Failure Conditions 1

[hyeh]

In looking at failure conditions, should the resulting stresses be compared against Ftu or Fty. Is the criteria different between military and commercial programs.

Thanks.

 

[rb1957]

as the FARs direct, after a failure has occurred, the ultimate factor of safety (1.5) doesn't need to be applied.
but your allowables would still be ultimate ...

let's see if this helps ...
before failure limit load yield allowables
before failure ultimate load (=1.5*limit) ultimate allowables
after failure limit load ultimate allowables

 

[hyeh]

Thanks RB1957 that is what I thought. Can you point me to that paragraph in the FAR (25 I assume).

Thanks again.

 

[rb1957]

25.303