In this research, vibration and wave propagation analysis of a twisted micro- beam on Pasternak foundation is investigated. The strain-displacement relations （kine-matic equations） are calculated by the displacement...In this research, vibration and wave propagation analysis of a twisted micro- beam on Pasternak foundation is investigated. The strain-displacement relations （kine-matic equations） are calculated by the displacement fields of the twisted micro-beam. The strain gradient theory （SGT） is used to implement the size dependent effect at micro-scale. Finally, using an energy method and Hamilton＇s principle, the governing equations of motion for the twisted micro-beam are derived. Natural frequencies and the wave prop- agation speed of the twisted micro-beam are calculated with an analytical method. Also, the natural frequency, the phase speed, the cut-off frequency, and the wave number of the twisted micro-beam are obtained by considering three material length scale parameters, the rate of twist angle, the thickness, the length of twisted micro-beam, and the elastic medium. The results of this work indicate that the phase speed in a twisted micro-beam increases with an increase in the rate of twist angle. Moreover, the wave number is in- versely related with the thickness of micro-beam. Meanwhile, it is directly related to the wave propagation frequency. Increasing the rate of twist angle causes the increase in the natural frequency especially with higher thickness. The effect of the twist angle rate on the group velocity is observed at a lower wave propagation frequency.展开更多
本文应用Flexible Atom Code(FAC)程序用3种不同的计算方法——相对论扭曲波(DW)理论、Conlomb-Born-Exchange(CBE)近似理论、Binary-Encounter-Diaole(BED)理论,计算了类氖离子Se24+的电子碰撞截面和组态能量。不仅计算了基态1s22s22p6...本文应用Flexible Atom Code(FAC)程序用3种不同的计算方法——相对论扭曲波(DW)理论、Conlomb-Born-Exchange(CBE)近似理论、Binary-Encounter-Diaole(BED)理论,计算了类氖离子Se24+的电子碰撞截面和组态能量。不仅计算了基态1s22s22p6(1S)和激发态1s22s22p5(2P)、1s22s12p6(2S)的组态能量,而且计算了离子的电子碰撞离化截面(EII),包括三条途径:1s22s22p6(1S)→1s22s22p5(2P3/2);1s22s22p6(1S)→1s22s22p5(2P1/2);1s22s22p6(1S)→1s22s12p6(2S)。展开更多
基金Project supported by the Iranian Nanotechnology Development Committee and the University of Kashan(No.463855/11)
文摘In this research, vibration and wave propagation analysis of a twisted micro- beam on Pasternak foundation is investigated. The strain-displacement relations （kine-matic equations） are calculated by the displacement fields of the twisted micro-beam. The strain gradient theory （SGT） is used to implement the size dependent effect at micro-scale. Finally, using an energy method and Hamilton＇s principle, the governing equations of motion for the twisted micro-beam are derived. Natural frequencies and the wave prop- agation speed of the twisted micro-beam are calculated with an analytical method. Also, the natural frequency, the phase speed, the cut-off frequency, and the wave number of the twisted micro-beam are obtained by considering three material length scale parameters, the rate of twist angle, the thickness, the length of twisted micro-beam, and the elastic medium. The results of this work indicate that the phase speed in a twisted micro-beam increases with an increase in the rate of twist angle. Moreover, the wave number is in- versely related with the thickness of micro-beam. Meanwhile, it is directly related to the wave propagation frequency. Increasing the rate of twist angle causes the increase in the natural frequency especially with higher thickness. The effect of the twist angle rate on the group velocity is observed at a lower wave propagation frequency.
文摘本文应用Flexible Atom Code(FAC)程序用3种不同的计算方法——相对论扭曲波(DW)理论、Conlomb-Born-Exchange(CBE)近似理论、Binary-Encounter-Diaole(BED)理论,计算了类氖离子Se24+的电子碰撞截面和组态能量。不仅计算了基态1s22s22p6(1S)和激发态1s22s22p5(2P)、1s22s12p6(2S)的组态能量,而且计算了离子的电子碰撞离化截面(EII),包括三条途径:1s22s22p6(1S)→1s22s22p5(2P3/2);1s22s22p6(1S)→1s22s22p5(2P1/2);1s22s22p6(1S)→1s22s12p6(2S)。
