Ultrasonic Characterization of Explosively-Bonded Concentric Tubes

5/24/2010 NDIA Conference 1

Materials Evaluation and Testing Laboratory (METLab)Mechanical Engineering Department, Box 2219 SCEH 214 South Dakota State University, Brookings, SD 57007-0294

Phone: (605) 688-4300, Fax: (605) 688-5878, http://www.sd-metlab.org

Presented by: Chris JerredAcknowledgements: Dr. Fred Delfanian, Dr.

Jikai Du, & Dr. Tao Huang

5/24/2010 NDIA Conf. 2

Presentation Outline

• Background• Purpose• Machining• Microscopy• Ultrasound techniques• Conclusions• Future work

Background

• Concentric tubes used in military applications• Wear resistance liner (donor tube)• Tubes bonded explosively• Many factors in process, affect bond quality• Ends of composite tube are scrapped• Bond quality difficult to ascertain

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Aim

• Find inspection method for material interface• Non-Destructive Test (NDT) is preferred• Assess overall bond quality• Serve as QC or life monitoring tool• Correlate NDT and destructive methods

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EB Specimen

• Steel major tube• Alloy donor tube• ~ 3” length• ~ 4” OD, 1” ID

• 1 “poor” - PEBS• 1 “good” - GEBS

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Machining

• EDM samples– Destructive tests– Microscopy– Hardness tests– Alloy analysis

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Microscopy

• SEM– Destructive, time consuming, small sampling area– Looking for “wavy interface” and “material mixing”

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GEBS PEBS

Microscopy

• Digital Microscope– Quick, little preparation, color

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GEBS PEBS

Ultrasonic Methods

• Physical Acoustics– Immersion Scanner

• Resolution 0.0001”• Max 20 in/sec• 2,000 lbs max load• 3-10” diameter tubes• Up to 5’ length

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Bond Focusing10

OD

Liner

ID

Recessed areaReflection from recessed area

Frequency Optimization

• High frequency– Inc. resolution– Same settings

• 20 MHz selected– On hand

• Gap = Removed• Slant = Tuning

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10 MHz

20 MHz

Gradient

• Caused by ?– Δ bond– Scan method

• Reversed part– Same scan– Same trend

• Δ bond is cause• Less obvious GEBS

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Stripes

• Caused by ?– Wavy axial bond– Scan method

• Changed step size– Same results

• Scan method

5/24/2010 NDIA Conf. 135 m

m50 m

m

0.5 deg0.05 mm

0.5 deg0.5 mm

Good vs. Poor

• GEBS– Lower reflection amp.

• PEBS– Higher reflection amp.

• Good bond provides easier transmission of acoustic energy

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Conclusions

• Semi-Quantitative– Need reference tube as standard

• Poor vs. Good Distinguishable• Observed Gradient Due to bond• Frequency Effects Higher (20MHz) is Better• Stripes Due to scan method

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Future Work

• Reference specimen

• Hardness vs. alloy composition– Micro hardness tester– Alloy analyzer

• Correlate to NDT-UT & destructive results

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Questions?

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• Chris Jerred• Materials Evaluation and Testing Laboratory (METLab)• Mechanical Engineering Department, Box 2219 SCEH 214 • South Dakota State University, Brookings, SD 57007-0294• Phone: (605) 688-4300, Fax: (605) 688-5878,

http://www.sd-metlab.org