Mykola Chausov

Strain field evolution on the surface of aluminum sheet alloys exposed to specific impact with oscillation loading

Strain field evolution on the surface of aluminum sheet D16 and 2024-T3 alloys has been analyzed during static deformation and during specific high-speed impact and oscillation loading—dynamical non-equilibrium process. Experiments have been conducted using an original mechanical testing technique and a specially developed software solution for non-contact study of strain field using digital image correlation fitted with a high-speed camera. It has been established that deformation process kinetics for tested aluminum alloys after a dynamical non-equilibrium process during further static deformation changes as compared with a process of static deformation mainly manifests itself in the increase in general alloy ductility and delay in “neck formation.” It has been shown that strain field is an important indicator for deformation band structure formation in the tested materials.

Self-Organisation of the Heat Resistant Steel Structure Following Dynamic Non-Equilibrium Processes

Using an original experimental methodology and software for contactless investigation into strains applying the method of digital image correlation, conditions for DNP realization in the test setup with pre-set rigidity have been found. Strain velocities have been determined to be equal to 2...10 s–1 in the processes of forming and developing a dissipative structure of heat resistant steel under the DNP (dynamic non-equilibrium process).

Enhancing plasticity of high-strength titanium alloys VT 22 under impact-oscillatory loading

Abstract The purpose of this paper is to provide new experimental data for high-strength VT 22 titanium α + β-type alloy under impact-oscillatory loading and dynamic non-equilibrium process. Based on the performed experimental studies, it was found that overall plastic deformation of this alloy can be increased by a factor 2.75 compared with its initial state without significant loss of strength. To achieve this goal, a new methodology to study the impact behaviour of materials under non-equilibrium process has been used. Physical research revealed that significant microstructural refinement of the alloy is observed after such type of loading, as the result of which the fine grains are formed with subgrain refinement which takes place within the basis of alloy.

Structural self-organization of titanium alloys under impulse force action

Abstract Based on the example of testing the two-phase high-strength titanium alloy VT22 and submicrocrystalline commercially pure titanium VT1-0 with different initial structures, the basic regularities are found in the variation of the mechanical properties under specific impact with oscillation loading on the elastic section of stress-strain curves. It is experimentally shown that for the two-phase high-strength titanium alloys, the addition of specific impact with oscillation loading on the elastic section of stress-strain curves can be used as a technological method for improving the initial mechanical properties, in particular, ductility.

Influence of Impact-Oscillatory Loading upon the Mechanical Properties of the VT-22 Titanium Alloy Sheet

This study shows the effect of the specific impact-oscillatory loading (Dynamical nonequilibrium process) on the VT-22 titanium α+β-type alloy mechanical properties and microstructure. Experiments were conducted using modified universal testing machine. Physical research revealed that significant microstructural refinement of the alloy is observed after such type of loading, as the result of which the fine grains are formed with subgrain refinement which takes place within the basis of alloy. It was found that overall plastic deformation of this alloy can be increased by a factor 2.75 compared with its initial state without significant loss of strength. Also we show that such process can be used as a preliminary microstructure refinement method for such alloy.

Influence of dynamic non-equilibrium processes on strength and plasticity of materials of transportation systems

New experimental results on the effect of additional force impulse loading on the variation of the initial structure of the aircraft material (alloys D16, 2024-T3, VT22) at various stages of deformation are presented and a significant enhancement of its initial plasticity is achieved. Complex investigations into the material properties after a dynamic non-equilibrium process made it possible to describe the main regularities in the nature of deformation and fracture of materials, which allowed proposing general recommendations on using the revealed physical and mechanical regularities in the evaluation of strength of aircraft structures.

Risks Associated with the Use of High-Strength Titanium Alloys in Transportation Systems

On an example of testing sheet high-strength (α + β) titanium alloys with different percentages of α and β phases, the danger of using titanium alloys with a large α phase content in transportation systems subjected to impact-oscillatory loading is shown. Under impact-oscillatory loading, dynamic nonequilibrium processes (DNP) with self-organization of the structure can be realized in titanium alloys. As a result, depending on the initial percentage of α and β phases in alloys, the impact-oscillatory loading can significantly affect fluctuations in the initial plastic deformation of the alloys upward or downward without appreciably reducing the strength of the alloy.