側溝付き試験片によるJ_<Ic>評価のための有効板厚の実験的一検討(<小特集>信頼性工学小特集)

概要

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Evalution of the elastic-plastic fracture toughness J_<Ic> using side-grooved specimens requires introduction of the so-called effective specimen thickness B_<eff>. At present, three different equations of B<eff> are known. These are B<eff>=√<B_0B_N>, B_<eff>=B_0+(B_0-B_N)^2/B_0 and B_<eff>=B_N, where B_0 is the gross specimen thickness (thickness apart from the side-groove) and B_N is the net specimen thickness (thickness at the bottom of the side-groove). In ASTM Standard Test for j_<Ie>, B<eff>=B_N is used for calculation of J, but its validity does not seem to have been fully confirmed. Thus, this paper examined experimentally which one is appropriate among the above three equations. Experiments were carried out using side-groove compact tension specomens of 2024-T3 Al alloy. The net specimen thickness B_N was chosen so that B_N>25J_<Ic>/σ_<fs> was satisfied. J was calculated using the well-known formula J=(A/Bb)f(a/W). Substituting each of the above three equations of B_<eff> for B, J<Ic> was ted and compared with the value of J<Ic> as obtained from the non-side-grooved specimen. It was found that there exsist a case in which B<eff>=√<B_0B_N>or B_<eff>=B_0-(B_0-B_N)^2/B_0 is more appropriate than B_<eff>=B_N. This result is useful in further investigations of the effective thickness.
社団法人日本材料学会の論文
1987-09-15