n fastened together to make the frame. Using composite construction you can build a frame with fewer joints than metal construction. Fewer joints give less chance of cracks starting. Composite construction can end up being lighter than if you had made the part out of an equivalent metal. Weight savings of as much as half the equivalent metal are possible. The tensile strength of the composite frame can also be as much as twice the metal frame. It is also possible to have a composite frane that is both lighter and stronger than if you had built it out of metal. Another point of interest is that composites are corrosion resistant. Metal frames must be painted to prevent corrosion. A chip in the paint on metal tubing will result in corrosion to the frame. Composite frames dont have to be painted. If painted, flaking of paint is not a problem since the frame is naturally corrosion resistant.Composites have a low thermal expansion rate compared to metals. Metals dont maintain their dimensions as well as a composite over a certain temperature range. However some composites dont hold up in low temperatures or in temperatures above 300 degrees F. Another negative if you use composite materials is the cost. The materials to create a composite are more expensive than most metals. Steel is $.23/pound while carbon fiber is $100/pound! In order to benefit from the structural advantages of composites,you need to know the many different materials that you have to choose from to create a composite. To make a choice you need to know each of the materials strengths. Kevlar 49 is one of the reinforcing fibers. It has an ultimate strength of 525,000 psi. If you were to use pitch carbon fiber, its ultimate strength is 300,000psi. If you were to stop with these two choices, you would probably pick Kevlar 49 because its stronger. If you go on to look at more of the technical specifications you would see that carbo...
