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Multimodal nondestructive evaluation of internal surfaces of holes in steel structures

Description:

TECHNOLOGY AREA(S): Electronics

OBJECTIVE: The objective of the topic is to develop a multimodal nondestructive testing device, consisting of at least two complementary modalities, to examine flaws in internal surfaces of holes in steel structures.

DESCRIPTION: Nondestructive evaluation (NDE) [1] of internal surfaces of holes or pipes in steel structures for the presence of surface flaws such as stress corrosion pits and cracks is a difficult task, particularly when the internal space is small, the structure is large and rapid inspection with high precision is desired. The difficulty is further exacerbated when initiation of small cracks (~ few microns in size) is to be ascertained in the presence of other surface features such as pits. Given the importance of NDE to multiple industries, an extensive ensemble of analysis techniques leveraging various scientific principles is available [2]. While the list is exhaustive, typical among the NDE methods that have widespread use are dye penetrant inspection, magnetic particle inspection, Eddy current testing, Infrared thermal testing, laser based probes, optical microscopy, radiography, Ultrasonic testing and 3D computed Tomography. Depending on the application one or a combination of methods is applied to examine the sample of interest. Moreover, NDE is an evolving discipline with continuous improvements in the methods, sample preparation, signal analysis and so forth as well as with developing new techniques. NDE of small spaces such as internal holes or pipes in engineering structures is generally a challenging task. The difficulty mostly arises owing to the small space to insert a probe and the consequent impediments to manipulate the probe in the tight space and acquire reliable data at high speed with precision and accuracy. Oftentimes detection of surface flaws such as cracks in such internal surfaces is almost impossible if other imperfections like stress corrosion pits are also present. It is generally true that environmentally assisted cracks are often initiated at corrosion pits and models that are developed to predict lifetime of the parts rely on accurate information on the pit to crack transition and on the statistical distribution of the pits/cracks. Bore evacuator holes in gun tubes such as M284 [3] exemplify a small space that presents a challenge for NDE for the reasons mentioned above. Unambiguous identification of surface flaws in the midst of corrosion pits and the derivation of accurate and reliable statistical parameters of their distribution are an important problem which requires an innovative NDE approach.

PHASE I: A novel multimodal NDE device consisting of at least two complementary modalities will be developed for examination of the internal surfaces of small holes such as the bore evacuators in gun tubes. The modalities considered shall be limited to techniques that rely on electromagnetic testing, microwave/millimeter-wave, ultrasonics and laser testing. Signal processing and fusion of results from the modalities will be an essential feature of the final design. Considerations should be given in the design for a portable and field-usable product at the end of Phase II. The design should be capable of examining holes of nominal diameters 5-7 mm and of either cylindrical or conical geometries in steel structures. It should be able to examine surfaces of different surface finish. It is preferred that this technology easily lends itself for integration with existing bore mapping equipment, such that all barrel inspections can be accomplished through one machine. At the end of Phase I either by prototyping or by modeling the capability of the multimodal method to detect cracks of the order of 10-20 um inside of the holes will be demonstrated. The technology should be scalable to larger holes up to 160mm.

PHASE II: Based on the design from Phase I, a multimodal device for nondestructive examination of the inside surfaces of bore evacuator holes in gun tubes shall be demonstrated at the end of Phase II. The device shall have features such as portability, field-use, field-calibration, easy and rapid inspection (e.g., less than 10 minutes per hole). It shall be capable of detecting cracks of the order of 10-20um or less in the presence of other surface flaws such as corrosion pits inside the holes. It shall be adaptable for examining holes of both cylindrical as well as conical geometries. It shall include advanced signal processing and algorithms to derive reliable statistical information of various surface texture parameters as defined in International Organization for Standardization, ISO 25178 for quantification of areal surface texture.

PHASE III DUAL USE APPLICATIONS: The development of a multimodal NDE device for probing the internal surfaces of small holes in steel structures will have an important military application in the examination of bore evacuator holes in gun tubes for unambiguous identification of surface flaws that may be hidden among corrosion pits. Successful completion of the project will result in the immediate transition of the technology to the examination of gun tubes in depot and/or in the field. As a strategy for transitioning the technology, we will engage with Project Manager Armored Brigade Combat Team (PM ABCT) who serves as the life-cycle manager for Army’s combat vehicle programs including Paladin in which the routine examination of gun tubes will be of importance. In addition, we will approach the logistics and sustainment organization in Anniston Army depot who has the responsibility for field examination of gun tubes. Involving such stakeholders early on in the SBIR will increase the likelihood of transitioning the technology. The technology will also have multiple applications in the commercial sector including detection of fine cracks in nuclear steam generator tube, assessment of the integrity of gas generator injector tubes in the space industry and flaw detection in small bores in aircraft Components.

REFERENCES:

    • Nondestructive testing: http://en.wikipedia.org/wiki/Nondestructive_testing

 

    • The American Society for Nondestructive Testing, Inc. (ASNT), Nondestructive Testing Handbook, 3rd edition, Volume 10, (2012). ISBN: 978-1-57117-187-0.

 

    • http://www.dtic.mil/ndia/2012armaments/Wednesday14093humiston.pdf

 

  • http://en.wikipedia.org/wiki/ISO_25178

KEYWORDS: Nondestructive evaluation, multi-modal methods, bore evacuator holes, gun tubes, surface cracks, stress corrosion pits.

  • TPOC-1: Venkataraman Swaminathan
  • Phone: 973-724-7455
  • Email: venkataraman.swaminathan.civ@mail.mil
  • TPOC-2: Ryan Hooke
  • Phone: 973-724-9227
  • Email: ryan.t.hooke.civ@mail.mil
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