Landslides are one of the key problems for stability analysis of pipelines in the western region of China where the geological conditions are extremely complicated. In order to offer a theoretical basis for the pipe-s...Landslides are one of the key problems for stability analysis of pipelines in the western region of China where the geological conditions are extremely complicated. In order to offer a theoretical basis for the pipe-soil interaction, the general finite element program ABAQUS is used to analyze the distribution of pipe strain caused by landslide through which the pipeline passes. In this paper the Ramberg-Osgood constitutive equation is used to study the strain-based mechanical characteristics of pipelines. Different calculation schemas are designed by considering the change of spatial relationship between pipeline and landslide, and the change of D/t, diameter-thickness ratio of pipeline. The results indicate that the pipeline is primarily subjected to tension stress when the landslide crosses the pipeline perpendicularly, the pipe strain is a maximum along the central axis of the landslide, and reverse bending occurs on pipeline at both edges of the landslide. The pipeline is primarily subjected to friction force caused by the downward movement of the landslide, and the friction force is relatively small when the landslide is parallel to the pipeline. The pipe strain is in proportional to D/t, and this means decreasing D/t can help to improve security of pipelines subjected to the landslide.展开更多
Sensitivity analysis and topology optimization of microstructures using strain energy-based method is presented. Compared with homogenization method, the strain energy-based method has advantages of higher computing e...Sensitivity analysis and topology optimization of microstructures using strain energy-based method is presented. Compared with homogenization method, the strain energy-based method has advantages of higher computing efficiency and simplified programming. Both the dual convex programming method and perimeter constraint scheme are used to optimize the 2D and 3D microstructures. Numerical results indicate that the strain energy-based method has the same effectiveness as that of homogenization method for orthotropic materials.展开更多
针对爆炸容器初始设计常用的动力系数法存在的设计余量过大问题,通过将Johnson-Cook本构模型的应变率项纳入结构振动方程,推导出考虑应变率效应的等效静载荷计算方法。采用本文方法及常规动力系数法对不同半径的球形容器在1 kg TNT炸药...针对爆炸容器初始设计常用的动力系数法存在的设计余量过大问题,通过将Johnson-Cook本构模型的应变率项纳入结构振动方程,推导出考虑应变率效应的等效静载荷计算方法。采用本文方法及常规动力系数法对不同半径的球形容器在1 kg TNT炸药加载下的壁厚进行了理论设计,并通过高置信度数值模型对两种方法所设计的容器的结构响应进行了数值计算。结果显示,两种方法所设计的容器均在弹性范围,但是本文方法的容器壁厚更小、结构应力更大。这表明通过考虑应变率效应,本文方法可合理降低设计载荷以减小设计余量,进而更充分地发挥材料与结构的力学性能,并可用于金属爆炸容器的初始设计。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 50774090)
文摘Landslides are one of the key problems for stability analysis of pipelines in the western region of China where the geological conditions are extremely complicated. In order to offer a theoretical basis for the pipe-soil interaction, the general finite element program ABAQUS is used to analyze the distribution of pipe strain caused by landslide through which the pipeline passes. In this paper the Ramberg-Osgood constitutive equation is used to study the strain-based mechanical characteristics of pipelines. Different calculation schemas are designed by considering the change of spatial relationship between pipeline and landslide, and the change of D/t, diameter-thickness ratio of pipeline. The results indicate that the pipeline is primarily subjected to tension stress when the landslide crosses the pipeline perpendicularly, the pipe strain is a maximum along the central axis of the landslide, and reverse bending occurs on pipeline at both edges of the landslide. The pipeline is primarily subjected to friction force caused by the downward movement of the landslide, and the friction force is relatively small when the landslide is parallel to the pipeline. The pipe strain is in proportional to D/t, and this means decreasing D/t can help to improve security of pipelines subjected to the landslide.
基金National Natural Science Foundation of China （90405016, 10676028） 973 Program （2006CB601205）+1 种基金 863 Project （2006AA04Z 122） Aeronautical Science Foundation （04B53080, 2006ZA 53006） and 111 Project （B07050）
文摘Sensitivity analysis and topology optimization of microstructures using strain energy-based method is presented. Compared with homogenization method, the strain energy-based method has advantages of higher computing efficiency and simplified programming. Both the dual convex programming method and perimeter constraint scheme are used to optimize the 2D and 3D microstructures. Numerical results indicate that the strain energy-based method has the same effectiveness as that of homogenization method for orthotropic materials.
文摘针对爆炸容器初始设计常用的动力系数法存在的设计余量过大问题,通过将Johnson-Cook本构模型的应变率项纳入结构振动方程,推导出考虑应变率效应的等效静载荷计算方法。采用本文方法及常规动力系数法对不同半径的球形容器在1 kg TNT炸药加载下的壁厚进行了理论设计,并通过高置信度数值模型对两种方法所设计的容器的结构响应进行了数值计算。结果显示,两种方法所设计的容器均在弹性范围,但是本文方法的容器壁厚更小、结构应力更大。这表明通过考虑应变率效应,本文方法可合理降低设计载荷以减小设计余量,进而更充分地发挥材料与结构的力学性能,并可用于金属爆炸容器的初始设计。
