MMPDS (Old HDBK 5) Joint Yield Load

[mcclain]

Joint yield load is defined as the load at 0.04D offset on the load deflection curve from a joint test.

Does anyone know where the 0.04D assumption came from?
Is there a rationale?

Thanks

 

[edbgtr]

As I understand it, the definition of yield load of the fastener in the hole, is 0.02D deflection on each of the two fasteners used in the test. The 0.04D is the sum of the hole deformations in the test. This load, when multiplied by 1.5, usually produces a result which is just under the ultimate test load. This lower load is often used in company manuals (and in design) in preference to the MMPDS ultimate joint test load.