “So, he did provide great guidance not just for me and Sourav, but other program managers and for people in our field as well.”

Mentor to mentee

Lucy Yu entered the structural health monitoring field in the back room of Giurgiutiu’s lab, wiring and soldering antennae to her doctoral advisor’s cutting-edge PWAS system.

Doing the work with her hands made her wonder: was she doing the installation carefully enough? What would happen if she missed a soldering? Was there a way to reduce human involvement in the process? Sitting there in Giurgiutiu’s lab, wire chafing at the edge of her pointer fingers, Yu decided she was going to find a solution to her questions and one day, create a way that sensing could be done without putting a sensor on the structure, so that no one would ever have to do that work again.

“I’m not complaining. That was a great motivation for me,” she says now with a laugh. “I mean, it pushed me to look for the solution and finally develop the noncontact and remote sensing methods.”

Building upon what she learned from Giurgiutiu, Yu sought to push the entire field of structural health monitoring forward after completing her doctorate in 2006. As a professor at the University of South Carolina College of Engineering and Computing, she began developing a model that would allow ultrasonic equipment to be used without touching the structure it was evaluating.

Adhesives, liquid couplants, wiring and soldering would be things of the past, as would the extra variables each of these brought into the research. She settled on laser-based technology and began testing it to see just how promising the remote evaluation method was. As she took steps toward transforming the field her advisor had built, she was reminded again of his pioneering work, as his PWAS model became the gateway to proving that her new technology worked.

“What did Newton say?” she asks. “You have to stand on other people’s shoulders to reach higher? I can’t do this by myself. So, when I did the step-by-step evaluation for the new noncontact methods, I made a comparison with the well-established PWAS system to have confidence that it could work.”

Her remote and contactless evaluation method transformed how structural health monitoring technology could be used. And, in doing so, it caught the energy industry’s attention as they sought to make nuclear energy even safer. Just this past year, the Department of Energy awarded her a three-year, $800,000 grant to evaluate the integrity of nuclear reactor advanced tolerance fuel cladding materials. On top of that, they gave her another $800,000 grant this year to detect and mitigate cracks in the internal canister of dry nuclear storage facilities.

And just like that, a new pioneer in structural health monitoring was born.

From aerospace and energy to biology and agriculture

Sourav Banerjee’s story bares many similarities to Yu’s. He did his doctoral work at the University of Arizona under Tribikram Kundu, who happened to be very close friends with Giurgiutiu. When Banerjee came to South Carolina in 2012, his goal was to push what Giurgiutiu had pioneered down a new path, and in the process, complement the work of the man who helped make this entire field possible. 

“When I came, I talked with Victor and said, ‘you are already doing structural health monitoring, and I have been doing that work as well, do you mind if I work in the same area, and also go and explore some more within it?’ And he was very open to that,” he says. “I found that collegiality between us and the openness and the transparency and also the friendly environment allowed us to grow with new ideas.”

Soon after arriving, Banerjee found his place in Giurgiutiu and Yu’s team. 

“Professor Giurgiutiu says we are going to prevent the accident,” he says. “And if you trace back from an accident event, just before the accident, there’s going to be a significant size of the damage forming that Lucy is going to detect, saying the material is already damaged. My area, my work, comes a little bit earlier saying that the material is prone to develop damage.”

In Yu and Giurgiutiu, Banerjee found the perfect colleagues. And, among the three of them, the field of structural health monitoring found its leaders – both past and present – united in one team, one university, and one state.

“In the U.S., structural health monitoring means the University of South Carolina. Structural health monitoring means Stanford University. And also, structural health monitoring means Purdue University,” Banerjee says. “If you see our student profile, we pull very good students. Top masters students from top universities across the world come to South Carolina because we have such a well-recognized group.”

While Yu worked to break the barriers of how ultrasonic evaluation could be conducted, Banerjee worked to break the barriers of what it could evaluate. Specifically, he thought the technology could be used to evaluate not just the beam of a bridge, but also the microfibers or micro-constituents making up the material that the bridge’s beam was built from. 

He started using transducers to bring the frequency range of the ultrasound technology from the traditional range of 20-700 kHz up to 1-400 MHz. By doing so, he aimed to evaluate structures at the microscopic level. He began providing Yu and Giurgiutiu early indicators on where to look for weaknesses in the structure – identifying, for example, weak material fibers that were prone to cause future problems.

He also began exploring a new use for the technology, and through grants with the USDA and South Carolina Agriculture Center for Research and Entrepreneurship, brought structural health technology to the fields of biology and agriculture. Its impact in the future, he says, could be great.

“When you ask how a person’s life can be impacted by this technology, it’s first of all medicine discovery,” he says. “Then, in agriculture, we can save a lot of food waste if you know how it can prevent the fungal infections. We can even apply this to bacterial infections and provide effective antibiotics in some environments.”

These thoughts and his work on them earned Banerjee the 2019 Structural Health Monitoring Person of the Year Award. Now, he is working to develop ultrasonic microfluidics that could help with early detection of cancer, identify antibodies for the lethal viruses like SARS-Cov-2, and enable the evaluation of new medicines. He is also working on developing artificial cochlea and acoustic devices that can help autistic kids listen to selected frequencies and can create the opportunity for seamless human-robot audible interaction during rescue missions.

A world-leading team

With each passing day, Giurgiutiu, Banerjee and Yu’s work becomes even more important.

On February 5, 2019, President Donald Trump issued a memo titled ‘Rebuild America,’ detailing the state of America’s infrastructure. It specified that more than 50,000 U.S. bridges are rated as “structurally deficient.” One out of every five miles of highway pavement in the U.S. is in “poor condition.”

It’s because of this aging infrastructure, Giurgiutiu says, that the team’s work is increasingly valuable to the everyday person.

“Everything is crumbling,” he says. “We have such a lack of concern about repairs, and I don’t understand why this attitude exists.”

Giurgiutiu, Yu and Banerjee believe that structural health monitoring poses a viable solution to addressing America’s crumbling infrastructure. They believe that the technology could provide direction on what infrastructure to fix first, and in the future, can ensure that new, expensive infrastructure projects are sound investments that maintain their health for years to come.

Already, many of the world’s largest corporations, including Airbus and Delta, are beginning to implement the technology into their manufacturing processes. The dream that Giurgiutiu started many years ago is beginning to become a reality. However, he says, there is still very far left to go.

“Somewhere there is a pot of gold, so to say, that we can reach with safety and knowledge,” Giurgiutiu says. And if history is any indicator, the end of that rainbow is exactly where it started – at the University of South Carolina.

Challenge the conventional. Create the exceptional. No Limits.