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轴向冲击载荷作用下弹性圆柱壳横向弯曲动态屈曲
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作者 马建青 徐新生 +1 位作者 lim c. w. 褚洪杰 《力学学报》 EI CSCD 北大核心 2010年第4期702-709,共8页
研究在轴向冲击载荷下弹性圆柱壳动态屈曲问题.通过构造哈密顿体系,在辛空间中将临界载荷和动态屈曲模态归结为辛本征值和本征解问题.辛本征解反映了局部的压缩屈曲模态和整体的弯曲屈曲模态,特别是在冲击端为自由支承边界时的特殊屈曲... 研究在轴向冲击载荷下弹性圆柱壳动态屈曲问题.通过构造哈密顿体系,在辛空间中将临界载荷和动态屈曲模态归结为辛本征值和本征解问题.辛本征解反映了局部的压缩屈曲模态和整体的弯曲屈曲模态,特别是在冲击端为自由支承边界时的特殊屈曲方式.数值结果给出了具体的临界载荷和屈曲模态规律. 展开更多
关键词 哈密顿体系 圆柱壳 轴向冲击 应力波
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局部表面纳米化双层嵌套式金属薄壁吸能结构的数值模拟和设计
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作者 赵祯 王伟 +5 位作者 廉增博 王钧仡 仝真真 林志华 周震寰 徐新生 《计算力学学报》 EI CAS CSCD 北大核心 2020年第6期770-775,共6页
基于局部表面纳米化技术,设计了一种双层嵌套式金属薄壁吸能结构。在表面纳米化技术对金属力学性能影响的研究基础上,优化了环向交错式和连续式条纹局部表面纳米化布局,得到了双层嵌套式方管吸能结构设计方案和吸能参数。结果表明,表面... 基于局部表面纳米化技术,设计了一种双层嵌套式金属薄壁吸能结构。在表面纳米化技术对金属力学性能影响的研究基础上,优化了环向交错式和连续式条纹局部表面纳米化布局,得到了双层嵌套式方管吸能结构设计方案和吸能参数。结果表明,表面纳米化对材料的屈服极限提升显著,所设计的局部纳米化双层嵌套式方管吸能结构的比吸能可提高57.1%。同时也证实局部表面纳米化是一种有效的吸能提升技术。 展开更多
关键词 双层嵌套式薄壁结构 局部表面纳米化 吸能装置 比吸能 峰值载荷
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Is a nanorod (or nanotube) with a lower Young’s modulus stiffer? Is not Young’s modulus a stiffness indicator? 被引量:5
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作者 lim c. w. 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2010年第4期712-724,共13页
It has been a known fact in classical mechanics of materials that Young’s modulus is an indicator of material stiffness and materials with a higher Young’s modulus are stiffer. At the nanoscale, within the scope and... It has been a known fact in classical mechanics of materials that Young’s modulus is an indicator of material stiffness and materials with a higher Young’s modulus are stiffer. At the nanoscale, within the scope and under specific circumstances described in this paper, however, a nanorod (or a nanotube) with a smaller Young’s modulus (smaller stress-strain rate) is stiffer. In such a scenario, Young’s modulus is not a stiffness indicator for nanostructures. Furthermore, the nonlocal stress-strain rate is dependent on types of load, boundary conditions and location. This is likely to be one of the many possible reasons why numerous experiments in the past obtained significantly varying values of Young’s modulus for a seemingly identical nanotube, i.e. because the types of loading and/or boundary conditions in the experiments were different, as well as at which point the property was measured. Based on the nonlocal elasticity theory and within the scope of material and geometric linearity, this paper reports the strange and hitherto unrealized effect that a nanorod (or a nanotube) with a lower Young’s modulus (smaller stress-strain rate) indicates smaller extension in tensile analysis. Similarly, it is also predicted that a nanorod (or a nanotube) with a lower Young’s modulus results in smaller bending deflection, higher critical buckling load, higher free vibration frequency and higher wave propagation velocity, which are at all consequences of a stiffer nanostructure. 展开更多
关键词 nanorod NANOTUBE NONLOCAL stress NONLOCAL ELASTICITY STIFFNESS tensile Young’s MODULUS
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Transverse vibration of pre-tensioned nonlocal nanobeams with precise internal axial loads 被引量:2
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作者 LI cheng lim c. w. +1 位作者 YU JiLin ZENG Qingchuan 《Science China(Technological Sciences)》 SCIE EI CAS 2011年第8期2007-2013,共7页
This paper investigates the transverse vibration of a simply supported nanobeam with an initial axial tension based on the nonlocal stress field theory with a nonlocal size parameter. Considering an axial elongation d... This paper investigates the transverse vibration of a simply supported nanobeam with an initial axial tension based on the nonlocal stress field theory with a nonlocal size parameter. Considering an axial elongation due to transverse vibration, the internal axial tension is not precisely equal to the external initial tension. A sixth-order nonlinear partial differential equation that governs the transverse vibration for such nonlocal nanobeam is derived. Using a perturbation method, the relation between natural frequency and nonlocal nanoscale parameter is derived and the transverse vibration mode is solved. The external axial tension and nonlocal nanoscale parameter are proven to play significant roles in the nonlinear vibration behavior of nonlocal nanobeams. Such effects enhance the natural frequency and stiffness as compared to the predictions of the classical continuum mechanics models. Additionally, the frequency is higher if the precise internal axial load is considered with respect to that when only the approximate internal axial tension is assumed. 展开更多
关键词 nonlocal stress natural frequency free vibration nonlocal nanoscale
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