Top Hat with Carbon or E-Glass UD's

In a top hat beam, in a boat hull for example, where the webs and part of the top hat/flange are made from e-glass and the remainder of the top hat/flange consists of e-glass or carbon ud’s and when working with the equivalent section composite beam method, does one assume that the e-glass is there just for the ride as it has a higher elongation before reaching its lower breaking strength than the stiffer higher strength e-glass or carbon ud’s?.

 

Normaly when canlculating scantlings you would check for stiffness and maximum bending moment.

Stiffnes is usualit calculated by the summation of IE and maximum bending moment is usualy calculated on the bassis od the allowable stresses in the layers of the laminate.

 

Designing any kind of beam you must make sure that the web can carry the shear loading applied by the "flanges". Without that, the webs will just tear out and leave you with a piece of carbon flapping in the breeze.

Steve