Load transfer calculation in multi-row fasteners of CFRP composite joints under biaxial loading

[RKAero]

I am working on strength assessment of composite structural repair using lap joint. I am using 1D approach where I calculate fastener loads in each bolt row by hand calculations (Not FEM based). This is a very conservative approach as I am considering the max loads in the entire repair area. However, to reduce the conservatism and estimate the loads closer to FE, I am looking forward to extend this method to consider the biaxial loading to calculate the fastener loads more accurately. Can anybody suggest how to do this.

 

[FastMouse]

I guess that we are talking about something like a cut-out and reinforcing plate. First approach:
● Assume that everything is linear.
● Assume fastener tension forces are negligible.
● Perform 1D joint analyses in the circumferential and longitudinal directions.
● Assess the total fastener forces using vector addition of the resulting fastener force components in the circ. and long. directions.

...or are you already at this stage and looking for more?

 

[FastMouse]

I reread my posting. Oops, it may not have been clear! Apologies.

I was thinking about a composite fuselage skin with damage being repaired by removal of the damaged material and subsequent reinforcement of the area using a metallic doubler. "Everything is linear" means everything is elastic. The different elastic properties of the fuselage skin in the circumferential & longitudinal directions need to be taken into account, of course.

Best wishes!