Nondestructive Inspection (NDI) of Fastener Holes in Thick Multi-Layer Structure

Innovative Materials Technologies, Inc. (IMTT) is proposing a Flat Geometry Remote Field & Super Sensitive Eddy Current (FG RFEC & SSEC) technique for the inspection of fastener holes in thick multi-layer structures. Inspection of fastener holes in thick multi-layer structures described in the Topic AF04-134, is a big challenge to all existing or emerging nondestructive inspection (NDI) techniques, including ultrasonic techniques, X-ray, conventional eddy current techniques, super-conductive quanta interface device, etc. Among all ECT’s, the FG RFEC & SSEC is the only technique that has a penetration depth not limited by Skin-Depth, because the signal received by its receiving unit has penetrated through the object wall twice and carries a clean signal about the wall conditions. Therefore, FG RFEC & SSEC is the most promising technique in reaching the goal set in this project topic description. There are three Phase II objectives: Objective # 1: Detection of cracks on F-15 titanium (Ti) spar structures. Objective # 2: Detection of cracks through aircraft bushings. Objective # 3: Inspection of Titanium Structure through Composite Skin. Coupons and specifications of the above three objectives have been specified by US Air Force Research Laboratory. IMTT will develop and deliver a production prototype system based on the remote field eddy-current technology which is capable of addressing multi-layer crack detection in the three areas listed above – F-15 Ti spar structures, aircraft bushings, and Ti structures through a composite skin. The system will also be producible, supportable, affordable and transitionable. One commercial system and three commercial probes with advanced and automated functions will be designed, prototyped, and produced with an appropriate industrial partner, such as SAIC and/or Rohmann. Mr. Sun, Yushi, President of IMTT and Principal Investigator, has more than 19 years of experience in R&D of the FG RFEC & SSEC technique, as well as in finite element modeling of electromagnetic NDI phenomena. He is an active and Founding Member of the International Computation Electromagnetics Society, COMPUMAG, and was a Session Chair and a member of the Editorial Board for a number of international conferences in computational electromagnetics and electromagnetic NDI.