This paper presents the application of Lamb waves to detect and locate laminar damages using a beam forming imaging methodology. Beam forming is using a network of transducers that are used to sequentially scan the structure before and after the presence of damage by transmitting and receiving guided wave pulses. An image of the damage is reconstructed by analysing the cross correlation of the scatter signal with the excitation pulse and enables the detection and location of potential damage areas. The results of simulation and experimental studies show that the method enables the reliable detection of structural damages with locating inaccuracies in the order of a few millimeters within inspection areas of 300 x 300 mm2 using a transducer network of only four transducer elements.

Torsional and bending mode vibrations of a hollow cylinder shall be used for combined measurement of density and viscosity of a fluid. The employment of two different vibration modes has the advantage that modes with good sensitivity for either density or viscosity measurements can be used. For a detailed discussion of the dependencies of the sensitivity, a description of the fluid forces and a model of the sensor are required. Analytical solutions for the fluid forces acting on an oscillating cylindrical structure usually consider a two-dimensional situation. FEM simulations are performed in order to investigate the suitability of such solutions in order to describe fluid forces in a three-dimensional situation and for different bending modes. For the case at hand, an analytical relationship between the resonance frequency and the density of the liquid can be formulated. This analytical relationship forms a valuable basis for further investigations.

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