Comparison of CF mechanical properties vs other materials
Summary
CF + epoxy (2:1 by weight…professional layup vs 1:1 more typical) has strength and stiffness about half of that of the pure fiber; epoxy and fiber have almost the same density. CF + epoxy has strength and stiffness about ten times that of aluminum, and a density about half that of aluminum. So per weight, CF + epoxy has about 20x strength and stiffness of that of aluminum.
Examples
Cross sectional area of CF + epoxy needed to support 1000 lbs (at tensile failure): 1000 lbs/200x$10^3$ psi = 0.005 sq in, or the area of a rod about 0.1 in in diameter. If we include a generous safety margin of a factor of 10 (less than ideal layup and orientation of fibers), the area of a rod about 1/4" diameter. Metric: 400 kg supported rod with diameter of 6mm.
Thickness of a 1" wide CF + epoxy strip needed to support 1000 lbs (at tensile failure): 0.005 in. If we include a safety margin of a factor of 10, the thickness is 0.05 in. By comparison, 5.8oz 2x2 twill has a thickness of 0.008, so a 1" single layer strip in epoxy would hold about 150 lbs in tension (with safety factor or 10). Metric: 400 kg supported by 3 cm wide twill strip: Thickness after 10x safety margin is 1 mm.
Graphlite Carbon rod properties and uses in wing spars Tensile strength 320 ksi. Best advantage is in compressive strength: almost 5x that of typicial CF layup, which has waviness in the fiber alignment. Aircraftspruce . Complete modern specs
