115 Numerical Study of Asperity Effect on the Crack Closure Behavior

概要

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The load-crack mouth opening displacement (CMOD) relations in a CT specimen was numerically studied with and without the artificial asperity/wedge. The asperity was found to have a significant effect on the trend of the load-CMOD curves. The lower portion of the load-CMOD curves in the unloading phase exhibited a linear relation without the asperity, while a concave shape with the wedge. The concave shape, signifying the acceleration in the CMOD decrease, was similarly observed in that obtained experimentally. The concave shape was attributed to the elastic and plastic deformation in the wedge and specimen arising from the contact action. Based on their deformation observations, a crack closure process model was proposed, where three major stages of the unloading curve was defined: (i) the asperity does not contact the upper crack surface, (ii) a process where both the asperity and the specimen material deform elastically, and (iii) the plastic deformation in the specimen material adjacent to the asperity occurs, thus resulting in the concavely shaped load-CMOD curves.
社団法人日本機械学会の論文
2006-09-30