This month's articles focus on Ultrasonic Transducers and Arrays, generated by piezoelectric or electromagnetic (EMAT). As usual, this will be the theme of our discussion. If you are interested in other ultrasonic testing topics, don't hesitate to discuss them on this forum as well.

We are pleased to introduce this month Rainer Meier and Gerard Fleury as our experts for this month. They will serve as coordinators for comments on their areas of expertise for the March 1998 Forum of NDTnet. Both are current Virtual Session Chairman and will serve on the 'Ask the Experts' panel.

Rainer Meier Siemens KWU Homepage - - On NDTnet

Mr. Meier's opening message:
The electromagnetic generation of ultrasound requires good conductivity in the material that has to be inspected. The sound generation is very efficient in ferromagnetic materials and in highly conductive materials like aluminum. In materials such as stainless steel or nickel-based alloys the sound generation is usually sufficient. The most significant advantage of EMAT is its ability to generate horizontal polarized shear waves (SH-waves). Other advantages are sound generation without couplant and the possibility of using the EMAT-principle at higher temperatures. The use of SH-waves shows important advantages compared with conventional wave modes:

• propagation of a pure wave mode without energy loss due to wave conversion or dispersion and without unambiguous echoes caused by unexpected wave modes
• corner effect delivers a good echo from the probe's far surface over the whole range of incidence angles
• less interference with the weld geometry in coarse-grained materials with directed grain structures (stainless steel and dissimilar welds)
• sensitivity for special material properties like texture, etc.

Gerard Fleury Imasonic Homepage - - On NDTnet

Mr. Fleury's opening message:
Current Inspection performance needs vary greatly. Although standard transducers achieve satisfactory results for some applications, there is an increasing demand for new approaches and new features. Transducer design and production according to the specific functionality of each inspection is one way to accomplish this; the use of phased array transducers with variable characteristics, notably beam focusing and beam steering, is another. Articles from TECNATOM (SPAIN) and UPPSALA UNIVERSITY (SWEDEN) illustrate recent developments using innovative transducers.

Related articles:
New Incoming Forum Article (16.3.98)
Customised Design of Transducers for Non-destructive Testing
Rémi Berriet*, Steve Mahaut**; *IMASONIC, **CEA/CEREM
Ultrasonic Inspection of Copper Canisters using Phase Arrays
T. Stepinski, P. Wu, E. Martinez, Uppsala University
Turbine Blade Attachment In Service Inspection through the Central Bore using Ultrasonic Array Technology
A. Tanarro; F. Godinez; P. Serrano (TECNATOM,S.A.- MADRID-Spain)
Ultrasonic Inspection of Complex Nozzles - Application of new Technologies
A. Tanarro and A. Garcia (TECNATOM,S.A.-MADRID-Spain)

Now it's your turn, let's start our discussion.
Your personnel question could be answered.