Vibrational Energy Transmission and Mode Conversion at a Corner-Junction of Square Section Rods

The low frequency reflection and transmission of vibrational energy at an L-junction of square section rods is investigated theoretically and experimentally. The theoretical description, in which thin rod theory is employed, is complete in that all modes of vibration are considered including compression, torsion, and bending both for the incident and generated waves. It is seen that bending vibration in the plane of the system is coupled to compressional waves and bending vibration normal to the plane of the system is coupled to torsional waves. The theory applies to junctions of semi-infinite rods and this condition was simulated experimentally by means of impulse response techniques in which the reflected waves were removed by truncating the time histories prior to frequency analysis. A novel combination of phase separation, time of flight methods, and filtering has allowed the various modes of vibration to be separated and the agreement between predicted and measured reflection and transmission loss, both for same mode and dissimilar mode coupling, is promising.