development of an acoustic emission test platform with a biaxial stress loading system

S. Mandayam/ECE Dept./Rowan University

Development of an Acoustic Development of an Acoustic Emission Test Platform with a Emission Test Platform with a Biaxial Stress Loading System Biaxial Stress Loading System

Joseph Oagaro, Shreekanth Mandayam, John L. Schmalzel and Ronnie K. Miller

Electrical & Computer Engineering201 Mullica Hill RoadGlassboro, NJ 08028

(856) 256-5333http://engineering.rowan.edu/

Progress Report for the Period August 22, 2002 – March 31, 2003

PERF 95-11 STEERING COMMITTEE MEETINGSheraton Seattle Hotel & Towers, Seattle, Washington

April 16, 2003


Presentation OutlinePresentation Outline• Project Objectives• Personnel• Test Specimens• AE Training and Quality Assurance• AE Test Platforms (Design, Development

and Results)• Version 1• Version 2• Version 3

• Summary and Future Work


Project ObjectivesProject Objectives

• Design and develop test-platforms for performing Acoustic Emission (AE) measurements on defective pipe segments under bi-axial stress conditions

• Develop empirical relations between stress and AE signal parameters


Major TasksMajor Tasks

• Specimen fabrication• Set-up for 2-D Tensile Testing• Instrumentation (AE and control) and

data acquisition set-up• AE testing: collaboration with Physical

Acoustics Corporation• Signal analysis


Conceptual Design: Conceptual Design: Test Platform Test Platform

DataAcquisition

SignalConditioning

Display/User Interface

Specimen

Load Cell

SimulatedDefect Double

ActingHydraulicRam

AESensors


Test Platform Design CriteriaTest Platform Design Criteria

• Design Challenges• Rigid Frame• Biaxial Loading of test specimen

• 30,000 psi (45,000 lbs) 1st Dimension

• 15,000 psi (22,500 lbs) 2nd Dimension• Short manufacturing time• Low cost


Project PersonnelProject Personnel

• Rowan• Dr. Shreekanth Mandayam (PI), Dr. John

Schmalzel (Co-PI), Joe Oagaro (Senior ECE), Dan Edwards (Senior ME), John Ludes (Junior ECE), Terry Lott (Junior ME)

• PAC• Dr. Ronnie K. Miller


Specimen FabricationSpecimen Fabrication• Provided by Shell• 0.5” Thick SA-516 grade 70

Steel Coupons• Simulated Cracks of

varying depths• .08”, .16”, and .32” deep

• Two sets of 3 specimens each


In-House Specimen FabricationIn-House Specimen Fabrication

• ASTM 836 steel specimens• Saw-cut defects (80% deep, 2.5” long)

Rowan Water Jet Machining Center


Collaboration with PACCollaboration with PAC

• Rowan personnel were trained on AE system at PAC on August 22, 2002

• 4-Channel AE system was delivered to Rowan on September 26, 2002

• Rowan personnel were trained on system by PAC

• Project meeting on January 30, 2003 for reviewing test results; design and test modifications suggested


AE Test PlatformsAE Test Platforms• Version 1

• Prototype Design• 13.5ksi (20,000 lbs) max load

• Version 2• Clamping Bracket Modification• 20,000ksi (30,000 lbs) max load

• Version 3• Hydraulic Rams• Full Desired load of 30ksi (45,000 lbs)


AE Test Platform: Version 1AE Test Platform: Version 1Frame

Load TransducerSpecimen

LoadingScrews

Specimen ClampingBracket


FEM AnalysisFEM Analysis

COSMOSWorks FEM analysis of clamping block


AE Test Station Construction: AE Test Station Construction: Version 1Version 1

1/24/2003


Testing ParametersTesting Parameters

• Specimen was preloaded to:• Axis 1: 10,000 lbs• Axis 2: 20,000 lbs

• AE sensors activated and test run for approximately 30 minutes

• Crack Depth 60%, Length 2.5”


AE Results: Version 1AE Results: Version 1

40

42

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50

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54

56

58

60

Amplitude (dB)

Test 1 Test 2 Test 3

Average Amplitude of Acoustic Emissions: Uniaxial vs. Biaxial

Uniaxial

Biaxial



50

55

60

65

70

75

80

85

90

Amplitude (dB)


Maximum Amplitude of Acoustic Emissions: Uniaxial vs. Biaxial Loading

Uniaxial

Biaxial



0

50

100

150

200

250

Acoustic Emissions


Total Number of Acoustic Emissions: Uniaxial vs. Biaxial

Uniaxial

Biaxial


AE Location: Version 1AE Location: Version 1


Design Limitations: Version 1Design Limitations: Version 1

• Clamping method caused deformation of specimen producing spurious AE data.• Location View shows AE Hit concentration in

proximity of clamping brackets

• Connection from load cell to specimen fixed, causing bending moment and non-uniform loading of specimen

• Inability to reach desired load



Load Transducer Specimen

LoadingScrews

Specimen ClampingBracket• New Clamping Brackets

• Pinned connections for ensure uniform loading

• Max load of 30,000 lbs


Testing ParametersTesting Parameters• AE sensors active throughout

loading of specimen

• Specimen loaded in steps of 2000 lbs up to:• Axis 1: 30,000 lbs• Axis 2: 15,000 lbs

• Signal processing to remove spurious data during loading of test platform


AE Results: Version 2AE Results: Version 2Average Amplitude of AE: Unaxial vs. Biaxial Loading

0

10

20

30

40

50

60

70


Am

pli

tud

e (d

B)

Uniaxial

Biaxial


AE Results: Version 2AE Results: Version 2Maximum Amplitude of AE: Uniaxial vs. Biaxial

82

84

86

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90

92

94

96

98

100


Am

pli

tud

e (d

B)

Uniaxial

Biaxial


AE Results: Version 2AE Results: Version 2Number of AE Hits: Unaxial vs. Biaxial

0

50

100

150

200

250

300

350

400

450


Nu

mb

er o

f H

its

Uniaxial

Biaxial


AE Location: Version 2AE Location: Version 2AE Location Plot: Biaxial Loading Test 2

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2

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12

14

0 2 4 6 8 10 12

X position (in)

Y p

ositi

on (i

n)

Biaxial

Sensor

COSMOSWorks FEM Model


Why Version 3?Why Version 3?

• Hydraulic design• Allows for increasing max load to 30 ksi• Controlled loading environment

• New clamping bracket• Single pin piece – minimizes noise



Load Transducer

Specimen

HydraulicCylinders Specimen Clamping

Bracket


Summary of ProgressSummary of Progress• Rowan personnel have been trained in AE testing

techniques by PAC• Two versions of the biaxial loading test platform

constructed – fabrication of third and final version underway

• AE tests conducted on test specimens fabricated in-house; specimens provided by Shell will be tested on Version 3

• AE signatures obtained for 1-D and 2-D loading of the test specimens indicate appreciable differences, demonstrating proof-of-concept of the technique

• Continuous interaction with PAC for quality assurance.


Future PlansFuture Plans• Develop Version 3 of the test platform withhydraulic

loading• Conduct tests on specimens provided by Shell• Parameterize AE signature differences between uni-

and bi-axial loading of test specimens• Generate calibration curves and empirical relationships

quantifying 1-D and 2-D stress effects

• Generate final report summarizing all findings• Provide recommendations for design of a pressure

vessel test platform

development of an acoustic emission test platform with a biaxial stress loading system

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