Ultrasonic Guided Wave Applications Joseph L. Rose Penn State University April 29-30, 2013 2013 Center for Acoustics and Vibrations meeting
What is a Guided Wave? (Guided wave requires boundary for propagation such as plates, rods, pipes/tubes, multi layer structures.)
Recent Breakthroughs New understanding and interpretation of guided wave mechanics Computational efficiency available today Often no other inspection possibility for today s aging infrastructure Successful Commercialization in progress 3
Principal Benefits of Guided Waves 100% inspection coverage Inspection over long distances from a single probe position. Ability to inspect hidden structures and structures under water, coatings, soil insulations, and concrete. Cost effectiveness because of inspection simplicity and speed.
Ultrasonic Guided Wave Actuator Designs - Could be single or multiple element 1. Piezoelectric 2. Lorentz Force Electromagnetic 3. Magnetostrictive 4. Air Coupled 5. Laser Beam 6. Controlled Mechanical Impact
Hybrid Analytical FEM Computation Dispersion Curve Computation Wave Structure Analysis Actuator Design Boundary Conditions for FEM Models Key Experiments FEM Computation System Design The Hybrid Analytical FEM Approach for Solving Guided Wave Problems (Sample problems solved using this approach includes transverse cracking in rail, finding weak interfaces in bonded structures, handling water loaded structures, ice detection, and de-icing of rotorcraft and fixed wing aircraft.)
Transverse crack detection in the head of a rail Figure D-6. Phase velocity dispersion curve for rail. 7
Figure D-8. Rail coverage as a function of mode selection. 8
Frequency and other Tuning Possibilities (a) (b) Figure D-14. Guided wave propagation in elbowed pipes with different sizes. 9
Ice detection with ultrasonic guided waves and De-icing (a) No ultrasonic ice protection (b) With ultrasonic ice protection Figure D-15. Photograph showing a airfoil leading edges. Without ultrasonic ice protection a 0.431 ice layer accreted to the leading edge. 10
Coating delamination and axial crack detection Figure D-24: EMAT configuration to inspect from the inside of a pipe. 11
Figure D-23: Coating disbond detection using circumferential shear horitzontal guided waves (Mode: SH0, Frequency: 130kHz, Source: EMAT, Pipe: 20in S10 with coal tar coating). 12
Guided Wave Active Focusing in Pipe FE Simulation Results Transducer array located at pipe end Array can be segmented into 4 or 8 channels. Time delays are applied. 1 2 3 4 5 Focus beam forming
Defect 3 Defect 1 Defect 2 Defect Defect Defect Defect 1 Defect 3 Defect 2 Figure 21-20: Sample Fast Frequency Analysis plot, Time Domain waveform, and flattened pipe image showing defects and other features. 14
Ultrasonic Guided Wave Tomography for an Impacted Composite Plate 2 nd shot Target 1 st shot (Every sensor sends a special guided wave mode and frequency information to every other sensor to develop image reconstruction.)
Water loaded structures (a) (b) Figure D-12. Tomography result of the water loaded steed plate with a corrosion defect (a) A1 mode at 2.5 MHz (b) S1 mode at 2.8 MHz. (a) Poor result- sees corrosion and water (b) Excellent result- sees corrosion only 16
Guided Wave Phased Array Imaging in Plates Figure 21-16: Conceptual drawing of a circular phased array probe geometry and a snapshot from a numerical simulation showing beam steering in one direction upon applying the appropriate time delays to a circular phased array sensor geometry. Beam steering in anisotropic material needs special attention because of skew effects. Multi mode inspection might be necessary. 17
Guided Wave Through Transmission Dual Probe Imaging Application Example: Guided waves are used to send energy along aircraft repair patch bondlines to determine bond integrity. Repair Patch
Ultrasonic Vibrations A special multi-element annular array probe to induce controlled ultrasonic vibrations from specialized transient ultrasonic guided wave mode and frequency points on a dispersion curve has been developed at PSU to provide a signature of a component suitable for quality control and inspection.
Concluding Remarks The key to success in Guided wave Application is the Actuator Design as illustrated in many of the examples presented today. The design depends on proper Mode and frequency choice to achieve appropriate sensitivity, resolution and/or penetration power for a specific problem statement.