Begell House
Composites: Mechanics, Computations, Applications: An International Journal
Composites: Mechanics, Computations, Applications: An International Journal
2152-2057
1
1
2010
LINEAR DYNAMIC NEURAL NETWORK MODEL OF A VISCOELASTIC MEDIUM AND ITS IDENTIFICATION
For identification of the behavior of viscoelastic media with small deformations the linear dynamic neural network model is suggested. The model realizes the principle of an adaptively hierarchical superstructure. In order to reach the specified level of the identification error (10−12) the model changes its structure automatically from the 3rd to the 24th order of complexity. The neural network model, compared to other known phenomenological models of viscoelastic media, possesses a higher operation speed, allows use of parallel computational procedures, and realizes an adaptively hierarchical principle of construction. A small error of training the linear nonstationary dynamic model without feedback can be reached only in the presence of a huge initial massif of experimental data.
Yuri G.
Yanovsky
Institute of Applied Mechanics of Russian Academy of Sciences, 32A Lenin Ave., Moscow, 119991, Russia; Moscow Aviation Institute (State University of Aerospace Technologies), Moscow, Russia
Yu. A.
Basistov
Institute of Applied Mechanics, Russian Academy of Sciences, Moscow
1-23
ANALYTICAL STUDY OF STEFAN-TYPE PROBLEMS IN COMPOSITES WITH AN ARBITRARY NUMBER OF MOVING BOUNDARIES OF PHASE TRANSITIONS
The problem on heat transfer in semi-infinite bodies with an arbitrary number of unsteady moving boundaries of phase transition (Stefan-type problems) has been formulated and solved analytically. Such problems arise in high-temperature heating of composite materials when destruction of binders is accompanied by formation of moving boundaries of the start and end of phase transitions, boundaries of mass entrainment, etc. An analytical solution of the Stefan-type problem has been obtained at an arbitrary number of unsteady moving boundaries and heat transfer in the presence of two moving boundaries has been studied in detail.
Ek. L.
Kuznetsova
Moscow Aviation Institute (National Research University), Moscow, Russia
I. A.
Selin
Moscow Aviation Institute (State Technical University), Moscow
V. F.
Formalev
Moscow Aviation Institute (National Research University), Moscow, Russia
25-35
ROLE OF TRIBOELASTICITY IN CYCLIC BEHAVIOR OF ELASTOMERIC NANOCOMPOSITES
A triboelastic model of elastomeric nanocomposite and specific features of its mechanical behavior in cyclic tests are considered. The model takes into account two structural parameters that mainly specify the mechanical behavior of nanocomposites: elastic nonlinearity of the elastomeric matrix and the strength of its adhesion with the filler. The model may be useful for specialists in materials science who are involved in developing composites with prescribed mechanical properties.
V. V.
Moshev
Institute of Continuous Media Mechanics, Ural Branch of the Russian Academy of Sciences, 1, Akad. Korolev Str, Perm, 614013
S. E.
Evlampieva
Institute of Continuous Media Mechanics, Ural Branch of the Russian Academy of Sciences, 1, Akad. Korolev Str, Perm, 614013
37-44
STRENGTH AND LONGEVITY OF POLYMERS AND COMPOSITES UNDER VARIABLE TEMPERATURE−FORCE EXTERNAL CONDITIONS
The destruction of a material is considered as the process of accumulation in time of internal micro damages. The notion of the material memory-retention of the inflicted damages is introduced. The statement of the direct and inverse problems of predicting the strength and longevity of polymers and composites based on them under variable temperature-force conditions of their testing or maintenance is given. To solve these problems for materials with an arbitrary type of memory, the generalized principle of the superposition of damages has been formulated. Based on it, the solution of the direct problem of prediction is given. Examples are considered. Explanation of the experimentally observed anomalies on the diagrams of the temperature-time dependence of strength is given.
A. A.
Valishin
M. V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow
T. S.
Stepanova
M. V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow
E. M.
Kartashov
M. V. Lomonosov Moscow State Academy of Fine Chemical Technology, Moscow
45-62
STRUCTURAL-PHENOMENOLOGICAL MODEL OF THE MECHANICAL BEHAVIOR OF RUBBER
Filled elastomers (rubbers) are composite materials distinguished by the complex structure and specific properties due to the interaction of the filler and binder at the phase interface. A structural-phenomenological model of the viscoelastic behavior of rubber is suggested in the present work. Apart from the plastic, elastic, and viscous elements, the model involves a new type of elements − transmission ones that connect the structural deformations of the matrix at the nanolevel with the deformation of the material. A comparison with the experiment has demonstrated a good reproducibility of the Mullins softening effect and the viscoelastic behavior of rubber in a wide range of the amplitudes of deformation. The determination of the unknown constants of the model is split into several independent stages, which substantially simplifies practical realization.
A. L.
Svistkov
Institute of Continuous Media Mechanics, Ural Branch of the Russian Academy of Sciences, Perm, Russia; Perm State National Research University, Perm, Russian Federation
I. A.
Morozov
Institute of Continuous Media Mechanics, Ural Branch of the Russian Academy of Sciences, 1 Acad. Korolev Str, Perm, 614013, Russia and Perm State National Research University, 15 Bukerev Str., Perm, 614990, Russia
63-79
INFLUENCE OF THE COATING THICKNESS ON STRENGTH OF THE COATING−BASE MATERIAL COMPOSITE. NUMERICAL SIMULATION
Special features of deformation and fracture of a material with coating of different thickness in tension have been investigated. The boundary-value problem in the plane-strain formulation is solved numerically by the finite-difference method. In calculations, a composite structure is taken into account explicitly. It is found that for thick coatings, a value of stress concentration near the "coating−base material" interface does not change with changes in the coating thickness whereas in the region of small thicknesses it increases nonlinearly with a decrease in the coating thickness. This effect is observed at the elastic stage of composite deformation, it enhances as plastic deformation develops in the base material, and amounts to 25% at the prefracture stage. Recommendations that could be useful for optimization of the coating thickness are given.
Ruslan R.
Balokhonov
Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Tomsk, Russian Federation
V. A.
Romanova
Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, Tomsk
81-93