The Complementary Roles of Analysis and Testing in Aircraft Structural Substantiation

In the structural design of modern aircraft it is vital that the best possible judgment be exercised in distinguishing between those areas of the design which can be adequately proven by analysis and those which are best developed and substantiated by test. Knowledge gained over the past few years from the design and development of two large jet cargo transport aircraft, as well as service experience from other transport aircraft, is reviewed for the purpose of gaining additional insight into this very complex problem. The overall structural design process, involving determination of external loads and stiffness requirements as well as detail and fatigue substantiation, is discussed. An effort is made to summarize some of the more important advancements in analysis techniques which have come about as a result of computerization. The prospects for further improvements in these techniques are discussed. Data is also presented to illustrate the role of design development by testing and the relative merits of this approach in lieu of analysis. Finally, a correlation of analysis and test data derived from airframe component and full scale testing is presented and discussed