In the IoT Age, Structural Health Monitoring Makes the World a Smarter, Safer Place to Live. If your health were constantly monitored 24-7, 365 days a year by a “personal doctor” equipped with artificial intelligence that could catch early warning signs and provide real-time diagnoses, you could skip periodic checkups while preventing major illnesses and living healthier and longer.
This may sound like science fiction, but for manmade structures such as airplanes, trains, bridges, pipelines, and heavy machinery that are critical parts of our infrastructure, this technology is already available. It’s called structural health monitoring (SHM). The most advanced version of this sensor-based “personal doctor” collects data, processes it, and then determines whether the structure needs extra attention where cracks are beginning to form or bolts are becoming loose—it does this automatically and around the clock. This technology will not only prolong the life of structures, but will also help to avert catastrophic structural failures that endanger people’s lives.
“In the digital society, or smart city (where things are operated autonomously and managed efficiently based on big data collected by sensors), you will have to know the safety, reliability, and health of your system,” says Dr. Fu-Kuo Chang, professor of aerospace engineering at Stanford University and a pioneering researcher of SHM. “That means you have to have a built-in doctor in your system that will automatically perform.” Without such a system, Dr. Chang explains, an autonomous car cannot say, “Look, I’m in good shape. I can drive myself!”
SHM Saves Time and Money
In October 2018, Marubeni invested in Acellent Technologies, a Silicon Valley company that designs, develops, and sells SHM systems. The company offers integrated products: sensors, data-acquisition hardware, and intelligent software using diagnostic algorithms. “It’s a complete IoT (Internet of Things) solution,” says Irene Li, president and CEO of the company. “We can monitor critical structures from anywhere, anytime—this is something very important for the future of AI.”
Acellent’s SHM system automatically and constantly monitors the health and manages the life cycle of metal and composite materials, such as carbon fiber reinforced plastic, a material commonly used in automobiles and airplanes. Types of damage it can identify include fatigue cracks, corrosion, delamination, de-bonding and impact damage as well as bolt loosening. It can also predict how much longer the structure will survive given the current loading, operating, and environmental conditions.
Many companies are eagerly exploring applications for this cutting-edge SHM technology, and one such application is in helicopters. Vibrations due to the constantly spinning rotor blade cause fatigue cracks which can occur both in visible areas and in areas that are harder to access. Acellent’s on-board SHM system transmits sensor data to cloud services for storage, allowing operators to monitor the integrity of their helicopters from anywhere in the world.
Just like humans, all structures age over time. They are also subject to mishandling by their human operators, which can cause damage. Under conventional schedule-based maintenance, inspections are planned and periodic. Some operators perform frequent inspections while others need to disassemble their structures to investigate the damage. Yet, the timing can be tricky: too late and serious damage already exists, too early and the operator incurs avoidable costs of performing an unnecessary inspection. It also creates downtime and lost revenue; during these inspections, operators need to stop their services or production lines, which can hurt their businesses.
Acellent’s SHM system enables condition-based, predictive maintenance because it provides operators with automated, real-time warnings. “Our customers can prepare in advance of structural failures,” Li says. This can eliminate unnecessary inspections and minimize human labor, leading to massive cost savings.
Making the Impossible Possible
The backbone of Acellent’s SHM technology is the SMART Layer®, a very thin film with an array of networked piezoelectric sensors that can actively inspect a structure by sending out ultrasonic wave pulses—a unique feature called interrogation, which most other sensors do not have. It can be applied to any type of structure, large or small, simple or complex. Unlike individual sensors that monitor individual points, the SMART Layer’s networked sensors cover the entire area, leaving no blind spots.
While the technology is complex, the concept of the system itself is simple. Once installed on a structure, the SMART Layer’s networked sensors send out ultrasonic wave pulses and collect data. Specialized portable hardware acquires data and runs a quick ultrasonic scan of the structure (periodically, on-demand, or in real time). Intelligent software then analyzes the data, which shows how the waves propagate through the structure. Based on this analysis, an operator of the structure can identify the location, size, and type of damage occurring in the structure.
This combination—damage detection plus quantification—is Acellent’s competitive edge. Other existing SHM systems can also detect changes in the integrity of the structure, but they are limited to monitoring temperature or vibration. Acellent’s technology prevents structural failure by identifying damage, classifying the damage type, calculating the damage size and location, and even estimating the remaining useful lifespan of structures. Making structures “smart” enough to monitor their own health and autonomously flag changes in their own condition once sounded impossible—Acellent has made the impossible possible.
One key enabler is Smart Layer’s networked sensors; another is a highly sophisticated algorithm that uses mathematical formulas, statistics models and physics-based simulations. “We have invested a lot of time and effort focusing on the development of this algorithm.” Li says. “This is something that we are very proud of.”
Innovative Technologies Must See the Light of Day
The Smart Layer technology was originally invented in Dr. Chang’s laboratory at Stanford University and its patent has been licensed exclusively to Acellent since the company was founded in 1999. Based on the Smart Layer technology, the company built integrated SHM systems and currently boasts 37 patented technologies of its own.
“We decided to bring the technology outside to have a company to really focus on technology maturation with the support of industries,” Dr. Chang explains the reason he co-founded the company. He emphasizes the importance of bridging the so-called technological “valley of death,” a gap between academic research and commercialization where inventions are stranded in university laboratories and never utilized in the real world. “As an engineering professor, I would like to see that the technology we have developed is used to make an impact on society,” he says. “And what I would like to see is that the impact is as broad as possible.”
In the beginning, the company’s core business revolved around the US government funds that came from Defense, Homeland Security, Energy, and Transportation. For example, the company was asked by the Department of Homeland Security to develop health-monitoring systems that could examine the structural health of architecture. The tragedy of 9/11 raised the need for more advanced systems to ensure the safety of firefighters who would enter buildings in the aftermath of a natural disaster or explosion.
Since its early days, Acellent has also continued to work very closely with the aerospace industry where the most rigorous testing is required. “It has set the bar high for technology inclusion in its platforms,” says Amrita Kumar, executive vice president, who joined the company in the same year as its inception. She added that long-term collaborations with leading companies such as Boeing and Airbus have allowed the company to mature its products to meet their requirements.
Once your innovation becomes the gold standard of the industry with the most stringent standards, you attract notice and attention. This is exactly what happened to Acellent. The company was then able to explore different avenues where its technology can be applied. Today, it has a diverse customer base including railway, automobile, heavy machinery, energy, and civil engineering companies. “We are the company that is transforming the concept and dream of SHM into reality,” Kumar says.
The Whole Marubeni Platform Working As One
“I think that the phase they are now in is having the technology ready for broader commercialization,” says Bill Campbell, an early Acellent investor, who observed the evolution of the company. “Marubeni will bring resources to bear for completing the final stretch to broader commercialization.” He points out that marketing technologies for a wide spread of applications is always a challenging point for tech companies. “The partnership with Marubeni certainly positions Acellent well to meet that challenge.”
For Marubeni, investing in a technology spin-off company from a university is a new business model, but in this collaborative journey with Acellent, the company can fully demonstrate its strengths cultivated through decades of experience in building an extensive business network.
“We are a global company that has a worldwide network of customers and subsidiaries, so we will be able to make business models and find customers for Acellent,” says Dongil Park, who leads an internal taskforce of Marubeni to explore business opportunities using Acellent’s SHM solutions. “Maximizing such diversified assets as ours, we can perform proofs of concept in our own pilot projects to bring Acellent’s technology to fruition where it can really make an impact on society in so many different areas.”
Park, who works in the Industrial System & Renewable Energy Solution Department, “rediscovered Marubeni” by learning about what other departments do. “We have outstanding groups of highly knowledgeable professionals that are experts in their fields,” Park says. Their expertise, however, often remains unshared or undiscovered because of a lack of opportunities for horizontal collaboration across different divisions. Park believes that working together with Acellent will generate new synergies among divisions and strengthen the togetherness of the whole Marubeni platform.
Acellent is a small tech company of about 30 engineers, but it is committed to becoming a global leader of the SHM solution market. The company is now hopeful that the partnership with Marubeni will get them on a fast track. “There will be tremendous value in working with Marubeni,” Li says. “They can help us grow and enhance our vision to deploy our IoT solutions to all structure, all markets.”
All information contained in this article is based on interviews conducted in December 2018.
