Homogeneous horizontal and vertical seismic barriers: mathematical foundations and dimensional analysisV.A. Bratov, A.V. Ilyashenko, S.V. Kuznetsov, T.-K. Lin & N.F. Morozov
The concept of a vertical barrier embedded in soil to protect from seismic waves of the Rayleigh type is discussed. Horizontal barriers are also analyzed. The principle idea for such a barrier is to reflect and scatter energy of an oncoming wave by the barrier, thus decreasing the amplitude of surface vibrations beyond the barrier. Numerical FE simulations of a plane model are presented and discussed.
SYNTHESIS OF METALLIC COMPOSITE BASED ON IRON FRAME AND SiC NANOSTRUCTURES AND ITS STRENGTH PROPERTIESE.G. Zemtsova, D.V. Yurchuk, Yu.V. Sidorov, B.N. Semenov, N.F. Morozov & V.M. Smirnov
The article discusses a new approach to the synthesis of metallic composite materials based on nanostructuring of a metal frame (on the example of iron) by SiC nanostructures (10-50 nm). Optimal conditions are established for the nano-SiC coating on the porous Fe surface during sequential chemisorption of Cl2Si(CH3)2 and CH4 molecules from the gas phase. The resulting composite possesses enhanced strength in comparison with the best steel samples although the residual porosity (up to 5%)...
Experimental creep curves and long-term strength curves for viscoelastic compressible materials have been obtained at room temperature for a wide range of stresses. The residual density change (loosening) of the material is considered as the main damage factor. A modified creep equation for the loosening medium is proposed, which can describe the second and third regions of the creep curve. Based on proposed equation the criterion of long-term strength is formulated. It is shown that...
This study is concerned with the modeling of plate buckling induced by a chemical reaction and is inspired by the observation that buckling may be a mechanism of stress relaxation in Si-based anodes in Li-ion batteries. A chemical reaction is localized at a sharp interface and accompanied by transformation strains, which produce internal stresses. If external supports restrict the deformation of the plate, buckling may occur. At the same time, mechanical stresses affect the kinetics...
Based on the temperature relaxation model of plasticity, the effects of the irreversible deformation of metals that appear under conditions of various temperature and strain rate regimes are studied. The appearance of the yield drop on the dynamic deformation dependence for 2519А aluminium alloys at a temperature of -45°C in the range of strain rates 1000–4000 s–1 is predicted. Dynamic dependencies for Al-13Mg aluminium alloys at temperatures 325°C and 425°C are constructed. The temperature relaxation...
SSRT method: application to studying the mechanism of stress corrosion cracking in steels and alloys (overview)A.А. Kharkov , A.A. Alkhimenko, N.O. Shaposhnikov & E.L. Alekseeva
The paper briefly describes the slow strain rate testing (SSRT) method used for steels and alloys, considering the stress and strain criteria for assessing the sensitivity of materials to stress corrosion cracking (SCC). We pointed out the clear benefits of the SSRT method over static SCC testing. We reviewed the modern theories of the main possible mechanisms of SCC, typically including alternating stages of anodic dissolution and hydrogen embrittlement during the initiation and propagation of...
Engineering practice shows that the design of modern structures and technical components requires adapting existing methods for testing materials to dynamic load conditions. This work discusses the experimental and theoretical basis for determining and predicting critical stresses in quasi-brittle materials (such as concrete, rock, organic glass, etc.) over a wide range of loading rates provided by different test methods and equipment. Standard tests for compression, splitting and bending are presented. The incubation time approach is...
Surface growth of solids includes a wide variety of processes starting from additive manufacturing technologies and ending with plenty of biological problems. Model of surface growth based on the expression of the configurational force, derived from fundamental laws and entropy inequality, is offered in the present paper. A new expression for the configurational force called surface growth force, which controls growth and resorption, is used. Analysis of the applicability of the developed model was carried...
In the present paper, we provide a theoretical approach to the analysis of nanopore morphological stability under diffusion taking into account surface elasticity. It is assumed that the pore shape may change during stress relaxation. The surface atomic flux is caused by the nonuniform distribution of chemical potential, which depends on bulk and surface stresses as well as pore surface curvature. The change in surface relief is described by the linearized evolution equation, which is...
The paper presents comparative numerical analysis of two ceramic materials subjected to impact loading. ZrO2(Y2O3) and Al2O3 ceramics are studied. The main objective of the work is to study influence of various material parameters on ballistic performance of ceramic materials and on characteristics of the dynamic fragmentation process. The applied numerical scheme is based on finite element method and incubation time fracture criterion. Results on fracture surface area, residual impactor velocity, fragment size distribution are...
Polymers and polymer-based materials are intensive implemented in many areas of engineering practice. These applications frequently have a very high performance demand, which makes their long-term characteristics of paramount importance. These materials were subject to degradation due to environmental factors, including light, temperature, stress, and others. Because of aging process, the physical and mechanical properties of these materials are significantly changed. This paper is devoted to the experimental investigations of this problem. The research program...
St Petersburg University8
Institute of Problems of Mechanical Engineering4
Saint Petersburg State University3
Peter the Great St. Petersburg Polytechnic University3
Moscow State University of Civil Engineering1
Institute for Problems in Mechanics1
National Chiao Tung University1
N. I. Lobachevsky State University of Nizhny Novgorod1
Technical University of Berlin1