| 摘要 |
Applicant's invention defines an improved electromagnetic acoustic transducer (EMAT) for monitoring stress in an underlying workpiece. The EMATs are provided with positioning pins for fixing the registration of the EMAT relative to the workpiece. The bottom contact surface of the EMAT may be altered geometrically or provided with a friction reducing means, such as a wheel assembly, to minimize contact surface area and thus unwanted frictional influences caused by deformation of the workpiece under the EMAT. An apparatus for reliably positioning the EMATs above a workpiece is also disclosed, said apparatus comprising an actuating means which by a linkage mechanism lowers or raises at least one EMAT into position, further allowing access to the positioning pins for applying the necessary force to anchor the EMATs to the workpiece.
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