1. Air Coupled Ultrasonic Imaging For Non-Destructive Inspection GTL Ultrasonics David Lavery Mario Malavé Andrew Ray Final Design Report April 23, 2009

2. Problem Overview Design Alternatives Chosen Design Detail Market Analysis Transducer Performance Circuitry Performance Software Performance Final Design Specifications Unresolved Problems Probable Solutions Team Performance Review

3. Air-Coupled Ultrasonics Device for non-destructive inspection of materials Using novel polymer foam transducer Incorporate new transducer material into device to improve performance

4. Objectives Develop a working ACU-NDI system using a novel transducer material – Complete Reduce Cost – Complete Increase Efficiency – Partially Complete Mobile System – Incomplete

5. Unforeseen Obstacles Electromagnetic Interference – Overcome using circuit timing Poorly Conductive Transducer Surface – Overcome using compression contacts Highly Directional Signal – Overcome at cost of mobility High Impedance Between Air and Imaged Objects – Through Transmission Abandoned – Pulse-Echo Setup Used

6. Design Alternatives Cylindrical Housing Portability Limited Circuitry Space Poor Electrical Connections

7. Design Alternatives Plate Mounted Portability Electrical Connection Issue Resolved Poor Stability Highly Variable Performance

8. Chosen Design Best Performance Marginal Portability Expandable Circuitry

9. Design Tradeoffs Excess Wire Length versus Expandability – Potential for unwanted interference – Ease of circuitry redesign/expansion Portability versus Stability – Highly directional signal – Difficult to obtain useful data in handheld operation

10. 7.5mm Plexiglas Copper Tape BNC Fitting Transducer Foam

11. Parts List Item #NameMaterialDescription 1 Base Plate7.5mm Plexiglas Forms base of the transducer device 2 Side Support7.5mm Plexiglas Supports front plate and back support 3 Back Support7.5mm Plexiglas Holds BNC connector in place 4 Front Plate7.5mm Plexiglas Mounting location for transducer and circuitry 5 Compression Plate7.5mm Plexiglas Compression connection for transducer/electronics 6 BNC ConnectorMultiple Connects transducer to user output device 7 Copper TapeCopper Ground connection of piezoactive transducer 8 TransducerPolymer Foam Live connection of piezoactive transducer

12. Transducer Performance High Quasi-Static Piezoactive coefficient – 25-700pC/N Low Acoustic Impedance – 0.028MRayl

13. Transducer Performance 200V 300kHz 100pulse/sec – Maximum Unimpeded Transmission Distance 356.3mm – Peak-Peak Voltage Received 20mV – Minimal Signal Distortion

14. Silver Surface Etching Photolithography Produces Exact Shapes Proof of Concept Not Used for Transducers

15. Circuitry Alternatives Amplifier and Band Pass Filter – Eliminates Background Noise – High Gain – More Complex Circuitry

16. Circuitry Alternatives Amplifier(s) Without Filters – High Gain – Less Complex Circuitry – Noise Amplified With Signal

17. Performance Comparison AmplifierFilter - Amplifier

18. Chosen Circuitry Single Amplifier – 35dB Gain – Less Complex - Fewer Failures – Fewer Points to Introduce Interference

19. Amplifier Parts List Item #NameDescription U1 Op-Amp Analog Devices AD8001 800MHz GBW Operational Amplifier R1 Resistor 180k Axial Lead Resistor R2 Resistor 2k Axial Lead Resistor Conn1 DIP Socket Mounting for Op-Amp to Allow Quick Replacement if Failure Conn2 Sockets Sockets for Resistor R1 to Allow for Changes to Alter Gain PCB Proto Board PCB to Mount Components On

20. Connection Alternatives Single Adhesive Tape Contact – Simple to Construct – Prone to Poor Connection – Impossible to Verify Contact

21. Connection Alternatives Double Adhesive Tape Contacts – Simple to Construct – Prone to Poor Connection – Possible to Verify Connection

22. Connection Alternatives Double Mechanical Contact – Complex to Construct – Unlikely to Lose Connection – Possible to Verify Contact

23. Connection Alternatives Single Mechanical Contact – Less Complex to Construct – Unlikely to Lose Connection – Impossible to Verify Contact

24. Mechanical Connection

26. Connection Resistance Mechanical Connections – 6.3 Ω, 5.8 Ω, 4.5 Ω, 4.9 Ω Adhesive Connections – 368K Ω, 630 Ω, ∞ Ω, ∞ Ω

27. Chosen Connection Design Double Mechanical Contact – Ability to Check Connection – Low Connection Resistance – Higher Performance – Greater Reliability

28. Software Performance Wavelet Transform vs. Fourier Transform Advantages of the Wavelet Transform Ultrasonic Applications Analyzing Received Signal

29. Fourier Transform Cross products of changing complex exponentials (varying sinusoids) Continuous Wavelet Transform Cross products of a scaled and shifted wavelet Wavelet Transform vs. Fourier Transform

30. Predefined Wavelets

31. Scaled Wavelet

32. Generated Output Fourier Transform (Spectrum) Wavelet Transform (Scalogram)

33. Advantages of the Wavelet Transform Detect transients in a signal Analyze non-stationary signals – All order statistics of the signal are changing with time Detect changing statistics even in the presents of noise – If the noise remains constant throughout the process (stationary noise) Scalogram not depended on a windowing – Short-Time Fourier Transform (STFT) uses window to generate a spectrogram

34. STFT Example (T=25ms)

35. STFT Example (T=1000ms)

36. Wavelet Transform Example 1

37. Wavelet Transform Example 2

38. Ultrasonic Applications Pass through transducers – Received signal will contain frequency components that change with time Transient region detection – This can be used to characterize different materials – Due to different impedances of the materials

39. Analyzing Received Signal LabVIEW Analysis of reflected data Data extracted from the oscilloscope via Ethernet port Analyzed with the “Mexican Hat” wavelet (reflection configuration)

40. Analyzing Received Signal 1

41. Analyzing Received Signal 2

42. Results Emitting on different surfaces using reflection – Wavelet Analysis showed slight statistical changes – Amplitude changes are present in the ultrasonic signal Wavelet transform results can be improved if a pass through transducer is used

43. Damping Detection LabVIEW Analysis of reflected data Detect amplitude changes with configurable thresholds

44. Analyzing Received Signal

45. Final Specifications Refer to Specs Handout Key Specifications – 356.3mm transmissible distance – 7mm flaw detected 10 out of 10 times – 2mm flaw detected 2 out of 10 times

46. Unresolved Issues Pass-through capability – Leads to software issues Compact mobile system – As a result of meeting other performance specifications

47. Probable Solutions Pass-through – Increase power to transducer – Identify better material – Circuitry design Mobile System – Add internal storage capacity – Create pass-through capability

48. Market Analysis Frequently used couplants used for transmission – Oil, glycerin, and water – Success with air can open a new market of devices Possible Device Users – Aviation/Aerospace companies; Boeing, Lockheed Martin, NASA NASA Space Shuttle – Currently uses Laser Dynamic Range Imager (LDRI) Only provides superficial data Air Coupled Ultrasonics (ACU) provides information deeper than the surface

49. Updated Parts Cost Table Part DescriptionQuantityUnit PricePrice 2'x2' Printed Circuit Board (PCB)2$3.45$6.90 Operational Amplifiers (Op-amp)3$1.25$3.75 Resistor10$0.90$9.00 Capacitor5$0.95$4.75 BNC Connectors4$5.00$20.00 200mm x 200mm Plexiglas Sheet1$10.00 Cellular Polypropylene Foam (1m)1$15.00 DC Power Supply (400 W)1$100.00 Cable (10 ft BNC)1$20.00 Mounting Hardware Kit1$20.00 LabVIEW Software (Student Version)1$80.00 Project Total $289.40

50. Cost Analysis 60 Engineering hour for each group member –$50/hr give a cost of $9000 in labor 21.7% profit at a sales price of 2,500 ($541 per unit sold)

51. Team Performance Deviations from Schedule – Etching Research – Transducer Construction – Circuit Design Obstacles to Achievement – Lower Power Transducer – Surface Reflection Used

52. Major Deviations

53. Works Cited http://www.mathworks.com http://www.conceptualwavelets.com/