How to stress composite lugs?

[tom787]

For metallic lugs design guidelines are available (eg. Niu). However, these can not be directly used in composite lugs.

Does anybody know of design guidelines or methods to analyze composite lug?

I am analyzing a 3D composite (carbon/epoxy) lug.
This thick laminated lug (17.5 mm) has a hole with a spherical bearing installed. The lug consists of 50 plies of SM_5H_Satin fabric. The lay-up is quasi isotropic.

The analyses were performed using finite element method (I am still looking for correct 3D material values see thread327-228660). Later, we will perform physical tests to correlate the results.

The papers that are referenced in thread181-27567 are interesting but do not give sufficient answer.

Regards, Tom.

 

[SWComposites]

The only open literature references for composite lug methods that I know about are:

C. Kassapoglou, “Failure Prediction of Composite Lugs Under Axial Loads”, AIAA Journal, Vol. 41, No. 11, November 2003.

M. Wallin, “Load Response and Failure of Thick RTM Composite Lugs”, In Proceedings of ICAS 2002 Congress.

I have been dealing with composite lug analysis for the past several years. Analysis methods need to consider each potential lug failure mode: net tension, bearing, shear-out, cleavage, bending, delamination. The current methods are all essentially empirical. Test data is required to validate the methods.

 

[tom787]

It surprises me that only few articles are available.

Here's another interesting paper:

http://paginas.fe.up.pt/demegi/Avaliacao/Pp_Camanho_Mathews_99.pdf?

Professor Matthews did quite some work on composite joints a good reference is: Matthews, F. L. Joining fibre-reinforced plastics / 1987

Tom

 

[SWComposites]

Yes, there are lots of bolted joint references in the literature, some useful, most not. But lugs are very different things from typical bolted joints. Lugs are too practical and complicated for research projects, so most lug development has been done by companies, and thus the data and methods are proprietary.