Ceramic solids can be made to resonate mechanically by vibrating them at specific frequencies dependent on their physical properties and dimensions. The resulting spectrum contains vast information regarding the object's elastic properties, internal friction, structural integrity and shape. Extracting and interpreting this information, however, has proven to be most challenging. It has only recently been made technologically possible. This ability is of immense importance because ceramics are either more difficult or impossible to investigate with most non-destructive inspection techniques which were developed for metals. In addition, other modern materials such as textured alloys, single crystal materials and anisotropic composites require more than the usual pair of elastic moduli to describe their physical properties. That is why more traditional dynamic modulus systems require cumbersome, repetitive tests, on many samples, to fully characterize a material. The resonant ultrasound spectroscopy (RUS) technique, originally developed at Los Alamos National Laboratory, and expanded by Quatro Corporation, can provide the full anisotropic elastic tensor with unprecedented speed and accuracy. The simplest application of RUS is to the spherical geometry, however the technique is applicable to a variety of symmetrical shapes including cylinders, cones and rectangular parallelepipeds. The case to be cited, in this paper, is the RUS evaluation to ceramic cones, and its subsequent application to the sorting of precision parts.
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