基于应变的Ⅰ/Ⅱ/Ⅲ复合型断裂准则

将已有的适用于平面断裂的最大周向应变（MTSN）准则,推广到适用于空间三维断裂的断裂准则.并具体讨论了Poisson(泊松)比对复合型断裂的面内断裂角与面外断裂角及断裂包络图的影响.Ⅰ/Ⅲ复合型断裂时,面外断裂角与Poisson比无关.Ⅱ/Ⅲ及Ⅰ/Ⅱ/Ⅲ复合型断裂条件下,面内断裂角随着Poisson比的增大而减小,面外断裂角随着Poisson比的增大而增大.在复合型断裂条件下,包络图均随着Poisson比增大而减小.且Poisson比对断裂包络图的影响大于面内断裂角,对面外断裂角影响最小.将本准则理论预测值与多组实验数据进行对比,预测值与实验值吻合较好,可知推广的MTSN准则能够较好地预测三维断裂.     

A method of constructing weighting functions for a circular crack

A general formulation is used to consider a static problem for a linearly elastic body with internal circular crack of normal separation. It is shown that the corresponding weighting function enabling a direct calculation to be made of the stress intensity factor (SIF) under arbitrary loading conditions is equal to the product of the axisymmetric weighting function and Poisson's kernel. The known axisymmetric solution /1/ is used to construct, as an example, the weighting function for a circular crack in an unbounded inhomogeneous body with periodic law of variation in the value of Poisson's ratio. An asymptotic analysis of the solution obtained is carried out for a material with rapidly oscillating elastic characteristics.

Some problems of the inhomogeneous theory of elasticity were studied for bodies with variable Poisson's ratio in /1–4/.     

Thermal creep of polyethylene in the presence of thermal cycling

The temperature-time dependence of Poisson's ratio and the volume relaxation of LDP is investigated in the case of uniaxial tension. It is established that at elevated temperatures and loads the material becomes denser and Poisson's ratio exceeds 0.5. It is shown that the (t) curves and the temperature dependence of the instantaneous Poisson's ratio are nonmonotonic, while the nature of the (t) relaxation changes qualitatively as a certain temperature region is entered and the stress is increased.Mekhanika Polimerov, Vol. 4, No. 3, pp. 421–427, 1968     

Variation of Poisson's ratio in the course of a complete one-dimensional creep cycle

By solving the system of differential equations of a standard solid, expressions are obtained for determining Poisson's ratio with allowance for the characteristics of volume and shear strain. For a material having values of Poisson's ratio in creep (0)<0.5 and ()=0.5, Poisson's ratio in reverse creep (t)^rev>0.5. The volume strains that occur at the beginning of reverse creep have the same magnitude as the creep volume strains, but the opposite sign. The law of disappearance of the volume strains is the same for creep and reverse creep.Mekhanika Polimerov, Vol. 4, No. 2, pp. 227–231, 1968     

Axisymmetric isospectral annular plates and membranes

A simpler ‘conditional’ form of the vibrating plateequation for which all the physical parameters may be spatiallyvarying is found when the relationship D(1 – v) = constantis satisfied between flexural rigidity and Poisson's ratio.A method of coordinate inversion is used to find a family ofinhomogeneous clamped annular plates (with axisymmetric spatiallyvarying density, thickness, Young's modulus, and Poisson's ratio)which have the same complete frequency spectrum as a standardhomogeneous clamped annular plate of the same inner and outerradii. In particular, these inhomogeneous plates have inversefourthpower radial dependence of density. General radial power-lawtransformations are also considered, leading to conclusionsfor the axisymmetric vibration spectra. Various results forcircular and annular membranes also emerge from the analysis.     

Determination of coupled creep functions from experimental creep curves

A method is given for constructing the coupled creep functions g(t) from the experimental longitudinal creep curves and the known Poisson's ratio. It is shown that for this purpose it is sufficient to substitute for one of the parameters of the singular kernel a quantity containing the Poisson's ratio and the parameter determined from the solution of the elastic problem.I. M. Gubkin Moscow Institute of the Petrochemical and Gas Industry. Translated from Mekhanika Polimerov, No. 2, pp. 216–220, March–April, 1974.     

Effect of temperature and anisotropy on the elastic constants of oriented glass-reinforced plastics

The experimental temperature dependence of the modulus of elasticity and Poisson's ratio are presented for SVAM oriented glass-reinforced plastic. The possibility of treating SVAM sheet as orthotropic at elevated temperatures is demonstrated.Institute of Chemical Physics, AS USSR, Moscow. Translated from Mekhanika Polimerov, Vol. 4, No. 6, pp. 1026–1032, November–December, 1968.     

Dependence of the acoustic and mechanical properties of polyethylene on temperature and cyclic cooling and heating

The low-temperature stability of polyethylene is confirmed by acoustic and mechanical investigations. Data are given on the dependence of the acoustic and mechanical properties of polyethylene on temperature and repeated cyclic cooling to –50° and heating to +60°C, together with information on the change in Poisson's ratio and volume during deformation.Mekhanika Polimerov, Vol. 1, No. 3, pp. 145–150, 1965     

Experimental determination of Poisson's ratio of fissured media

Some experimental studies that Poisson's ratio of fissured media can be small and even negative. A possible explanation for this circumstance is thus proposed on the basis of the application of the matrix method to fissured media.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 156, pp. 143–147, 1986.     

Poisson's ratio of polyethylene in creep recovery

It has been experimentally and theoretically established that the Poisson's ratio of polyethylene in creep recovery has a value ^rec>0.5.Mekhanika Polimerov, Vol. 4, No. 3, pp. 563–564, 1968     

Method of determining the volume and shear characteristics of elastico-viscous hereditary media from uniaxial-tension (compression) experiments

A method is proposed for determining the elastic constants — instantaneous modulus of elasticity, Poisson's ratio, shear modulus, bulk modulus, and the shear and volume influence functions — the shear creep kernel, the shear creep rate kernel, and the corresponding relaxation kernels from the data of creep or relaxation tests.Moscow. Translated from Mekhanika Polimerov, No. 4, pp. 754–758, July–August, 1969.     

Elastic characteristics of ferrocement reinforced with woven meshes

Applying structural mechanics methods for composite materials, we have worked out a procedure for predicting the elasticity modulus, the shear modulus, and Poisson's ratio for ferrocement taking into account the elastic properties of the components, the wire diameter, the mesh size, and the distance between the meshes. The results make it possible to exploit the potential of such reinforcement to the fullest.Translated from Mekhanika Kompozitnykh Materialov, Vol. 30, No. 4, pp. 526–530, July–August, 1994.     

Separation of variables as a means of solving the mixed boundary-value problem of viscoelasticity

The quasistatic mixed boundary-value problem is considered for a viscoelastic body with constant Poisson's ratio. A method of reducing viscoelastic problems to the solution of a series of uniform elastic problems is described. The convergence of the method is proved. The method is illustrated with reference to the solution of a specific viscoelastic problem. Tabulated influence functions of the Abel type are used in the solutions.Moscow M. V. Lomonosov State University. Translated from Mekhanika Polimerov, No. 4, pp. 588–596, July–August, 1969.     

Method of approximations for solving problems of the linear theory of thermoviscoelasticity

A general approximate method of solving problems of the linear theory of thermoviscoelasticity is proposed. Use is made of the Laplace transformation and certain properties of the dependence of solutions to problems of the theory of elasticity on Poisson's ratio that make possible a simple approximation. As a result, the inverse transforms become elementary and the general solution of the problem is expressed by creep and relaxation functions.Mekhanika Polimerov, Vol. 4, No. 2, pp. 210–221, 1968     

Study of the effect of test piece geometry on the propagation velocity and logarithmic decrement of longitudinal vibrations in fluoroplastics

The effect of the geometry of teflon test pieces on the speed of sound and the logarithmic decrement of longitudinal vibrations has been investigated. Conditions for the determination of the speed of sound in an infinite medium and in a rod have been obtained. A method is given for determining the dynamic moduli of longitudinal elasticity, the shear modulus, and the dynamic Poisson's ratio on test pieces in the form of rods and prisms, starting with a length of 30 mm.Mekhanika Polimerov, Vol. 2, No. 4, pp. 557–564, 1966     

页岩储层各向异性对水平井坍塌压力的影响

为揭示层理页岩强度各向异性对水平井井壁坍塌压力的影响规律,对取自四川盆地龙马溪组页岩钻井不同层理角度的岩芯,通过岩芯观测、偏光显微镜、扫描电镜试验分别从宏观和微观角度研究了页岩层理特征,并基于单轴抗压强度研究了页岩强度各向异性特征.层理结构发育导致页岩呈现出显著的各向异性特征,粗略地将页岩视为各向同性体及简单采用Mohr-Coulomb准则作为破坏判据,使得预测的维持井壁稳定的坍塌压力不能满足安全钻井的需要.该文在研究层理地层岩石力学特性的基础上,采用横观各向同性地层井周应力分析模型,研究了弹性模量及地应力各向异性比对井周应力的影响;并结合考虑中间主应力的Mogi-Coulomb判据,分析了井壁坍塌压力对弹性模量E和Poisson(泊松)比ν各向异性比值变化的敏感性.实例分析结果表明:弹性模量和水平地应力各向异性比值的变化会对井周应力产生较大影响;Poisson比各向异性对井壁坍塌压力没有明显影响,而弹性模量比值的变化对井壁坍塌压力影响较大;横观各向同性地层中井壁坍塌压力与储层水平和垂直方向的硬脆性强弱关系有关,弹性力学参数各向异性既有可能利于井壁稳定,也可能更易导致井壁的剪切破坏;在实际工程中应根据储层岩石水平和垂直方向的硬脆性强弱关系,确定安全钻井液密度窗口.该结果对现场施工具有很好的指导意义.     

Stability of transversely isotropic annular plates with low shear resistance

The stability differential equations of a cylindrically orthotropic circular plate are obtained on the assumption of an axisymmetric buckling mode with allowance for transverse shears. These equations are solved for the case of a transversely isotropic material when the inner and outer edges of the plate are identically loaded by uniformly distributed radial forces. The transcendental equations for the critical load parameter are constructed for various edge conditions. The dependence of this parameter on the boundary conditions and the relative thickness of the plate, Poisson's ratio, and the ratio of the Young's and shear moduli of the material are investigated. Certain conclusions are reached concerning the design of reinforced-plastic plates.Institute of Polymer Mechanics, Academy of Sciences of the Latvian SSR, Riga. Translated from Mekhanika Polimerov, No. 5, pp. 872–880, September–October, 1969.     

集中力作用于剪切模量沿深度线性变化的半空间的公式

根据一个引理和一个假设,本文绘出集中力作用于泊桑比v为常数和剪切模量G沿深度线性变化的半空间的公式.当用积分方程法分析桩和其它地学工程问题时,这些公式可以用作一近似的基本解.     

Effective moduli of particulate solids: Lubrication approximation method

To efficiently calculate the effective properties of a composite, which consists of rigid spherical inclusions not necessarily of the same sizes in a homogeneous isotropic elastic matrix, a method based on the lubrication forces between neighbouring particles has been developed. The method is used to evaluate the effective Lamé moduli and the Poisson's ratio of the composite, for the particles in random configurations and in cubic lattices. A good agreement with experimental results given by Smith (1975) for particles in random configurations is observed, and also the numerical results on the effective moduli agree well with the results given by Nunan & Keller (1984) for particles in cubic lattices.     

用白光散斑方法测量动态变形

本文提出一个简便的,用多火花动光弹仪进行动态变形测量的白光散斑方法,用此方法不但可以进行动态大变形测量[1],也可动态小变形测量.如果和动光弹等色线结合,可以同时获得被测材料的弹性模量、泊松比、材料条纹值参数.