1. What are advanced composites?
Advanced composites utilize a combination of resins and fibers, customarily carbon/graphite, kevlar, or fiberglass with an epoxy resin. The fibers provide the high stiffness, while the surrounding polymer resin matrix holds the structure together, allowing infinite design capability. Although composites can be made from almost any fiber, most products are made with carbon fibers because they offer the highest stiffness-to-weight ratio, and very low coefficient of thermal expansion. Composites are resistant to fatigue and harsh environments, are easily repairable, have negligible creep and look great too.
2. How do carbon composites compare with metals?
Generally, carbon composites are two thirds the weight of aluminum, and two and a half times as stiff.
Some data for a typical epoxy and intermediate-modulus fiber in a uni directional composite (Hercules IM7/8551) at 77 degrees F., in US units, is as follows:
|0 degree tensile strength||400,000 psi|
|0 degree tensile modulus||24.5 x 106 psi|
|0 degree tensile elongation||1.62 %|
|90 degree tensile strength||11,100 psi|
|90 degree tensile modulus||1.20 x 105 psi|
|90 degree tensile elongation||0.92 %|
|0 degree compression strength||240,000 psi|
|0 degree compression modulus||21.5 x 105 psi|
|0 degree short beam shear strength:||14,500 psi|
|cured ply thickness||0.0055 in.|
|fiber volume||62 %|
|Fiber/resin areal weight @ typical 35% resin content||0.0443 lb/ft2|
3. What is the CTE of carbon composites?
The coefficient of thermal extansion (CTE) of carbon composites is less than that of Invar. A CTE of zero can be achieved with high modulus materials.
4. Are composites conductive?
Carbon is conductive, the resin matrix is essentially non conductive.
5. Where can I learn more about composites?
Other than the obvious answer, contact us to learn more about what we can do for you, you can learn about composites from the following sources:
- The High-Performance Composites Source Book In Plainview NY, USA. phone (303) 467-1776, fax (303) 467-1777.
- The Handbook of Composites edt by George Lubin. Van Nostrand Reinhold Co. 135 W. 50th St. NY,NY, USA 10020
- Composites Fabricators Association. In Arlington, VA, USA, phone 703-524-3332