[Gdeaver]

With composite structures the orientation of the fibers affect it's characteristics. One problem with pultrusions is the large majority of fibers are in the length direction. Because of this point impacts are a problem with Pultrusions. This can be partially addressed by filling the pultrusion with 2 lb, 2 part expanding foam. With pultrusions a good way to increase the point impact strength and increase the load bearing capacity is with tube in tube construction. We took a 2" 1/8 wall and a 1" 1/8 square tube pultrusion. The 1" was inserted in the 2". The space between the 2 on one end was filled with epoxy and chopped carbon fiber for 4" and bolts where set in the epoxy to mount the hinge hardware. The space between the 2 tubes was then filled with the 2 part foam with in 6" of the other end and then that end was filled with epoxy fiber mixture. The resulting structure Has point impact resistance and is stronger than going to heavy wall units and is still very light. With composite work I would strongly recommend using an amine laminating epoxy and not polyester resins. The surface hardness and strength is much better with epoxy.