Physicomechanical Characteristics Of Material Research Articles

Stab resistance of bulletproof vests. A conceptual model of test bench

This paper presents a conceptual model of a stand to test the physico-mechanical characteristics of materials used in the soft panels of bulletproof vests for their stab resistance to cold weapons having a sharpened blade portion firmly and rigidly attached to handle. In the process of conceptual design of the model, the requirements and norms set out in two of the leading standardization documents used to determine the stab resistance of the bulletproof vests: the standard of the US National Institute of Justice -NIJ 0115.00, Stab Resistance of Personal Body Armor, and the UK Police Standard - HOSDB 2007. Part 3 -Knife and Spike Resistance, have been taken into account. 3D models of the stand and its individual constructive elements were developed, on the basis of which were offered real elements and devices for its elaboration. The designed stand is technologically accessible, inexpensive and easy to manufacture and install. It can be used to pre-determine the stab resistance of different types of materials and their combinations used in the soft panels of the bulletproof vests in the process of improving their structure. Availability of such stands in the equipment of the producers laboratories involved in this type of activity would reduce costs and shorten the evaluation time of the tested materials in order to verify their compliance with standard requirements since only samples showing the highest stab resistance will have to be sent for testing in certified and accredited laboratories.

Two-Layer Ferrocement Shells Stress-Strain State Modeling under the Fire Conditions

The article deals with the issues of strength calculation of two-layer ferrocement shells under fire conditions, taking into account the physical nonlinearity of the material. The change in the physicomechanical characteristics of materials under the action of temperature is taken into account. The solution of model problems for shallow shells of double curvature is presented.

Structure formation upon barocryodeformation of a steel of austenitic class

Data are given concerning the opportunity of applying barocryodeformation (plastic deformation under the conditions of severe uniform compression at cryogenic temperatures) to produce ultrafine-disperse martensitic structure in Kh18N10T steel (≤0.08 C, 18 Cr, 10 Ni, <0.7 Ti, ≤2 Mn, ≤0.8 Si (wt %)), which ensures an increase in the physicomechanical characteristics of material that are unattainable when using other types of treatment. Experiments are described that make it possible to explain the high (in spite of the presence of large forces of uniform compression) rate of completion of the martensitic transition upon the deformation of the steel under such conditions.

Diagnostics of corrosive state of main gas pipelines with module probe technology

A new method of measuring the corrosion rate of pipelines based on integration of the principle of polarization resistance into the module probe technology is developed for diagnostics of the corrosive state of pipelines. The experimental setup and the method for measuring the corrosion rate of metal objects in soil are developed. The efficiency of the setup and the possibility of recording the corrosion rate under the condition of long preliminary polarization are demonstrated. The results are of interest for development of new variants of diagnostics of the corrosive state of underground metal objects, technical diagnostics, and studies of physicomechanical characteristics of materials.

COLLABORATION BETWEEN THE PHYSICOMECHANICAL INSTITUTE OF THE UKRAINIAN NATIONAL ACADEMY OF SCIENCES AND THE FGUP OF THE DESIGN OFFICE OF CHEMICAL AUTOMATICS IN THE FIELD OF CREATION OF OXYGEN-HYDROGEN LIQUID-PROPELLANT ENGINES

The collaboration between the Design Office of Chemical Automatics dealing with the design and production of liquid-propellant rocket engines and the Karpenko Physicomechanical Institute, a recognized scientific leader in the field of physicochemical mechanics of materials, began in 1976 from discussions on the interesting results of fatigue tests of structural materials with protective coatings under the conditions of high-frequency ( f ∼ 20 kHz) loading obtained in the Design Office of Chemical Automatics. The high scientific level of the discussion of the presented results stimulated the mutual interest in the solution of scientific and technical problems put forward to both collectives and, naturally, led to the revelation of the points of joint application of forces. In the early 1970s, the Design Office of Chemical Automatics began to develop an RD0120 powerful oxygenhydrogen engine for the space “Energiya-Buran” complex and was in urgent need of information on the serviceability of structural materials in a medium of high-pressure gaseous hydrogen. At that time, the Physicomechanical Institute had accumulated sufficient experience in the investigation of the serviceability of structural materials in hydrogen-containing oil and gas media, had advanced testing and methodological data, considerable experience in the design of nonstandard test equipment, and, first of all, highly skilled scientific personnel. In the discussions of leaders and specialists of both organizations, the principal direction of collaboration was revealed, namely: the formation of a powerful research center based on the Physicomechanical Institute that would be able to carry out complex investigations of the influence of hydrogen on physicomechanical characteristics of materials under conditions simulating the temperature-force loading of structural materials. The leaders of the Ukrainian Academy of Sciences and the Ministry of General Engineering of the USSR supported this idea and made a common decision on the formation of the Interdepartmental Research Center “Proton.” On the basis of its own experience, information from leading research centers, and the specification of the Design Office of Chemical Automatics, the Physicomechanical Institute designed and launched a laboratory complex equipped with unique test equipment of its own design and production, which enables one to carry out experiments with ultrapure hydrogen at a pressure up to 120 MPa in the temperature range from 20 to 1273 K. In this work, K. B. Katsov, V. I. Tkachev, and other employees took an active part under the guidance of V. V. Panasyuk. In the course of joint works performed according to the coordinated program, more than thirty sorts of promising material were investigated, the characteristics of short-term and long-term strength under tension and two-axial loading, low- and high-cycle fatigue, and resistance to the action of thermal cycles were obtained, and cyclic crack resistance and “hydrogen degradation” were studied [1]. The researchers determined the criterial parameters of “hydrogen degradation” of composite materials, which characterize the serviceability of structural elements and are used in strength analysis, and developed and experimentally verified the methods of evaluation of strength and durability of structures (including structures containing defects) operating in hydrogen [2]. The dependences of mechanical characteristics on temperature, pressure of gaseous hydrogen, loading rate, preliminary saturation, and presence of contaminating impurities in hydrogen were investigated and systematized [3, 4], and the influence of various metallic, oxide, and nitride barrier coatings was checked [5].

Effect of temperature-induced variations in the physicomechanical characteristics of materials on the thermal-stress distribution associated with elastoplastic deformations

Effect of temperature-induced variations in the physicomechanical characteristics of materials on the thermal-stress distribution associated with elastoplastic deformations