1/22/2016 Emily Scott
The field of nondestructive testing and evaluation is consistently changing. According to ISE professor Henrique M. Reis, this fact doesn’t make it any less important.
Written by Emily Scott
The field of nondestructive testing and evaluation is consistently changing. According to ISE professor Henrique M. Reis, this fact doesn’t make it any less important.
Nondestructive testing and evaluation is the use of physical principles to evaluate materials, components and assembly of components without damaging their serviceability.
“The best way to describe it is when you go to the doctor because you have a cough, he uses a stethoscope, so he uses acoustics to listen to your lungs. We also use acoustics,” Reis said. “If you have kidney stones or there is a need to check on a fetus, they use ultrasonics. We also use ultrasonics.”
Nondestructive testing, Reis explained, also uses many other methods that cannot be used in humans, such as electromagnetics and liquid penetrants. Instead, these methods are used in aircraft industries, infrastructure, i.e., bridges, pavements, etc., and power plants, for example.
“The idea is to be able to inspect and certify quality when you only have one component,” Reis said. “Many people are familiar with statistical quality control. What that means is, you make a thousand parts, test 500 of them, and then hope like hell that the other 500 have the same statistical distribution. In nondestructive testing, we can evaluate a single component for its fitness-for-service.”
The main difference with nondestructive testing, then, is its ability to inspect a single part.
“You cannot break a bridge if you only make one,” Reis illustrated.
Reis said the main goal of nondestructive testing and evaluation is to prevent mistakes to assure that the parts of a structure that are in service do not fail unexpectedly and cause loss of property or life.
“When a doctor makes a mistake, one person dies,” he said. “If a person inspecting aircraft or a bridge makes one mistake, many people die.”
The fundamentals of this field of research are taught in Reis’s class, GE 412 (Principles of Nondestructive Evaluation) and through the Nondestructive Testing and Evaluation (NDT&E) Research Laboratory, which he directs. The lab is located on the fourth floor of the Transportation Building and began with a Senior Design project in the mid 1980s, according to Reis. He said that after completing a project using acoustic emission, a common method of nondestructive testing, he began to conduct more work in this area with borrowed equipment.
After receiving a grant from the National Science Foundation (NSF) in 1989, he was able to buy his own equipment for the lab. Since then, the NDT&E laboratory has been home to countless projects involving concrete, bridges, safety glass, the decay of wood in telephone poles, advanced ceramics, corrosion, engineered wood, and much more.
Compared to other ISE labs, Reis said the NDT&E laboratory is “very different” because it has both computers as well as equipment that is specific only to this field. Graduate students and students enrolled in GE 412 use the lab to learn the techniques that are commonly used in nondestructive testing and evaluation.
“[GE 412] provides the basics to start working in the lab,” Reis said. “After that course students can start working by themselves in the lab.”
Ben Ervin worked in the NDT&E laboratory from 2002-07 as a graduate student and worked on an NSF-funded project monitoring corrosion damage in reinforced concrete structures using guided ultrasonic waves.
“I learned so much in the NDT&E laboratory it's probably impossible to communicate entirely,” Ervin said. “Professor Reis has a state-of-the-art laboratory in terms of nondestructive testing and evaluation equipment (e.g., transducers, signal generators, filters). I learned how to setup and analyze cutting-edge experiments which has proven to be invaluable to my career.”
Jacob Arnold worked in the NDT&E laboratory as a graduate student and conducted research for his thesis, completing his master’s degree in 2014. His focus was on studying sustainable asphalt pavements.
“Besides the wealth of information I acquired about asphalt and [nondestructive] test methods, one of the most valuable things I took away from working in this lab was learning to self-reliantly set up, troubleshoot, and utilize test software and equipment,” Arnold said.
He said this skill has proven to be very useful in his current position as a test engineer at Raths, Raths & Johnson, a structural forensics engineering and architectural firm in Willowbrook, Ill.
“More generally, working in the NDT&E lab taught me how to overcome obstacles and how to appreciate the value of persistence and hard work despite the frustrations that sometimes accompany the pursuit of new knowledge,” Arnold said.
Both Ervin and Arnold said they enjoyed working with Reis because he had a desire to help his students.
“He has a good sense of humor and a rapport with his graduate students,” Ervin said. “Most importantly, he cares about his students and genuinely wants to see them succeed.”
Ervin said he still visits Reis from time to time to discuss his research and update him on his career. He remembers Reis as being “extremely generous with his time” in the lab, making himself available to students.
“[Reis] would always say, ‘You get out of grad school what you put into it,’” Arnold said. “If you are a motivated individual, Professor Reis is a very experienced resource who will guide you towards your goals and help you produce your very best work.”
Reis said that over the years, he has been “very fortunate with many good students.”
One of Reis’s current research projects is analyzing high temperature hydrogen attack, which is a problem that occurs in steel that is operating in high temperatures and high hydrogen partial pressures. The hydrogen in the steel migrates through the steel, combines with carbon, and forms high pressure bubbles of methane inside the steel. These micro-bubbles then grow and coalesce into larger fissures that lead to failure of pressure vessels. Reis said his work is in monitoring these vessels.
Another ongoing research project addresses the preservation of asphalt pavements. In the same way humans use creams on their skin to turn back the clock, certain materials named “rejuvenators” can be periodically sprayed on asphalt pavements to restore the pavement top material layer (i.e. skin) to their original material properties. By properly scheduling the pavement maintenance with rejuvenators, the useful life of the pavement can be considerably increased. Reis said potholes will then be a thing of the past.
He said the field of nondestructive testing and evaluation will only continue to grow and change with time.
“Everyone understands our infrastructure is decaying,” he said. “How do we know when to repair it? We need to test it, or better, to develop methods that are able to continuously monitor its fitness-for-service.”
According to the American Society of Civil Engineers, one in nine bridges in the United States are rated as structurally deficient. Reis pointed out that this is only the tip of the iceberg.
“We only pay attention when a bridge fails, or a plane falls down, or a power plant explodes,” he said. “But there are many other accidents that can be prevented with proper testing and evaluation, or better with continuous condition monitoring.”
VIDEO: NDT&E grad student Megan McGovern describes her research.