In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental...In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental results indicate that both the peak stress and crack initiation stress first decrease and then increase with increasing flaw angle,and they increase linearly with increasing flaw spacing.Moreover,five crack modes occur in these tested samples,including the coplanar secondary cracks,wing cracks,petal cracks,anti-wing cracks,and vertical giant cracks.The growth length of wing cracks is approximately equal to the length of the long axis of preexisting flaw.However,the maximum width is roughly equal to half the length of the long axis of pre-existing elliptic flaw.The final failure modes include the splitting failure induced by wing cracks and vertical giant cracks,and the mixed tensile-shear failure induced by coplanar secondary cracks and wing cracks.展开更多
The recently developed European flaw assessment procedure, structural integrity assessment procedure（SiNTAP） is applied to assessment for welded joints of the API 5L X65 pipeline steel with an assumed embedded flaw ...The recently developed European flaw assessment procedure, structural integrity assessment procedure（SiNTAP） is applied to assessment for welded joints of the API 5L X65 pipeline steel with an assumed embedded flaw and surface flaw at the weld toe. As one of the basic input data, fracture toughness crack tip opening displacement （CTOD） tests are conducted at 0℃ and performed according to the requirements of the standard of BS7448. For the heat affected zone （HAZ） specimens, the microstructure observation is performed to insure that the tip of the crack is located in the coarse grain zone. The result explains the dispersity of the test values. In structural integrity assessment procedure-fracture assessment diagram（SINTAP FAD） method, the failure curves of welded joints at level 1 and 3 are derived from the tensile test results. The results of the assessment show that all assessment points are located within the failure lines of analysis level 1 and 3. So the welded joint of the pipeline is safe. This study laid the foundation of application of SINTAP to pipeline structure assessment.展开更多
基金supported by National Natural Science Foundation of China(Grant Nos.51839009,41807251 and 51679017).
文摘In this paper,the cracking and mechanical responses are studied for the Polymethylmethacrylate(PMMA)sample with two three-dimensional embedded coplanar elliptic flaws subjected to uniaxial compression.The experimental results indicate that both the peak stress and crack initiation stress first decrease and then increase with increasing flaw angle,and they increase linearly with increasing flaw spacing.Moreover,five crack modes occur in these tested samples,including the coplanar secondary cracks,wing cracks,petal cracks,anti-wing cracks,and vertical giant cracks.The growth length of wing cracks is approximately equal to the length of the long axis of preexisting flaw.However,the maximum width is roughly equal to half the length of the long axis of pre-existing elliptic flaw.The final failure modes include the splitting failure induced by wing cracks and vertical giant cracks,and the mixed tensile-shear failure induced by coplanar secondary cracks and wing cracks.
基金This project is supported by National Natural Science Foundation of China(No.50375109).
文摘The recently developed European flaw assessment procedure, structural integrity assessment procedure（SiNTAP） is applied to assessment for welded joints of the API 5L X65 pipeline steel with an assumed embedded flaw and surface flaw at the weld toe. As one of the basic input data, fracture toughness crack tip opening displacement （CTOD） tests are conducted at 0℃ and performed according to the requirements of the standard of BS7448. For the heat affected zone （HAZ） specimens, the microstructure observation is performed to insure that the tip of the crack is located in the coarse grain zone. The result explains the dispersity of the test values. In structural integrity assessment procedure-fracture assessment diagram（SINTAP FAD） method, the failure curves of welded joints at level 1 and 3 are derived from the tensile test results. The results of the assessment show that all assessment points are located within the failure lines of analysis level 1 and 3. So the welded joint of the pipeline is safe. This study laid the foundation of application of SINTAP to pipeline structure assessment.
