TABLE OF CONTENTS The requirements and objectives of a "new" design of composite structure should be analyzed in detail before a rational design process can be started. Traditionally, even including the latest generation jetliners, the safety aspects of structural design has been addressed in terms of factors of safety, margins of safety and allowable-design values with statistical basis and relying heavily on "Service experience."
The next generation commercial jetliners, based on composites innovation, cannot "lean on", service experience for a large portion of the "primary structure", including all heavily loaded structures. So, modern innovative designs have to look for other ways to achieve the safety goals required. One way is to establish explicit safety constraints on the structural design process, and that requires numerical, practical, and realistic measures of levels of safety.
These measures should be tied to the overall vehicle safety requirements, a set of special, consistent contributions, so that all the factors that influence vehicle safety can be accounted for. This chapter shows a practical path toward describing how to ensure the structural safety performance in an environment of innovation.
The fundamental measure can be defined by the concept of one unsafe flight in n flights founded on the idea "Undetected loss of integrity."
The overall vehicle safety objective can be formulated in many ways, but it is hard to imagine a case of more direct value than:
"One Unsafe Flight out of 100 000 Flights:"
We will analyze the detail objectives in the following sections...
