Specific Composite Design Factors

[40818]

With reference to the use of composites within the aerospace industry, has anybody any experience of the use (and rationale for) additional design safety factors above and beyond proof (1.25) and ultimate (1.5)?

 

[berkshire]

At one time the FAA used to ask for an additional 1.5 material variation factor to cover quality errors such as people losing count of the number of layers in a lay up and missing one, or incorrectly mixing resins and hardeners, or curing same at the wrong temperature.
I think adequate quality control measures have resulted in them backing away from this requirement.
Other people in the industry can comment on this.
B.E.

 

[ESPcomposites]

I can't speak about the past, but the standard metal 1.0 limit load and 1.5 ultimate load factors apply for commercial composite aircraft. For military aircraft it may be program specific. Not familiar with the 1.25 proof load though.

Brian

http://www.espcomposites.com