TABLE OF CONTENTS Safety in the traditional "Aluminum World" has a solid foundation in service experience and empirically validated design methods. Not much of that tradition translates well to safe composite structural design. Innovation of structure (especially, for composite structure) means a steady stream of new materials, new processes and new structural concepts. Innovation also means continued introduction of new "better" materials which often makes emerging service experience inapplicable.
Traditional structural design has been focused on the "Extreme Situation" and "worst-case scenarios." Composite structure, critical for damage tolerance and sensitive to operational environment, should be focused on the "Typical Situation" and "Representative Scenarios" to avoid huge costs, long test time and large volumes of data. This could be a practical solution if coupled with uncertainty reduction, risk management, data monitoring and the use of inspection programs as a control process during service.
Tribus (1969) identifies three types of uncertainty as central to Structural Design. They are;
Uncertainty in Data (statistics);
Uncertainty in Hypothesis (model/distribution);
Uncertainty in Knowledge (nature of random phenomena).
In innovation, by its sheer nature, there is uncertainty in requirements. Existing understanding is based on interpretations of results in a "Riveted aluminum skin-stringer world." Practices at airports, repair facilities and depots change both with time and location. Even though Vice President Al Gore's "Commission on Safety in Aviation" collected and analyzed much useful data, it does not translate well into the World of Composites. The "environment" at airports change; e.g. accidental damage due to impact by construction...
