FATIGUE BEHAVIOR OF CARBON FIBER REINFORCED UNSATURATED POLYESTER COMPOSITES

Abstract

Hand-lay up method was used to prepare the samples withunsaturated polyester(UPE)as a matnx reinforced with choppedcarbon flbers(CCF).The fatigue behavior of unsaturated polyesterresin/chopped carbon flber composites is studied with different weightpercentage of chopped carbon ibers(2.5%,5%,7.5%,10%,12.5%).Thefatigue test was carrled out under altemate bending method whichmade by applying sinusoidal wave with constant displacement(15 mm)the stress ratio R=-l and loading frequency 10Hz,which is believed togive a negligible temperature rise du五ng the test. The results of themaximuln stress, fatigue strength and fatigue life of the testedcomposites are calculated from stress(S)― number Of cycles(N)(S― N)curves.It was shown that increasing percentage of reinforcement weightincrease the values of maximum stress for all composites, while thevalues of fatigue strength and fatigue life increasing for all compositesexcept the composite with reinforcing weight 12.5%,which suttect torapid failure(fraCture).ThiS failure could be due to the debonding ofthe chopped carbon flbers from the matrlx unsaturated polyester.