SBIR 95-1 SOLICITATION
AN ELECTROMAGNETIC "SMART WASHER" FOR DETECTING BOLT-HOLE CRACKING
Bolt-hole cracking is a common problem to both new and older aluminum aircraft. Traditional
manual ultrasonic and eddy current inspections are costly and slow, and cannot inspect key
structures (such as wing spars) without disassembling the plane. In the latter case, the cost of
disassembling the plane far exceeds the cost of inspection, and also risks inducing new damage
during the disassembly/re-assembly process.
Innovative Dynamics proposes to address this problem by developing a "smart washer" for
electromagnetically detecting bolt-hole cracking. We will build the eddy current coil and ferrite
materials into a high-strength washer, then use eddy current techniques to detect the onset &
progress of bolt-hole cracks. The sensor electronics would then be wired into the plane's
avionics, or brought out to an inspection port.
IDI will demonstrate this technology by designing washers containing eddy-current sensors. We
will test these "smart washers" by mechanically inducing bolt-hole cracks in aluminum specimens
containing the bolt-"smart washer"-nut combination. The "before & after" sensor readings will be
validated with measurements taken with a hand-held eddy current probe, as well as visual bolt-
hole inspection. Finally, we will then develop a fuzzy-logic classification scheme for detecting the
onset & severity of bolt-hole cracking.
Potential Commercial Applications:
Commercial and military aircraft manufacturers worldwide could incorporate such a system into
their new and upgraded designs. In addition, it would have a ready market among owners of GA
(General Aviation) aircraft that are susceptible to bolt-hole cracking in wing spars.
This same technology could be applied to any application involving a critical, hard-to-access bolt
holes - such as those found in cranes, heavy machinery, bridges, and the nuclear industry.
Name and Address of Offeror:
Innovative Dynamics, Inc.
244 Langmuir Lab
95 Brown Road
Ithaca, NY 14850-1252
Small Business Innovation Research Program (SBIR) &
Small Business Technology Transfer Program (STTR) Programs
Electronic Management System (EMS)
National Aeronautics and Space Administration (NASA)
The SBIR/STTR EMS site is maintained by Steve
Hu, Hughes STX.
For comments and questions, contact
Updated: Feb. 7, 1996