Dynamics of Periodically Stiffened Structures Using a Wave Approach.
Summary rept. Oct 67-Feb 70,
SOUTHAMPTON UNIV (ENGLAND) INST OF SOUND AND VIBRATION RESEARCH
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Vibrations of beams, plates, periodically- stiffened in one or two directions have been analysed in terms of free flexural wave- groups. Theorems relating to the free flexural waves and their propagation constants were developed and relationships with the transfer matrix theory established. Two free wave groups have been identified for rib-skin structures and an infinite number for orthogonally stiffened plates. Both free and forced plane wave propagation across the plate have been studied, the direction of propagation being varied. A PREFERRED DIRECTION EXISTS IN WHICH THE VIBRATION RESPONSE IS GREATEST. This study has also led to the development of an approximate method of determining the natural frequencies of skin-stringer structures, allowing for the frame torsional stiffnesses. Author, modified-PL