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Publications (42)
For experimental and numerical investigation of the repaired pipeline prototype, the small-scale vessel model was produced. At the first stage of the experiment, the deformed state of the vessel with an artificially created surface defect was studied by the tensometry method. At the second stage, a fiberglass wrap was installed on the steel vessel...
The possible contact interaction schemes for steel cylindrical shell and composite bandage fitted on it are considered. For each contact interaction scheme the mathematical model is developed. Possibility of implementation of different contact interaction scheme is numerically researched. It is shown that contact without separation is possible for...
A numerical procedure is developed for predicting the parameters of a yield criterion for metal-matrix composites on the basis of known mechanical properties of the matrix and fibers. The macrocriterion of yielding is taken in the form of an invariant quadratic function of average stresses, with the use of a fourth-rank tensor. Transition to the pl...
The paper presents a numerical technique for an evaluation of effective viscoelastic properties of fiber reinforced composite materials based on known mechanical properties of fibers and matrix. The set of numerical relaxation tests allowed calculating the tabular dependencies of components of a relaxation tensor for composite orthogonal weaving sc...
In this paper a composite plate with similar unidirectional fibers is considered. Assuming orthotropic structure, theory of elasticity is used for investigating the stress concentration. Also, complex variable functions are utilized for solving the plane stress problems. Then the effective characteristics of this plate are studied numerically by us...
Effective mechanical characteristics of fibrous composites are investigated. Calculations were performed with an ANSYS commercial package. Computational investigations of the stress state of a representative cell resulted in determining the effective elastic properties of an aligned fiber composite.
In this study, the influence of material damage and the Bauschinger effect on the autofrettage of thick-walled pressure vessels is investigated. Constitutive equations for the elasto-plastic deformation and damage processes are presented. Boundary value problems for a thick-walled cylinder and for a thick-walled sphere of constant thickness are for...
The paper is devoted to the research of the effective characteristics of 3D orthogonal nonwoven fibers composites. The results were received via ANSYS software package. In this research a volume element of fibers in cubic unit cell is considered. The effective elastic properties of fiber reinforced composite have been defined by the numerical stres...
The problem on the formation of stress fields in a pipeline with a repair composite band during the solidification of the polymer resin is considered. Heating of the composite material due to the heat release during the polymerization reaction is modeled. Two-dimensional pictures of location of the glass transition front during cooling are obtained...
The stress concentration must often be examined at two levels while analyzing the stress condition of composite materials. The macroconcentration depends on the presence of holes, notches and other local areas of a construction. Typical dimensions of macroconcentration distribution areas are of the order of 0,01-0,1 m. Macroconcentration analysis i...
In this paper the buckling problem is solved for the laminated composite structures from a thin-walled metallic cylindrical shell which is strengthened by fiber-reinforced polymers. The research concerning the influence of composite thickness and fiber orientation on axial critical buckling load is executed. For linear buckling problem, the purpose...
A mathematical model for the contact interaction of a cylindrical pipe with a composite band during its repair is constructed. A system of governing equations of the contact problem is formulated by using the Timoshenko theory of shells. An analysis of possible solutions is carried out for various combinations of geometric and elastic properties of...
The aim of this study was to compute the total stress concentration in reinforced composite plate with circular hole with respect to the volume ratio of the component materials in composite. The contour of the circular hole and its dependency on the structure of plates were calculated in order to study the behaviours of macro- and micro-stresses. I...
High cycle fatigue behavior of the compressor impeller is investigated. On the basis of numerical calculations of the stress-strain state of wheel the prognosis of life time is done. The results show relations between the number of cycles to failure and maximally possible stresses and displacements. Relation of cumulative fatigue damage is research...
In der vorliegenden Arbeit wird die Kontaktaufgabe über die Wechselwirkung einer langen Zylinderschale mit einer koaxialen zylindrischen Bandage aus einem Verbundwerkstoff untersucht. Der Verbundwerkstoff wird als ein homogenes orthotropes Material mit bekannten effektiven elastischen Eigenschaften modelliert. Basierend auf der klassischen Schalent...
Continuum damage mechanics approach has been used for analysis of the autofrettage process. General set of government equations of elastic-plastic bodies is derived by using the effective stress concept. Strain – damage coupling constitutive equations are developed on the base of plasticity relationships with bilinear kinematic hardening and kineti...
In this article, an energy-based model for predicting fatigue life and evaluation of progressive damage in a full composite wind turbine blade is proposed. Itis based on the assumption that the damage growth rate in a composite material depends on the maximum value of elastic strain energy per cycle. Design, finite element modeling, and dynamic ana...
A conventional material behaviour model can be extended to taking into account varying thermo-mechanical loading conditions in wide stress range. The motivation for developing this model is given by the well documented failure case study of high-temperature components at unit 1 of the Eddystone fossil power plant (Pennsylvania, USA), which have ope...
In this paper an energy-based model for predicting fatigue life and evaluation of progressive damage in composite materials is proposed. The damage model is based on the concepts of continuum damage mechanics. The applicability of the proposed energy model was studied in fatigue experiments on 10-layer composite laminates made of glass fabric impre...
The fatigue strength of STÉF-1 composite with glass fibers and epoxy-phenolic binder is investigated experimentally, and the damage accumulated therein is estimated. The investigations were performed on a special test bench DP-5/3 designed for determining the fatigue strength in bending of sheet specimens under symmetrical cycle of loading. The spe...
In this paper an energy-based model for predicting fatigue life and evaluation of progressive damage using plane-stress assumption is proposed. This model allows us to predict fatigue durability taking into account principal directions of the stress tensor relative to planes of elastic symmetry of material. First, the unknown parameters of this mod...
The conventional model of Kachanov-Rabotnov-Hayhurst continuum fracture mechanics is extended to cover the case of variable
temperature and strain hardening. The creep and damage rates are assumed to depend on temperature. The resulting model for
nonisothermal creep and damageability is implemented in a finite-element code of the general-purpose so...
The constitutive equation for the creep deformation rate, as well as the kinetic equations for hardening, recovery and damage processes, with a continuous functional dependence on temperature, are proposed. The material model is able to describe the primary, secondary and tertiary stages of creep behavior. The technique for the identification of pa...
A model which allows us to estimate the elastic properties of thin-walled structures manufactured by injection molding is presented. The starting step is the numerical prediction of the microstructure of a short-fiber-reinforced composite developed during the filling stage of the manufacturing process. For this purpose, the Moldflow Plastic Insight...
The autofretting of thick-walled cylinders with variable thickness is considered on the basis of a variational formulation of the corresponding elastic-plastic contact problem. The numerical solution is determined by the finite element method. We have chosen a material model which takes into account kinematic hardening and ideal Baushinger effect....
A variational method for refining the theory of shells based on power series expansion of displacements has been described. The particular case of a cubic approximation for the tangential displacements and a quadratic approximation for the deflections is considered in detail. A constitutive system of differential equations in the canonical form for...
In the production of composite aircraft structures the function of technological three-dimensional tooling is very important. It is practically impossible to implement a single manufacturing process without it.
Nonuniform heating, during technological processes, of shells of molding equipment leads to shell deformation. This results in the poor accuracy of pieces manufactured. That's why the stress-deformed state of the molding shell should be analyzed. The paper solves a separate problem of thermoelasticity for a thin-walled shell of molding equipment. D...
Laminated shells offer high strength and stiffness characteristics. Wide use of laminated shells in aircraft structures needs a development of the their efficient manufacturing technique from sheet preforms. The most advanced technique of manufacturing large-scaled line-forming parts for aircraft is stretch forming on punches. Analysis of supportin...
Complexity of a mathematical model is determined by a variety of the physical processes taking place in composite part production.
Major elements of a technique of the theoretical and experimental study of the mechanical properties of fiber-reinforced laminates are presented. A package of programs is based on macro- and micromechanical models of the composite. Analysis of the composite material strain in the neighbourhood of the loading application and close to the surface of...
A variational formulation is proposed for the problem of thin shell interaction with a smooth absolutely rigid stamp without taking friction into account in the contact domain. The shell material can be linearly or nonlinearly elastic. (Elastic-plastic problem /1/ can be reduced to the latter case under certain assumptions). Application of the Lion...
