Создание и тестирование системы имитационного моделирования механических испытаний в режиме сверхпластичности с помощью специальной программы нагружения.
Computer simulation of mechanical testing is used primarily for the correct interpretation of their results and is particularly relevant in cases, when the properties of the material during deformation are essentially nonlinear. For example: when we study mechanical properties of materials with high rate sensitivity. First of all it is superplastic titanium alloys. Superplastic materials exhibit the ability to severe plastic deformation without discontinuities if forming occurs in a narrow range of strain rates, specific to each alloy and temperature-dependent. In the study of superplastic materials, it’s necessary to maintain a constant rate of deformation of the sample. This is achieved by conducting an experiment with a special program loading, crosshead speed at which change during the experiment.
The methods of biomechanical systems design with artificial elements are analyzed. The data of high-precision measurements of all set of the biometric characteristics, determining of biomechanical system is a basis of mathematical model. The calculations allows to predict complications at denture installation.
The influence of neutron irradiation on the mechanical properties of vanadium and the alloys V-10.6 Ti and V-10 Ti-6 Cr-0.05 Zr is investigated. Alloy samples are irradiated in the pile of a BOR-60 reactor to a fluence of (0.8-1)·10 22 cm -2 (E > 0.1 MeV) at 350°C. The results show that the irradiation of vanadium and its alloys in these conditions leads to insignificant (less than 0.1%) swelling but changes their mechanical properties (strength and plasticity). The radiational strengthening is greatest for pure vanadium and least for the alloy V-10.6 Ti. Adding chromium to the alloy reduces the positive effect of titanium and leads to low-temperature radiational embrittlement in the range 20-100°C. As shown by electron-microscope investigation, the change in mechanical properties of the alloys after irradiation is associated with the formation of a dislocational structure and with radiation-stimulated segregation.
This paper presents the research of the flow characteristics of the Ti-6V-4Al alloy in wide ranges of temperature (725 ‑ 950 °C) and strain rate (10-5 ‑ 10-2 s-1). The material processing maps were constructed based on the basis of dynamic materials model (DMM) developed by Prassad and modified by Narayana Murty. For the construction of such maps the data of the material’s flow stress at different temperatures and strain rates is necessary. To obtain such data the stepped tensile tests which allow get the stress - strain rate dependence at a given temperature are ideal. The experiments conducted consist of the tensile-testing of samples’ series at various temperatures with stepped change of the deformation speed. By the results of these tests the constitutive equations, which describe relationship between stress and strain rate for each temperature were obtained. The data was analyzed in terms of the two different approaches proposed by Prassad and Narayana Murty to assess the impact of deformation conditions on the formability and flow stability of the material. Based on these approaches, the processing maps which allow identifying the conditions of the Ti-6V-4Al alloy superplasticity were constructed.
This aim of this paper is the interpretation of the results of mechanical testing of materials to determine their properties under hot deformation. As an example, a simulation of rod stretching in superplasticity mode was considered. Comparing obtained data with the analytical solution was conducted.
This issue is the collection of the papers based on the talks presented at the extended workshop “Methods of simulations on supercomputers”, which was held at 21–3 April 2014, in Tarusa hotel Interkosmos of the RAS Space Research Institute. It is the workshop in the series of extended workshops, devoted to the computer technologies in natural sciences. Eighth workshop, as a current one, named “Methods of simulations on supercomputers”. The name is connected with the fact that workshops are supported within the research program the grant by Russian Scientific Foundation 14-21-00158 «Algorithms and methods for mathematical simulations on supercomputing systems, including hybrid ones». Important highlight of the workshop is the active participation of the young scientists, and more than half of the talks were done by the young speakers.
In this volume we have collected papers based on the presentations given at the International Conference on Computer Simulations in Physics and beyond (CSP2015), held in Moscow, September 6-10, 2015. We hope that this volume will be helpful and scientifically interesting for readers.
The Conference was organized for the first time with the common efforts of the Moscow Institute for Electronics and Mathematics (MIEM) of the National Research University Higher School of Economics, the Landau Institute for Theoretical Physics, and the Science Center in Chernogolovka. The name of the Conference emphasizes the multidisciplinary nature of computational physics. Its methods are applied to the broad range of current research in science and society. The choice of venue was motivated by the multidisciplinary character of the MIEM. It is a former independent university, which has recently become the part of the National Research University Higher School of Economics.
The purpose of this study is to find out the characteristics of hot forming of Ti-6Al-4V titanium alloy in order to determine the conditions of its superplastic behavior. The experiments were performed in two stages: the stepped tensile-tests series (temperature range 700 – 925 °С) and the constant strain rate tensile-test series (temperature range 775 – 925 °С). By the results of stepped tensile tests the constitutive equations which describe relationship between stress and strain rate for each temperature were constructed. On the base of obtained data, the temperature and strain-rate ranges which ensure the realization of superplasticity at forming of Ti-6Al-4V alloy as well as optimal strain rates which corresponds to the maximum value of strain rate sensitivity exponent were determined. In was shown that at low temperatures (700 – 775C) the Ti-6Al-4V alloy shows all signs of superplasticity, however at these temperatures the optimal strain rates are too slow for industrial technological procedures. The dependence between optimum strain rate and reciprocal temperature appears to be well fitted by exponential low. At the second stage of the experimental research, the tensile-tests with a constant, optimum for each temperature strain-rate were carried in order, to estimate the real initial flow stress and the character of strain hardening of the material during the deformation with optimum strain rate. In was found that flow stress values obtained by stepped tensile tests matches the values form constant-strain-rate tests with effective strain value equal to 0,2 and the strain hardening during the deformation with optimal strain rates is significant.