Toward Understanding the Impact of Bulk Residual Stress On the Life, Weight and Cost of Primary Aircraft Structure

A variety of advanced material / structural concepts are being developed by, or with the support of airframe manufacturers who are in pursuit of enhanced performance at reduced cost.  One of the more promising concepts, and one that has already been adopted for a number of high profile applications, is the unitization / integration of multiple, machined and subsequently assembled parts, into a single monolithic component.  When this is done with large monolithic forgings, the presence of bulk residual stresses must be addressed during design.

This presentation will describe methods for the explicit inclusion of bulk residual stresses in design analysis (specifically in fatigue life analysis).  The life versus weight optimization that this inclusion enables will be described for several aircraft bulkheads.  Finally, current results from ongoing weight and cost impact studies will be presented.