Need help with a laminate analysis problem

AI Thread Summary
Guidance is sought for calculating the load per unit width (Nx) at which a flat laminate of unidirectional carbon fiber reinforced plastic will fail, given its specific stacking sequence and ply properties. The user has already computed the Q, Qbar, and A, B, and D matrices but lacks stress and strain values to apply the Tsai-Hill criteria. Suggestions include treating the laminate as a plate bending problem, where the displacements at the interfaces of the plies must match. This approach involves ensuring boundary conditions are satisfied across the laminate stack. Assistance is requested to navigate these calculations effectively.
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Hi, I am looking for some guidance on a problem I am trying to solve on laminate analysis.
This is a flat laminate (9 plies with a thickness of 0.125mm) of unidirectional carbon fibre reinforced plastic with a stacking sequence of:
0/60/0/-60/90/-60/0/60/0.

Ply properties are as follows:

E1 = 134 GPa, E2 = 10.3 GPa, G12 = 5.1 GPa and v12 = 0.326

stress1UT = 2090 MPa, stress2UT = 97 MPa, stress1UC = -1600 MPa, stress2UC = -356 MPa and

T1UT = 114 MPa

How do I calculate Nx, the load per unit width in the 0 angle direction at which each set of plies will fail. I do not have any stress or strain values so I am unable to put this into the Tsai-Hill formulae. Is there any way I can calculate the stress and strain values? So far I have calculates the Q, Qbar and A B and D matrices. I do not know how to go further from this.
In addition to this, I need to find ultimate strength allowing for those plies which fail early.

I am not looking for plain answers, I would prefer some guidance on how to go about solving this. Any help is appreciated.
 
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Can you consider this as a plate bending problem, with a stack of plates? It would seem that each plate should bend according to the usual elastic bending model. Then you would need to require that the displacements on the top face of one plate should match those of the underside of the plate above. Then it is a matter of matching such boundary conditions through the whole stack, a bit messy, but possible in principle.
 
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