Wave propagation analysis for a functionally graded nanobeam with rectangular cross-section resting on visco-Pasternak＇s foundation is studied in this paper. Timoshenko＇s beam model and nonlocal elasticity theory ar...Wave propagation analysis for a functionally graded nanobeam with rectangular cross-section resting on visco-Pasternak＇s foundation is studied in this paper. Timoshenko＇s beam model and nonlocal elasticity theory are employed for formulation of the problem. The equations of motion are derived using Hamilton＇s principals by calculating kinetic energy, strain energy and work due to viscoelastic foundation. The effects of various parameters such as wavenumber, non-homogeneous index, nonlocal parameter and three parameters of foundation are performed on the phase velocity of the nanobeam. The obtained results indicate that some parameters such as non-homogeneous index, nonlocal parameter and wavenumber have significant effect on the response of the system.展开更多
断层错动诱发上覆土体破坏对跨越断层的埋地管道结构安全构成巨大威胁,是复杂环境地下管线设计中不可忽略的场地因素。既有成果较少涉及正断层和逆断层错动影响下的解析解分析,且针对断层-管道相互作用的理论研究一般将管道结构视为连...断层错动诱发上覆土体破坏对跨越断层的埋地管道结构安全构成巨大威胁,是复杂环境地下管线设计中不可忽略的场地因素。既有成果较少涉及正断层和逆断层错动影响下的解析解分析,且针对断层-管道相互作用的理论研究一般将管道结构视为连续管道,较少考虑管道接口的影响。首先,在简化SSR(静止区stationaryzone,剪切区shearingzone,刚体区rigid body zone)土体变形模型的基础上,结合erf函数和erfc函数,得到了正断层和逆断层错动影响下的土体位移曲线;其次,引入双参数Pasternak地基模型,对管道微元进行受力分析,借助有限差分法求解得到埋地管道结构的变形和内力;最后,将理论解析解和已有的试验结果及数值模拟结果进行对比验证,获得了较好的一致性。此外,针对断层倾角、断层与管道交点位置和接口转动刚度等关键物理特征参数进行了敏感性分析。结果表明:断层倾角会改变管道位移曲线和轴向应力曲线位置,但其位移最大值和轴向应力最大值基本一致,而断层与管道交点位置不仅会改变管道位移曲线和轴向应力曲线形状,其轴向应力最大值也将发生改变;随着接口转动刚度增大,管道最大轴向应力值随之增大,当接口转动刚度足够大时,可将非连续管道视作连续管道进行计算。展开更多
基金financially supported by the University of Kashan(Grant Number:363460/5)Iranian Nanotechnology Development Committee(Grant Number:1396/17)
文摘Wave propagation analysis for a functionally graded nanobeam with rectangular cross-section resting on visco-Pasternak＇s foundation is studied in this paper. Timoshenko＇s beam model and nonlocal elasticity theory are employed for formulation of the problem. The equations of motion are derived using Hamilton＇s principals by calculating kinetic energy, strain energy and work due to viscoelastic foundation. The effects of various parameters such as wavenumber, non-homogeneous index, nonlocal parameter and three parameters of foundation are performed on the phase velocity of the nanobeam. The obtained results indicate that some parameters such as non-homogeneous index, nonlocal parameter and wavenumber have significant effect on the response of the system.
文摘断层错动诱发上覆土体破坏对跨越断层的埋地管道结构安全构成巨大威胁,是复杂环境地下管线设计中不可忽略的场地因素。既有成果较少涉及正断层和逆断层错动影响下的解析解分析,且针对断层-管道相互作用的理论研究一般将管道结构视为连续管道,较少考虑管道接口的影响。首先,在简化SSR(静止区stationaryzone,剪切区shearingzone,刚体区rigid body zone)土体变形模型的基础上,结合erf函数和erfc函数,得到了正断层和逆断层错动影响下的土体位移曲线;其次,引入双参数Pasternak地基模型,对管道微元进行受力分析,借助有限差分法求解得到埋地管道结构的变形和内力;最后,将理论解析解和已有的试验结果及数值模拟结果进行对比验证,获得了较好的一致性。此外,针对断层倾角、断层与管道交点位置和接口转动刚度等关键物理特征参数进行了敏感性分析。结果表明:断层倾角会改变管道位移曲线和轴向应力曲线位置,但其位移最大值和轴向应力最大值基本一致,而断层与管道交点位置不仅会改变管道位移曲线和轴向应力曲线形状,其轴向应力最大值也将发生改变;随着接口转动刚度增大,管道最大轴向应力值随之增大,当接口转动刚度足够大时,可将非连续管道视作连续管道进行计算。
