| 摘要 |
PURPOSE:To approximate the initial speed of ball hitting to the max. by increasing the repulsion coefft. when the tennis racket hits a ball. CONSTITUTION:Rigidity is so distributed that the rigidity is maximized in a position of 0.14 to 0.70L from a frame top (21a) with respect to the overall length (L) of the frame to make the out-of-surface secondary natural vibration frequency measured under a free restraining condition coincide with the primary natural vibration frequency of the tennis ball measured under the free restraining condition existing in a range from 300 to 450Hz. The out-of-surface primary natural vibration frequency of the tennis racket measured under the free restraining condition is set at >=0.4 to t<1 times the out-of-surface secondary natural vibration frequency. |
