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II.1.10.17 Puck criterion

This criterion is adapted to the qualification of laminates with unidirectional plies. This criterion distinguishes two failure modes: one fiber failure mode in direction 1 and one matrix failure mode. Three versions of the Puck criterion are distinguished.

The first version of Puck failure index is calculated as follows:

FIPuck = max ⁡ ( | σ11 σ11all | , ( σ22 σ22all ) 2 + ( τ12 τ12all ) 2) ,

in which the allowables σ11all and σ22all depend on the signs of σ11 and σ22 respectively. Ply passes the failure criterion if the two following conditions are satisfied

|σ11| ≤ σ11all,

( σ22 σ22all ) 2 + ( τ12 τ12all ) 2 ≤ 1.

The reserve factor is simply given by:

RFPuck = 1 FoS ⋅ max ⁡ ( | σ11 σ11all | , ( σ22 σ22all ) 2 + ( τ12 τ12all ) 2) ,

and the strength ratio is given by:

SRPuck = FoS ⋅ max ⁡ ( | σ11 σ11all | , ( σ22 σ22all ) 2 + ( τ12 τ12all ) 2) .

This criterion is referred to as “Puck” criterion in FeResPost.