Structural Health Monitoring (SHM) using torsional guided wave EMATs
| Autor: | Cegla, FB, Herdovics, B |
|---|---|
| Přispěvatelé: | Engineering & Physical Science Research Council (EPSRC) |
| Rok vydání: | 2016 |
| Předmět: |
Technology
REFLECTION Science & Technology torsional wave structural health monitoring PIPE INSPECTION STABILITY electromagnetic acoustic transducer baseline subtraction Engineering Multidisciplinary Acoustics 09 Engineering Engineering EMAT ARRAY MAGNETOSTRICTIVE TRANSDUCER Guided wave MODE NOTCHES Instruments & Instrumentation |
| Popis: | Torsional guided wave inspection is widely used for pipeline inspection. Most commonly piezoelectric and magnetostrictive transducers are used to generate torsional guided waves. These types of transducers require bonding or mechanical contact to the pipe which can result in changes over time which are undesirable for Structural Health Monitoring. This paper presents a non-contact Lorentz force based Electromagnetic Acoustic Transducer for torsional guided wave monitoring of pipelines. First, the excitation mechanism of the transducer is simulated by analyzing the eddy current and the static magnetic field using the finite element method. An EMAT transformer model is presented which describes the eddy current generation transfer function and the ultrasound excitation. Independently simulated eddy current and magnetic fields are used to calculate the Lorentz force that an EMAT array induces on the surface of a 3 inch schedule 40 pipe and an explicit finite element solver is then used to simulate the elastic wave propagation in the pipe. Then, the reception mechanism and the expected received signal levels are discussed. The construction of an experimental transducer is described and measurement results from the transducer setup are presented. The measured and modeled performance agree well. Finally, a monitoring example is presented where an artificial defect with 3% reflection coefficient is introduced and successfully detected with the designed sensor. |
| Databáze: | OpenAIRE |
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