Hガタ ボウ ワクグミ ノ シンドウ

The free vibrations of the H-type frame works consisting of three straight bars are studied by the Lagrangian-minimizing-method. In the case of the frame work vibrating in its own plane, there are the lateral and extensional vibrations and no torsional one. In the case of the frame work moving perpendicularly to its plane, there are only the lateral and torsional ones. In both cases, the normal vibrations can be classified to four groups according to the type of the displacements of the bars in each normal vibration, since there are two planes of symmetry in the frame work. The Lagrangian represented by the suitable combinations of the unknown boundary values is minimized and consequently the frequency equations for these groups are obtained respectively. In this paper the numerical calculation of the frequencies is confined to the vibrations perpendicular to the plane of the frame work. These numerical determinations are denoted in graphs