Imagination. Visualization. Persistence. These three things are what it takes to be an inventor, according to Charles “Chuck” Popenoe who was inducted into the A. James Clark School of Engineering’s Innovation Hall of Fame yesterday.

“As a student here, I was determined to make it as an engineer, because that’s all I ever wanted to be in my life,” he said. “I really enjoyed my time at the University of Maryland; it’s been my second home.”

Popenoe, who graduated from the University of Maryland in 1957 with a bachelor’s degree in aerospace engineering, was recognized for inventing SmartBolts®, which remains the only technology of its kind—even after more than 50 years. SmartBolts fasteners display actual tension with a built-in indicator that changes color as the bolt is tightened or loosened. The indicator design is reusable so it provides value at installation and allows you to monitor fastener preload (the force applied as a result of installation) for the life of the bolt.

“Today we honor the importance of innovation not only at the Clark School, but throughout the University of Maryland,” said Darryll Pines, Clark School dean and Farvardin Professor of Engineering.

Before presenting Popenoe with a medallion for his achievement, Mary Ann Rankin, University of Maryland senior vice president and provost, said: “Today, we honor Mr. Charles Popenoe, who is part of a legacy of past, present, and future innovators. I am so proud to stand among such notable innovators in this hall.”

After he graduated, Mr. Popenoe worked on missile and rocket design for the U.S. Navy. In 1962, he began a 27-year career at the National Institute of Standards and Technology (NIST) as an experimental plasma physicist. In this capacity, he invented and developed a universal laboratory data acquisition and control system called MIDAS, which continues to be used throughout NIST and in many world laboratories. Popenoe also designed and constructed the Facility for Spectroradiometric Calibrations (FASCAL), which has been in operation since the 1970s for the calibration of laboratory spectral radiance sources.

Following his retirement from NIST, Mr. Popenoe founded Stress Indicators, Inc. (now known as Industrial Indicators) to sell his SmartBolts. He developed and marketed a manufacturable model called the DTI SmartBolt which was adopted by General Electric (GE) for use in its electrical distribution product line. GE’s ongoing use led to commercial success of the product and growth of the company. The DTI SmartBolt displays actual fastener tension with a red to black scale. If the bolt is loose, the indicator is red; and when the bolt has proper preload, it is black. Today, hundreds of thousands of DTI SmartBolts are being used by many of the world’s leading companies.

Mr. Popenoe has been granted some 35 U.S. and international patents. His awards include: two Gold Medal Awards from the Inventors Exposition in 1971; the U.S. Department of Commerce Silver Medal Award for Laboratory Automation from NIST in 1975; the Award for Exceptional Creativity from Intellectual Property Owners in 1994; First Place from the U.S. Patent and Trademark Office Inventors Exposition in 1994; and the Lifetime Achievement Award from the Western/Ellington Alumni Association in 2000.

The event brought together former Innovation Hall of Fame inductees, friends, family members, faculty, staff, and students, as well as students from College Park Academy, a charter school middle and high school located in Riverdale Park, Maryland.

The Innovation Hall of Fame recognizes Clark School alumni, faculty, and associates who have pioneered many of the most significant engineering advances in the past century. Inductees include Robert Briskman, the co-founder of Sirius Satellite Radio; George Laurer, inventor of the Universal Product Code; and Brian Hinman, the innovator behind the Polycom SoundStation conference call device. For more information, visit

December 7, 2018

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