Hydrogen diffusion coefficients of different regions in the welded joint of X80 pipeline steel were measured using the electro-chemical permeation technique. Using ABAQUS software, hydrogen diffusion in X80 pipeline s...Hydrogen diffusion coefficients of different regions in the welded joint of X80 pipeline steel were measured using the electro-chemical permeation technique. Using ABAQUS software, hydrogen diffusion in X80 pipeline steel welded joint was studied in consideration of the inhomogeneity of the welding zone, and temperature-dependent thermo-physical and mechanical properties of the metals. A three dimensional finite element model was developed and a coupled thermo-mechanical-diffusion analysis was performed. Hydrogen concentration distribution across the welded joint was obtained. It is found that the postweld residual hydrogen exhibits a non-uniform distribution across the welded joint. A maximum equivalent stress occurs in the immediate vicinity of the weld metal. The heat affected zone has the highest hydrogen concentration level, followed by the weld zone and the base metal.Simulation results are well consistent with theoretical analysis.展开更多
Objective： To create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament （LCL） with or without displaced movements at different knee flexion condi...Objective： To create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament （LCL） with or without displaced movements at different knee flexion conditions. Methods： A four-major-ligament contained knee specimen from an adult died of skull injury was prepared for CT scanning with the detectable ligament insertion footprints, locations and orientations precisely marked in advance. The CT scanning images were converted to a 3-dimensional model of the knee with the 3-dimensional reconstruction technique and transformed into finite element model by the software of ANSYS. The model was validated using experimental and numerical results obtained by other scientists. The natural stress changes of LCL at five different knee flexion angles （0°, 30°60°, 90°, 120°） and under various motions of anterior-posterior tibial translation, tibial varus rotation and internal-external tibial rotation were measured. Results： The maximum stress reached to 87%-113% versus natural stress in varus motion at early 30° of knee flexions. The stress values were smaller than the peak value of natural stress at 0° （knee full extension） when knee bending was over 60° of flexion in anterior-posterior tibial translation and internal-external rotation. Conclusion： LCL is vulnerable to varus motion in almost all knee bending positions and susceptible to ante- rior-posterior tibial translation or internal-external rotation at early 30° of knee flexions.展开更多
In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible f...In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible future directions of the current simulation frameworks. In particular, the model inspects the crossover between the disciplines of modeling and simulation, service-orientation,and software/systems engineering. Finally, two specific simulation frameworks are studied as examples.展开更多
基金Project(BK2011258)supported by the Natural Science Foundation of Jiangsu Province,China
文摘Hydrogen diffusion coefficients of different regions in the welded joint of X80 pipeline steel were measured using the electro-chemical permeation technique. Using ABAQUS software, hydrogen diffusion in X80 pipeline steel welded joint was studied in consideration of the inhomogeneity of the welding zone, and temperature-dependent thermo-physical and mechanical properties of the metals. A three dimensional finite element model was developed and a coupled thermo-mechanical-diffusion analysis was performed. Hydrogen concentration distribution across the welded joint was obtained. It is found that the postweld residual hydrogen exhibits a non-uniform distribution across the welded joint. A maximum equivalent stress occurs in the immediate vicinity of the weld metal. The heat affected zone has the highest hydrogen concentration level, followed by the weld zone and the base metal.Simulation results are well consistent with theoretical analysis.
文摘Objective： To create a 3-dimensional finite element model of knee ligaments and to analyse the stress changes of lateral collateral ligament （LCL） with or without displaced movements at different knee flexion conditions. Methods： A four-major-ligament contained knee specimen from an adult died of skull injury was prepared for CT scanning with the detectable ligament insertion footprints, locations and orientations precisely marked in advance. The CT scanning images were converted to a 3-dimensional model of the knee with the 3-dimensional reconstruction technique and transformed into finite element model by the software of ANSYS. The model was validated using experimental and numerical results obtained by other scientists. The natural stress changes of LCL at five different knee flexion angles （0°, 30°60°, 90°, 120°） and under various motions of anterior-posterior tibial translation, tibial varus rotation and internal-external tibial rotation were measured. Results： The maximum stress reached to 87%-113% versus natural stress in varus motion at early 30° of knee flexions. The stress values were smaller than the peak value of natural stress at 0° （knee full extension） when knee bending was over 60° of flexion in anterior-posterior tibial translation and internal-external rotation. Conclusion： LCL is vulnerable to varus motion in almost all knee bending positions and susceptible to ante- rior-posterior tibial translation or internal-external rotation at early 30° of knee flexions.
基金Project (Nos.60574056 and 60674069) supported by the National Natural Science Foundation of China
文摘In this letter,we propose a novel three-dimensional conceptual model for an emerging service-oriented simulation paradigm. The model can be used as a guideline or an analytic means to find the potential and possible future directions of the current simulation frameworks. In particular, the model inspects the crossover between the disciplines of modeling and simulation, service-orientation,and software/systems engineering. Finally, two specific simulation frameworks are studied as examples.
