Accurate determination of crack opening stress is of central importance to fatigue crack growth analysis and life prediction based on the crack-closure model. This paper studies the crack opening behavior for center- ...Accurate determination of crack opening stress is of central importance to fatigue crack growth analysis and life prediction based on the crack-closure model. This paper studies the crack opening behavior for center- and edge-crack tension specimens. It is found that the crack opening stress is affected by the crack tip element. By taking the crack tip element into account, a modified crack opening stress equation is given for the center-crack tension specimen. Crack surface displace- ment equations for an edge crack in a semi-infinite plate under remote uniform tension and partially distributed pressure are derived by using the weight function method. Based on these displacements, a crack opening stress equation for an edge crack in a semi-infinite plate under uniform tension has been developed. The study shows that the crack opening stress is geometry-dependent, and the weight function method provides an effective and reliable tool to deal with such geometry depen- dence.展开更多
Acid-controlled,chemodivergent and redox-neutral annulations for the synthesis of isocoumarins and isoquinolinones have been realized via Rh(Ⅲ)-cataIyzed C—H activation.Diazo compounds act as a carbene precursor,and...Acid-controlled,chemodivergent and redox-neutral annulations for the synthesis of isocoumarins and isoquinolinones have been realized via Rh(Ⅲ)-cataIyzed C—H activation.Diazo compounds act as a carbene precursor,and coupling occurs in one-pot process,where adipic acid and trimethylacetic acid promote chemodivergent cyclizations.展开更多
When the title compound was treated in protic solvent with alkali catalyses,γ-lacatam was almost the sole product.The ratio of ketone 1 to ketone 2 depended upon the reaction condition.
文摘Accurate determination of crack opening stress is of central importance to fatigue crack growth analysis and life prediction based on the crack-closure model. This paper studies the crack opening behavior for center- and edge-crack tension specimens. It is found that the crack opening stress is affected by the crack tip element. By taking the crack tip element into account, a modified crack opening stress equation is given for the center-crack tension specimen. Crack surface displace- ment equations for an edge crack in a semi-infinite plate under remote uniform tension and partially distributed pressure are derived by using the weight function method. Based on these displacements, a crack opening stress equation for an edge crack in a semi-infinite plate under uniform tension has been developed. The study shows that the crack opening stress is geometry-dependent, and the weight function method provides an effective and reliable tool to deal with such geometry depen- dence.
文摘Acid-controlled,chemodivergent and redox-neutral annulations for the synthesis of isocoumarins and isoquinolinones have been realized via Rh(Ⅲ)-cataIyzed C—H activation.Diazo compounds act as a carbene precursor,and coupling occurs in one-pot process,where adipic acid and trimethylacetic acid promote chemodivergent cyclizations.
文摘When the title compound was treated in protic solvent with alkali catalyses,γ-lacatam was almost the sole product.The ratio of ketone 1 to ketone 2 depended upon the reaction condition.
