非线性滞弹性—一门新的学科领域

固体的力学性质包括弹性、范性和断裂，由于实际应用上的重要性，关于断裂的研究已经受到相当重视，但是范性形变是断裂过程的前奏，因此在解决固体材料破坏问题的整个环节中，必须研究范性形变的机制。另一方面，弹性形态是范性形变的先导，而目前作为阐明范性形变要制的基础的位错理论还不能与研究弹性形变的弹性理论衔接起来，所以需要重视从弹性到范性的过渡的研究。该文介绍的非线性滞弹性是关于这方面的一种初步尝试。     

Franck-Hertz实验曲线的统计解释

用电子数按能量的分布解释Ｆ－Ｈ实验曲线极大值和极小值的形成原因     

关于岩石三阶弹性常数的超声测量方法

油气储层岩石的三阶弹性常数反映了该岩石的速度应力敏感性,是利用声波测井或地震资料进行原位地应力反演的基本参数。本文阐述了利用声弹性理论在实验室测量岩石三阶弹性常数的原理与方法,并给出了部分实验结果。这些参数将为研究声波在预应力声场中传播规律的提供基础数据,同时也为定量分析利用交叉偶极声波测井评价地应力的精度提供了依据。不同岩石的三阶弹性常数较大差异表明,通过速度各向异性进行应力反演时必须考虑岩石本身非线性的差异。     

Local resonant characteristics of a layered cylinder embedded in the elastic medium

Three kinds of resonant modes of a single layered circular elastic cylinder embedded in the elastic medium are analysed by considering the oscillation of the scatter＇s core, based on the fact that the core moves as a rigid body when the shell material is very compliant. The resonant frequencies of the single resonator acquired by our method are in good agreement with those calculated by the local interaction simulation approach （LISA） for the local resonant phononic crystal. Therefore, the local resonant characteristics of a single layered circular elastic cylinder can be used to evaluate the resonant frequencies of the phononic crystal. The effects of the geometrical and physical parameters of the shell and the core are also studied in details. This work is significant for designing the locally resonant phononic crystal based on the local resonant characteristics of the single resonator, and the resonant frequencies can be tuned by selecting the geometrical sizes and the materials.     

稀土硼化物LaB6晶体材料的弹性性质和力学性能

利用密度泛函理论和Birch-Murnaghan物态方程,系统分析了LaB6晶体材料的弹性常数参数、体弹性模量、剪切弹性模量及其他力学性能。结果表明:LaB6晶体具有较大的弹性常数参数C11,说明在此主轴应力方向上具有较大的弹性常数;同时它还具有较大的体弹性模量,并且体弹性模量具有各向同性,剪切弹性模量具有各向异性;LaB6晶体的杨氏模量为227.85 GPa,泊松比为0.26,体剪弹性模量比值达到1.44,表明其脆性较强,不易发生弹性形变;LaB6晶体的硬度达到11.56 GPa,平均弹性波速达4.87 km/s。LaB6的带隙宽度为0.20 eV,呈金属性,内部电子具有较强的局域性,La和B之间具有较强的共价键成分。     

小球与均质定轴杆的碰撞(续)

从碰撞过程中形变与能量的转换关系出发,采用弹性度的概念,提供了解决小球与定轴杆一般非弹性碰撞问题的一种解法.     

高能电子弹性和非弹性散射的动力学理论—多片层法

本文综述了弹性多片层理论在反射电子显微镜中的应用。根据实验事实,提出了弹性理论的局限性。进而从量子力学推导出描述高能电子非弹性散射的新多片层理论,并把它应用到计算电子与等离激元和固体声子相互作用的非弹性过程中。该理论可以用来模拟非弹性电子所成的高分辨原子场。     

基于双带宽高斯滤波器的磁共振弹性图局域频率估算算法研究与实现

本文对生物体软组织的生物力学模型进行了分析推导和简化,得到了磁共振相位图与生物组织弹性之间的力学关系,根据该关系研究了局域频率估算算法,应用Matlab对算法进行了编程实现,体模弹性图的实现验证了算法有效性,为后续开展临床肝纤维化分级研究奠定基础. 关键词： 磁共振弹性成像 弹性生物力学模型 局域频率估算     

Group-theoretical method for physical property tensors of quasicrystals

In addition to the phonon variable there is the phason variable in hydrodynamics for quasicrystals. These two kinds of hydrodynamic variables have different transformation properties. The phonon variable transforms under the vector representation, whereas the phason variable transforms under another related representation. Thus, a basis (or a set of basis functions) in the representation space should include such two kinds of variables. This makes it more difficult to determine the physical property tensors of quasicrystals. In this paper the group-theoretical method is given to determine the physical property tensors of quasicrystals. As an illustration of this method we calculate the third-order elasticity tensors of quasicrystals with five-fold symmetry by means of basis functions. It follows that the linear phonon elasticity is isotropic, but the nonlinear phonon elasticity is anisotropic for pentagonal quasicrystals. Meanwhile, the basis functions are constructed for all noncrystallographic point groups of quasicrystals.     

Correlation of Two Coupled Particles in Viscoelastic Medium

Considering the viscoelastic memory effect, we study the correlated motion of two hydrodynamically coupled colloidal particles, each of which confined in a harmonic potential well, in a Kelvin-type and Maxwell-type viscoelastic medium. We find that viscoelastic relaxation plays a significant role in modifying the correlation, particularly the cross correlation. We also find that both the real and imaginary parts of the response function are significantly different from the viscous medium case. In particular there is a phase shift between the vanishing imaginary part and the maximal real part of the response function in a viscoelastic medium. In addition imaginary part of the cross correlation response function exhibits a net energy loss （gain） behavior when the elasticity parameter of the medium is larger （smaller） than the critical value for Kelvin （Maxwell） viscoelastic fluid. Some implication of our results and their connection with previous works are discussed.