可塑剤を含むエポキシ樹脂の疲労き裂伝ぱ

ふん囲気と繰返し速度の影響

抄録

An attempt was made to clarify the effects of atmosphere (vacuum and vapor of benzene) and frequency on fatigue crack propagation of epoxy resins containing plasticizer, whose mechanical properties vary widely with the content of plasticizer involved in the specimen. The properties of fatigue crack growth in the specimen were investigated through the stress intensity factor K, in which the following relations between growth rate and K were assumed. dl/dN=A(K_max)^α₁(ΔK)^α₂ and dl/dN=B(K_mean)^β₁(ΔK)^β₂, where A, α₁, α₂, B, β₁ and β₂ are constants respectively. The effect of frequency was investigated through the factor of (f)^α₃ and (f)^β₃ added to the above equations.
The results obtained are summarized as follows:
(1) The behavior of fatigue crack growth in the specimens in vacuum was similar to that in air.
(2) The values of constants α₁, α₂, β₁ and β₂ obtained from the experiments in vapor of benzene are not so different compared with those in air.
(3) The values of constants A and B obtained from the experiments in vapor of benzene are greater by one order than those in air for the specimens with low plasticizer contents, while they are comparable each other for the specimens with high plasticizer contents.
(4) The values of constants α₃ and β₃ (which are negative) obtained from the experiments on the effect of frequency decrease as the content of plasticizer increases.