Abstract: Aimed at the characteristics of small thickness,light weight and lower dynamic behaviour of aeronautic gears,an idea of carrying out a structural dynamic design of the gear is proposed.The proeedures are,at first,to make detailed calculation of the gear by FEM,than,to calculate the design sensitivity of vibration modes by perturbation method, and at last to modify the structure parameters according to the locations of the design sensitivity and get a gear of good dynamic behaviour.All of these are carried out in a microcomputer.

Key words: Key words Aircraft parts, perturbation theorygear, dynamic characteristicsfinite element method, perturbation theory