Ultrasonic Measurement of Bending of Bolts

Work performed at Johnson Space Center has brought about a major improvement in the means for measuring the bending that occurs whenever stress is applied to a bolted joint. This major improvement is a measurement method based on ultrasonics. The strain gauges used heretofore in the space program in efforts to measure bending loads or deformations in bolted joints have proven inadequate, in that it has been difficult to perform accurate measurements by use of them. The art of ultrasonics offers an alternative and superior means of performing such measurements; as such, it can be expected to contribute to cost savings and increased safety, not only in the space program but also in military and commercial applications — wherever there are stressed bolted joints that could pose bending hazards. The ability to measure stresses in joints accurately can be expected to contribute to understanding the mechanisms that produce stress failures in critical joints and thereby contribute to the success of efforts to design safeguards that will lower risks to both vehicles and personnel.