Solid State Phenomena Vol. 243

Abstract: It is a wll-recognized fact that effective damping of vibrations in the structure containing piezo-electrical elements strongly depends on their distribution throughout the structure. In this paper, we consider the possibilities of applying the problem on natural vibrations of elecro-elastic and electro-viscoelastic deformable bodies for identification of optimal location of piezo elements. The results of numerical simulation of the optimal piezo element arrangement in the structure, providing generation of the maximal electric potential at the prescribed resonance frequencies, are presented. The investigation has been carried out for the prototype of the plane wing, representing cantilevered symmetrical and nonsymmetrical trapezoidal plates. The possibilities of applying the problem of natural vibrations for the purpose of optimal performance of piezo elements as sensors and actuators are analyzed.

Abstract: The finite element Deform-2D/3D simulation system was used to investigate the technological process of hot-forming of metal block. Numerical modeling of plastic working has been carried out to evaluate the stress and strain fields generated in a steel ingot during two stages of the technological process – free upsetting and subsequent press forging and to define forces that will specify technical characteristics of the equipment capable of performing these operations.

Abstract: One of the crucial points in making materials with embedded optical fiber sensors is obtaining information about stress-strain state which helps to asses the influence of embedded optical fibers on integral mechanical properties of the structure and redistribution of stresses and strains in the area around optical fibers. In this paper models of woven composite material with embedded optical fibers are studied with numerical results achieved with the help of finite element method in case of GFRP VPS-33 material with fabric filler T-10-14 and epoxy resin ENFB-2M. Numerical results about the change of stiffness parameters of plate specimens in cases of tension and bending are obtained. Evaluation of stress state change near embedded optical fiber in different cases of optical fiber orientation with respect to loading and in the presence and absence of resin pocket defect with polyamide optical fiber coating taken into account is given in this study.

Abstract: Numerical models describing crack formation and growth in reinforced concrete give reasonably good estimates of the bearing capacity and durability of an element of the structure without expensive full-scale tests. In this paper, a finite-element model is proposed to study the failure of a rectangular reinforced concrete beam subjected to four-point bending. The results of quasi-static simulation and the data obtained by taking into account inertial forces are compared. The feasibility of taking into account inertial forces is justified by assessing the contribution from kinetic energy (above 30%) at the instant of crack formation to the total mechanical energy of the system. Comparison of the experimentally obtained and calculated crack patterns is performed. It is shown that the mechanism of debonding between the reinforcement and concrete plays a key role in cracking.

Abstract: This paper presents the results of experimental and theoretical studies justifying the possibility of using infrared (IR) thermography for detection of deformation debonding of composite material from a reinforced concrete structure that occurs under operating conditions and develops according to the cohesion scenario. The analysis of the results allowed us to determine the optimal inspection parameters of IR thermography to assure best registration of the presence of fiber composite material debonding from the surface of a concrete structure. It has been found that the most accurate and timely information about debonding in a carbon fiber sheet/epoxy/concrete/delamination/concrete system can be obtained during the cooling stage after pulse heating of the structure surface, since at this stage the magnitude of thermal response to debonding reaches its maximum.

Abstract: It is important to control the deformation condition of building foundations, which can change throughout period of operation. One of the criteria for evaluation of deformation of foundations is the vertical differential settlement. The hydrostatic leveling system is a technique to measure differential vertical settlements of foundation. It is possible to provide many standard constructions with sufficient accuracy of measuring settlements by using technically simple variants of the hydrostatic leveling system. Examples of using hydrostatic leveling systems for five-storey brick masonry building, monolithic reinforced concrete building and a historic 18th century building are given.

Abstract: The behavior of specimens dynamically loaded during the split Hopkinson (Kolsky) bar tests in a regime close to simple shear conditions was studied. The lateral surface of the specimens was investigated in-situ using a high-speed infra-red camera CEDIP Silver 450M. The temperature field distribution obtained at different time allowed one to trace the evolution of plastic strain localization. The process of target perforation involving plug formation and ejection was examined using a high-speed infra-red camera and a VISAR velocity measurement system. The microstructure of tested specimens was analyzed using an optical interferometer-profiler and a scanning electron microscope. The development of plastic shear instability regions has been simulated numerically.

Abstract: This paper introduces the methodology of microstructural characterization of fibrous composites using correlation functions of different orders. Its implementation is demonstrated on several examples of modeled representative volume elements. The ways of obtaining values of the functions as well as the procedure of their approximation are presented. The possible applications of such methodology are discussed.

Abstract: The solution of boundary-value problem in mechanics of polycrystalline materials is represented as perturbation series upon intergrains interaction like it is made in quantum fields theory. The terms of this series satisfy the infinite set of integral equations that reduced to systems of linear algebraic equations if to neglect the heterogeneities of strains within domain of individual grain. The method allows to take into account a microstructure of materials. Few examples of method application are demonstrated.

Abstract: A methodology and a numerical algorithm of solving boundary problems of mechanics of deformable crystallizing elastic polymer media have been developed. A class of problems describing processes taking place in polymer products during their manufacturing is considered. Due to the significance of shrinking deformations the problem is considered within finite deformations theory. Constitutive relations are built on base of Peng-Landel potential. A ‘weak’ variation problem statement based on Galerkin approach is used. The offered algorithm is based on linearization methodology when small deformations are applied to finite ones. Deformation process is considered as a sequence of transitions through intermediate configurations. This approach makes possible to bring the received solution to the sequence of linearized boundary problems for which effective numerical algorithms have been designed. Numerical procedure is based on the technology of finite element method. Increments of displacements on the considered time step are taken to be nodal unknowns. The offered algorithm is applied to solution of the problem concerning the polyethylene pipe deformation during its manufacturing. Main advantages of the proposed algorithm have been defined.