LONGITUDINAL STANDING WAVES IN COMPOUND BARS AND RODS

By means of the finite element method the basic behaviour of longitudi nal standing waves in bars an rods composed of layers with different m aterials is studied. The specimens investigated are of finite length a nd two materials with considerably different velocities of sound are s elected as model materials. Excitation of the waves is performed by th e application of cyclic forces at the end of the specimens. The result s of the numerical calculations are checked by the experiment. A high power ultrasonic fatigue apparatus operating at a frequency of approxi mately 20 kHz is employed for the generation of the mechanical waves. Relevance of the problem to applications, especially fatigue testing a t high frequencies, is given by extending the study to the calculation of the resulting stress distributions.