Fiber composites since 1985

Guide | The correct handling of CFRP Carbon

Properties of CFRP Carbon

CFRP - Carbon Fiber Reinforced Plastic
Car­bon Fiber Rein­forced Plas­tic (CFRP)

Car­bon fiber mate­ri­als (CFRP) are mate­ri­als with out­stand­ing prop­er­ties: light, excep­tion­al­ly stiff, of high strength, fatigue and cor­ro­sion resis­tant. How­ev­er, due to the spe­cial mate­r­i­al prop­er­ties of the fiber, a few mea­sures should be tak­en to pre­serve these advan­tages for as long as pos­si­ble. Knowl­edge of the com­po­si­tion and struc­ture of a car­bon mate­r­i­al allows pre­dic­tion of the max­i­mum load capac­i­ty val­ues that can be achieved and the main­te­nance mea­sures nec­es­sary to main­tain them. Processed in a com­pos­ite part, the fiber is only one of the main load-bear­ing com­po­nents; the con­nec­tion of the fibers and their rel­a­tive posi­tion­ing to each oth­er are pro­vid­ed by the resin sys­tem used.

Espe­cial­ly for struc­tural­ly load-bear­ing (stressed) appli­ca­tions, the use of epoxy as a resin sys­tem is still the best choice. As a result, excel­lent fiber wet­ting, high strength and load-bear­ing capac­i­ty are achieved with the low­est pos­si­ble mate­r­i­al usage. To main­tain the ben­e­fits of a car­bon com­pos­ite over the long term, the fol­low­ing rec­om­men­da­tions can be made:

  • Avoid strong heat­ing of the com­po­nent. The dark sur­faces of car­bon in par­tic­u­lar absorb a lot of ener­gy from sun­light, for exam­ple, and devel­op a great deal of heat as a result. Con­trolled post-cured com­pos­ite com­po­nents that are exposed to high tem­per­a­tures in the process also lose some of their fatigue strength when exposed to heat.
  • Epoxy resins are not UV resis­tant. Pro­longed intense expo­sure to UV rays attacks the mol­e­c­u­lar struc­ture of the epoxy and alters its phys­i­cal properties.
  • Attacked epoxy has a ‘chalky’ char­ac­ter and has low fiber adhe­sion. Should it sep­a­rate from the bond, the embed­ded fiber is exposed to the weath­er with­out
    espe­cial­ly mois­ture can then pen­e­trate the com­pos­ite and fur­ther weak­en the strength of the lam­i­nate. To avoid this pos­si­ble process, coat­ing or paint­ing the car­bon com­po­nent is rec­om­mend­ed. UV-resis­tant polyurethane coat­ings, which are also avail­able as a clear mate­r­i­al, are ide­al for this pur­pose.
    Car­bon mate­ri­als, like met­als, have good elec­tri­cal con­duc­tiv­i­ty. Accord­ing­ly, they (espe­cial­ly masts!) should be pro­vid­ed with suf­fi­cient ground­ing if pos­si­ble or necessary.
  • Anoth­er effect of the con­duc­tiv­i­ty is the increased cor­ro­sion of direct­ly con­nect­ed met­al objects on car­bon, espe­cial­ly sus­cep­ti­ble of course alu­minum, which acts as an anode on car­bon and thus cor­rodes strong­ly. For pro­tec­tion, insu­la­tion with a non-con­duc­tor is always rec­om­mend­ed, i.e. the use of plas­tic seals, or plas­tic fit­tings. Some hard chairs also weath­er to a greater or less­er extent in direct con­tact with car­bon, but the cor­ro­sion decreas­es sig­nif­i­cant­ly as the grade of the steel increases.
  • A major advan­tage of fiber com­pos­ites is the pos­si­ble ori­en­ta­tion of the fiber direc­tions accord­ing to the expect­ed force appli­ca­tions. Due to the high stiff­ness of the car­bon fiber along the fiber direc­tion, opti­mized com­po­nents can be designed and man­u­fac­tured with a min­i­mum of mate­r­i­al and the same stiff­ness (com­pared to oth­er mate­ri­als). How­ev­er, the load-bear­ing capac­i­ty of the com­po­nent axi­al­ly off­set from this fiber direc­tion (by about 90°) can­not be achieved to the same extent. In order to be able to intro­duce a minimum
  • In order to be able to intro­duce a min­i­mum of mechan­i­cal shear forces, e.g. pipes, masts, etc. are man­u­fac­tured with more wall thick­ness than com­pa­ra­ble com­po­nents, but they still do not reach the strength of e.g. aluminum.

So avoid the occur­rence of abrupt or high loads due to trans­verse forces, such as the spin­naker pole hit­ting the forestay under load, or apply rein­force­ments to par­tic­u­lar­ly vul­ner­a­ble areas (sheath­ing made of steel, alu­minum or dou­ble-lay­er car­bon tubes) at an ear­ly stage.


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