In this context,four specimens,i.e.(i)circumferentially notched cylindrical torsion(CNCT),(ii)circum-ferentially notched cylindrical direct tension(CNCDT),(iii)edge notch disc bend(ENDB)and(iv)three-point bend beam(3P...In this context,four specimens,i.e.(i)circumferentially notched cylindrical torsion(CNCT),(ii)circum-ferentially notched cylindrical direct tension(CNCDT),(iii)edge notch disc bend(ENDB)and(iv)three-point bend beam(3PBB),were utilized to measure the modesⅠandⅢfracture toughness values of gypsum.While the CNCT specimen provides pure modeⅢloading in a direct manner,this pure mode condition is indirectly produced by the ENDB specimen.The ENDB specimen provided lower KⅢc and a non-coplanar(i.e.twisted)fracture surface compared with the CNCT specimen,which showed a planar modeⅢfracture surface.The ENDB specimen is also employed for conducting pure modeⅠ(with different crack depths)and mixed modeⅠ/Ⅲtests.KIc value was independent of the notch depth,and it was consistent with the RILEM and ASTM standard methods.But the modeⅢfracture results were highly sensitive to the notch depth.While the fracture resistance against modeⅢwas significantly lower than that of modeⅠ,the greater work of fracture under modeⅢwas noticeable.展开更多
A closed-form solution for predicting the tangential stress of an inclusion locatedin mixed mode I and II crack tip field was developed based on the Eshelby equivalent inclusiontheory. Then a mixed mode fracture crite...A closed-form solution for predicting the tangential stress of an inclusion locatedin mixed mode I and II crack tip field was developed based on the Eshelby equivalent inclusiontheory. Then a mixed mode fracture criterion, including the fracture direction and the criticalload, was established based on the maximum tangential stress in the inclusion for brittle inclusion-induced fracture materials. The proposed fracture criterion is a function of the inclusion fracturestress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrixmaterial. The present criterion will reduce to the conventional one as the inclusion having thesame elastic behavior as the matrix material. The proposed solutions are in good agreement withdetailed finite element analysis and measurement.展开更多
文摘In this context,four specimens,i.e.(i)circumferentially notched cylindrical torsion(CNCT),(ii)circum-ferentially notched cylindrical direct tension(CNCDT),(iii)edge notch disc bend(ENDB)and(iv)three-point bend beam(3PBB),were utilized to measure the modesⅠandⅢfracture toughness values of gypsum.While the CNCT specimen provides pure modeⅢloading in a direct manner,this pure mode condition is indirectly produced by the ENDB specimen.The ENDB specimen provided lower KⅢc and a non-coplanar(i.e.twisted)fracture surface compared with the CNCT specimen,which showed a planar modeⅢfracture surface.The ENDB specimen is also employed for conducting pure modeⅠ(with different crack depths)and mixed modeⅠ/Ⅲtests.KIc value was independent of the notch depth,and it was consistent with the RILEM and ASTM standard methods.But the modeⅢfracture results were highly sensitive to the notch depth.While the fracture resistance against modeⅢwas significantly lower than that of modeⅠ,the greater work of fracture under modeⅢwas noticeable.
基金Project supported by the National Basic Research Program of China (No. 2004CB619303).
文摘A closed-form solution for predicting the tangential stress of an inclusion locatedin mixed mode I and II crack tip field was developed based on the Eshelby equivalent inclusiontheory. Then a mixed mode fracture criterion, including the fracture direction and the criticalload, was established based on the maximum tangential stress in the inclusion for brittle inclusion-induced fracture materials. The proposed fracture criterion is a function of the inclusion fracturestress, its size and volume fraction, as well as the elastic constants of the inclusion and the matrixmaterial. The present criterion will reduce to the conventional one as the inclusion having thesame elastic behavior as the matrix material. The proposed solutions are in good agreement withdetailed finite element analysis and measurement.
