Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applica...Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applications. It has been successfully applied in the study of crystal plasticity/brittle fracture process and decohesion between delaminations. In this paper, tensile experiments of large steel plate with different length of pre-existing cracks are conducted. Based on commercial software ABAQUS, cohesive element is adopted to simulate the tensile tests, and appropriate parameter values are obtained by fitting displacement-force curves. Using these parameters, a numerical method is presented by applying cohesive element to thermo-elastic-plastic finite element method （TEP-FEM） to simulate plate rigid restraint cracking （PRRC） tests. By changing constitutive relation of cohesive element, dimensions of the model and welding conditions, the influence of welding restraint intensity and welding conditions on the crack propagation are discussed, respectively. Three types of welding cold cracking are simulated. Significant influence of welding cold cracking on resistant stress in welding line is captured by this numerical method.展开更多
Aim： To determine the effect of sildenafil citrate on the nocturnal penile erections （i.e. time to onset, the duration of erection, and the interval between first and second erections） of healthy young men. Methods...Aim： To determine the effect of sildenafil citrate on the nocturnal penile erections （i.e. time to onset, the duration of erection, and the interval between first and second erections） of healthy young men. Methods： Twenty-two potent men, 23-29 years old, were recruited for the study. All subjects completed three sessions over consecutive nights using the RigiScan monitoring device （Dacomed, Minneapolis, USA）. After a first night of adaptation, night 2 records were their baseline values, and on night 3 they received 100 mg of sildenafil citrate. Statistical comparisons were done between the second and third night data. Results： The mean time to onset of the first erection with sildenafil citrate was （34 ± 18） min, whereas it was （74 ± 24） min （P 〈 0.001） without sildenafil citrate. The number of erections observed during the first 5 h after sildenafil citrate medication was 3.6 ± 0.5 in contrast to 2.4 ± 0.5 with no medica- tion （P = 0.001）. The interval between first and second erections was shorter with sildenafil citrate： （52 ± 26） min vs. （85 ± 34） min （P = 0.01）. The duration of the last erection was statistically significantly longer with the sildenafil citrate： （64 ± 33） min vs. （42 ± 28） min （P 〈 0.01）. Conclusion： Healthy young men achieved erection within 34 min after sildenafil citrate administration, which is shorter than the 1 h interval proposed by the manufacturer. The interval between the first and second erections was shorter and the duration of the last nocturnal erection was longer.展开更多
文摘Cohesive element is developed from the Dugdal-Barenblatt model in the field of fracture mechanics. The mechanical constitutive relation of cohesive element can be artificially assumed depending on the specific applications. It has been successfully applied in the study of crystal plasticity/brittle fracture process and decohesion between delaminations. In this paper, tensile experiments of large steel plate with different length of pre-existing cracks are conducted. Based on commercial software ABAQUS, cohesive element is adopted to simulate the tensile tests, and appropriate parameter values are obtained by fitting displacement-force curves. Using these parameters, a numerical method is presented by applying cohesive element to thermo-elastic-plastic finite element method （TEP-FEM） to simulate plate rigid restraint cracking （PRRC） tests. By changing constitutive relation of cohesive element, dimensions of the model and welding conditions, the influence of welding restraint intensity and welding conditions on the crack propagation are discussed, respectively. Three types of welding cold cracking are simulated. Significant influence of welding cold cracking on resistant stress in welding line is captured by this numerical method.
文摘Aim： To determine the effect of sildenafil citrate on the nocturnal penile erections （i.e. time to onset, the duration of erection, and the interval between first and second erections） of healthy young men. Methods： Twenty-two potent men, 23-29 years old, were recruited for the study. All subjects completed three sessions over consecutive nights using the RigiScan monitoring device （Dacomed, Minneapolis, USA）. After a first night of adaptation, night 2 records were their baseline values, and on night 3 they received 100 mg of sildenafil citrate. Statistical comparisons were done between the second and third night data. Results： The mean time to onset of the first erection with sildenafil citrate was （34 ± 18） min, whereas it was （74 ± 24） min （P 〈 0.001） without sildenafil citrate. The number of erections observed during the first 5 h after sildenafil citrate medication was 3.6 ± 0.5 in contrast to 2.4 ± 0.5 with no medica- tion （P = 0.001）. The interval between first and second erections was shorter with sildenafil citrate： （52 ± 26） min vs. （85 ± 34） min （P = 0.01）. The duration of the last erection was statistically significantly longer with the sildenafil citrate： （64 ± 33） min vs. （42 ± 28） min （P 〈 0.01）. Conclusion： Healthy young men achieved erection within 34 min after sildenafil citrate administration, which is shorter than the 1 h interval proposed by the manufacturer. The interval between the first and second erections was shorter and the duration of the last nocturnal erection was longer.
