Stability of Laminated Coatings Under Elastoplastic Deformation

A piecewise-homogeneous-medium model is used to consider a stability problem for layered elastoplastic coatings under plain strain. The theory of small elastoplastic strains is used. Characteristic equations are derived in an explicit form for a power dependence between the strain and stress intensities. The effect of the inelastic properties of layers on the phenomenon being studied is demonstrated by a specific example     

The Stability of Tribotechnical Laminated Polymeric Coatings

The stability of a laminated elastic coating with a polymeric bonding layer is considered within the framework of a piecewise-homogeneous model. The principle of critical strains is used in combination with the Volterra principle to account for the viscoelastic properties of polymers. Explicit expressions for determination of critical loads and time are derived. The range of variation in these parameters within which the coating does not buckle is found numerically     

The Stress State of Laminated Inhomogeneous Hollow Elliptic Cylinders Under a Surface Load

The stress problem is solved for inhomogeneous laminated hollow elliptical cylinders depending on their ellipticity and the rigidity of the middle layer. Discrete Fourier series are used. Illustrative calculations are carried out.     

Surface Instability of Laminated Materials of Regular Structure Under Triaxial Compression

The surface instability of laminated composites of regular structure is analyzed in a three-dimensional linearized formulation. A case is considered where the material is compressed by a surface distributed dead or follower load. Numerical results are presented for a specific problem.     

The Three-Dimensional Theory of Stability of Fibrous and Laminated Materials

An analysis is made of the results of investigations into the internal and surface instability of fibrous and laminated composites within the framework of the piecewise-homogeneous model and the equations of the three-dimensional linearized theory of stability. The possible buckling modes of the reinforcing elements in composites with either an elastic (polymeric) or elastoplastic (metallic) matrix are studied. The reliability domains of applied approximate design models are determined and some applications of results on fracture (due to structural instability) of unidirectional composites are presented     

Determination of the Mechanical Properties of Laminated Coatings at Various Temperatures

The basic physicomechanical characteristics of elastomer and polymer materials used in triboengineering as parts of laminated coatings are determined experimentally. The investigations are carried out under various mechanical and temperature loads. Results for some elastomer and polymer materials are presented as an example     

两级载荷下复合材料层板疲劳与寿命预测

研究了复合材料层板疲劳过程中的累积应变演化规律，建立了以累积应变为基础的非线性积累损伤法则，实验结果表明：文中提出的累积应变方法能够较好地反映加载次序效应，准确地预测了复合材料层板在两级载荷下的疲劳寿命。     

Nonlinear Deformation and Stability of a Noncircular Cylindrical Shell Under Combined Loading with Bending and Twisting Moments

A previously developed technique is used to solve problems of strength and stability of discretely reinforced noncircular cylindrical shells made of a composite material with allowance for the moments and nonlinearity of their subcritical stress–strain state. Stability of a reinforced bay of the aircraft fuselage made of a composite material under combined loading with bending and twisting moments is studied. The effects of straining nonlinearity, stiffness of longitudinal ribs, and shell thickness on the critical loads that induce shell buckling are analyzed.     

Fragmentation of High-Viscosity Fluids Under Pulsed Loading

Based on an analysis of experimental studies, it is shown that the determining mechanism of the layered fracture of a high-viscosity fluid is the shear instability of its structure and the swelling of the layered flow. The problem of shear flow of a high-viscosity fluid in a cylindrical channel is solved analytically. The results agree with experimental data.     

Nonstationary Vibrations of Plates Under Periodic Loading

The problem on the nonstationary vibrations of plates under periodic loading is formulated with regard for the damping factor and the initial conditions. A technique for solution of the problem is proposed. It is based on the method of integral Laplace transformations, the theory of residues, and the method of asymptotic approximations. Examples related to the change of the extinction coefficient are considered for different plate materials. A general formula for bending of the plate has been derived     

The Mechanics of Intermaterial Crackswith Contacting Faces Under Shear Wave Loading

International Applied Mechanics - A nonlinear problem for an intermaterial crack (cut) under a harmonic shear wave is solved using the method of boundary integral equations. A numerical analysis is...     

Short-Term Damage Micromechanics of Laminated Fibrous Composites Under Thermal Actions

A microdamage theory is constructed for laminated fibrous materials with transversely isotropic fibers and a porous isotropic matrix under thermal actions. Microdamages in the matrix are simulated by pores, empty or filled with particles of the damaged material that resist compression. The fracture criterion for a microvolume of the matrix is assumed to have the Nadai–Schleicher form, which takes into account the difference between the tensile and compressive ultimate loads, with the ultimate strength being a random function of coordinates with a power or Weibull distribution. The stress–strain state and the effective properties of the material are determined from the thermoelastic equations for laminated fibrous materials with a porous matrix. The deformation and microdamage equations are closed by the porosity balance equations corrected for the thermal effect. For various types of loading, nonlinear relations are derived for the coupled processes of deformation of a laminated fibrous material and microdamage of the matrix due to the thermal macrostrain. The effect of physical and geometrical parameters on these processes is studied.     

Thermoelastoplastic Stress—Strain State of Laminated Transversely Isotropic Shells under Axisymmetric Loading

A method is proposed for determining the thermoelastoplastic stress–strain state of laminated shells of revolution, made of isotropic and transversely isotropic materials, under axisymmetric loading. The method is based on the Kirchhoff–Love hypotheses for a layer stack, the theory of deformation along paths of small curvature for isotropic materials, and Hill's flow theory with isotropic hardening for transversely isotropic materials. The loading history is accounted for. The problem is solved by the method of successive approximations. Numerical examples are given     

Thermoelastoplastic State of Flexible Laminated Shells under Axisymmetric Loading Along Various Plane Paths

The paper presents a technique for thermoelastoplastic stress–strain analysis of flexible laminated shells of revolution under complex axisymmetric loading. The constitutive deformation equations are used to describe loading along arbitrary plane paths. The problem is solved by the method of successive approximations. A numerical example is given     

On the Dynamic Response of Laminated Glass Exposed to Impact Before Blast Loading

Experimental Mechanics - In this study, the effect of fragment or bullet impact before blast loading on laminated glass is studied experimentally. First, laminated windows consisting of two 3.8 mm...     

受分布载荷复合材料层合梁应力分析的一般理论

为了克服层合梁经典理论的缺点，提高层间应力的计算精度，提出了受分布载荷层合梁应力分析的一般理论。首先根据叠加原理将原始受力状态分解成对称与反对称受力状态。然后用正交完备的三角级数和勒让德级数构造这两种受力状态中每一铺层与层间胶层的位移场，并应用广义势能原理确定位移场中的待定系数，从而确定层合梁的位移场和应力场。同时，单层梁与单层梁之间的胶层被视为各向同性材料并且与其它材料层具有相似的力学特性，即具有有限厚度、有限弹性常数。计算结果显示,这种解法的收敛性非常好，根据物理方程与根据平衡方程得到的横向剪应力和正应力分布非常一致。     

Large Deformation of Nitinol Under Shear Dominant Loading

Full-field quantitative strain maps of phase transformation and plasticity in Nitinol under large shear-dominated deformation are presented. To achieve a shear-dominated deformation mode with relatively uniform stresses and strains, a shear compression specimen (SCS) geometry was utilized. Shear deformation appears to impede the development of the strain localization during phase transformation that is seen in uniaxial testing. The shear-dominant deformation of Nitinol in the plastic regime exhibits low hardening and results in the development of significant strain inhomogeneity.     

拉-拉循环荷载作用下的界面脱粘研究

应用弹性力学和断裂力学基本理论，基于剪滞模型，研究了纤维增强复合材料中纤维与基体界面在拉-拉循环荷载作用下的疲劳脱粘特性。建立了描述疲劳裂纹扩展的等效Paris公式，得到了界面疲劳脱粘扩展速率、脱粘应力以及脱粘界面的摩擦系数与循环加载次数的关系式。通过数值模拟计算，进一步分析了界面疲劳脱粘的力学机理。本文分析，考虑了疲劳加载引起的脱粘界面的损伤及损伤分布的不均匀性。同时还考虑了材料泊松比的影响。     

Durability of Thermoviscoelastic Bodies Under Long-Term Cyclic Loading

International Applied Mechanics - An energy failure criterion for thermoviscoelastic structural members subject to abrasive wear and dissipative heating is proposed. The criterion is used to...     

Numerical Study of Three-Dimensional Stability Problems for Laminated and Ribbon-Reinforced Composites

Classes of basic problems (classical problems and new problems derived by partial separation of variables) of the theory of elasticity and three-dimensional linearized stability are formulated in Cartesian coordinates. For each class of problems, the base scheme and the base system of equations are constructed and substantiated. They allow us to write explicitly the global mesh equations corresponding to an arbitrary problem from the class under consideration