A Modified Wedge Method for exciting Shear Modes in Isotropic Media

THE wedge method developed by Bhagavantam and Bhimasenachar 1 has been very useful in the determination of elastic constants of solids. But very often it is found to be difficult to excite and identify the shear modes for the transmission maxima, as they are very weak and are of the same order of intensity as the spurious frequencies of the wedge. However, it has been pointed out 2 that, if small thin specimens are used, shear modes could also be excited, although feebly, due to edge coupling. Recently 3 , it has been reported that shear modes cannot be excited in rocks which are coarse-grained and heterogeneous in composition. The method presented here describes a simple modification of the wedge method for exciting and identifying easily only the shear modes in isotropic media and thus overcoming the difficulties inherent in the normal wedge method.