APPLICATION OF NONLINEAR PROGRAMMING TECHNIQUES TO DYNAMIC CORRELATION AND DESIGN OF HELICOPTER STRUCTURES

Reference 1 described two recent efforts at Sikorsky in the field of airframe structural dynamics, both of which were aided by the new program tool PAREDYM: (1) improving the current finite element model of the UH-60A to make it agree closely with shake test data so that future design changes, and their effects on aircraft dynamics, can be correctly assessed, and (2) incorporating inherent low vibratory response into an airframe design throughout the design cycle. The present paper presents recent progress made in both of these areas. Analytical and test results are presented showing the influence of the suspension system on the modal properties of the UH-60A airframe. Results are also presented showing the effect of introducing minimum-weight-change and design-variable constraints into the low-vibration design-optimization problem.