Materials physics and mechanics

RAR RUS 101-107 K-4577-2013 57384230400 St.Petersburg State University Petrov Yuri y.v.petrov@spbu.ru

St.Petersburg, Russia

Saint Petersburg State University Selyutina Nina

St.Petersburg, Russia

Dynamic behaviour of concrete and mortar at high strain rates In this paper a uniform interpretation of the rate effects of fracture of the concrete and mortar is given on the basis of a structural-temporal approach based on the notion of incubation time. It is shown that temporal dependences of both materials are well calculated using the incubation time criterion. Different relation of ultimate stresses for concrete and mortar in quasi static and high rate loading conditions is observed. dynamic strength; incubation time of fracture; impact stress; strain rate; concrete; mortar https://mpm.spbstu.ru/article/2013.31.1/ MPM_2013_18_2_P01.pdf

RAR RUS 108-126 Alexandria University Ezzat

Alexandria, Egypt

Nizwa University El-Karamany

Oman

Arab Academy for Science and Technology El-Bary

Alexandria, Egypt

Alexandria University Fayik

Alexandria, Egypt

On fractional ultra-laser two-step thermoelasticity In this work, a new mathematical model of two-step heat conduction for an isotropic generalized thermoelasticity is derived using the methodology of fractional calculus. Some theorems of generalized thermoelasticity follow as limiting cases. An ultrafast fractional thermoelasticity model utilizing the modified fractional parabolic two-step heat conduction model and the generalized fractional thermoelastic theory was formulated to describe the thermoelastic behavior of a thin metal irradiated by a femtosecond laser pulse. The temporal profile of the ultrafast laser was regarded as being non-Gaussian. An analytical. numerical technique based on the Laplace transform was used to solve the governing equations and the time histories of the electron temperature, lattice temperature, displacement and stress in gold were analyzed. Some comparisons have been shown in figures to estimate the effects of the fractional order parameter on all the studied fields. The effect of α where (0 thermoelasticity; fractional calculus; femtosecond laser; modified two-step heat conduction; Laplace transforms; numerical results https://mpm.spbstu.ru/article/2013.31.2/ MPM_2013_18_2_P02.pdf

RAR RUS 131-134 Zhengzhou University Li

Zhengzhou, China

Zhengzhou University Xu

China

Zhengzhou University Tie

Zhengzhou, China

Simulation analysis of wind turbine blade during resin transfer molding process The wind turbine blade is a key component of wind turbine generator system, and helps capture wind energy effectively. The way of RTM resin transfer molding is generally used at home and abroad for blade manufacturing process. In order to ensure the quality of product, computer simulation analysis and experimental verification should be conducted before producing. Moldflow was used to simulate the process of wind turbine blade RTM. Based on that, variation diagrams about filling time, temperature, buckling deformation, pressure and so on are obtained. The results of analysis and comparison of with and without cooling, as well as optimize the defects existed indicate that cavitations concentrate in roots and edge of the blade, gas exhaust mold easily, there is no need to open up air vent additional; In filling stage, mold clamping force gradually increase slowly, in packing stage, mold clamping force sharply increase to reach peak, the mold clamping force disappears after packing; filling time with cooling process is longer than that without cooling process. It provides an important reference for wind turbine blade design and manufacture. wind turbine blade; RTM; simulation analysis https://mpm.spbstu.ru/article/2013.31.3/ MPM_2013_18_2_P03.pdf

RAR RUS 135-142 Ioffe Institute Vinogradova

St.Petersburg, Russia

ITMO University Nikulina

St.Petersburg, Russia

Ioffe Institute Mynbaev

St.Petersburg, Russia

ITMO University Kovsh

St.Petersburg, Russia

Peter the Great St. Petersburg Polytechnic University Odnoblyudov

St.Petersburg, Russia

Ioffe Institute Nikolaev

St.Petersburg, Russia

ITMO University V.E. Bougrov

St.Petersburg, Russia

Efficiency comparison of light emitting diodes based on monochromatic chips and chips with phosphor We have considered energy efficiency of two red-blue LED-based lighting systems prospective for use in horticulture. The first one used LED chips emitting at 455, 660 and 730 nm, and the second one was based on blue 455 nm chips and a red phosphor with peak emission wavelength of 670 nm. The research has shown that at equal emission proportions at the specified peak wavelengths, the chip solution was 5 % more energy.efficient at phosphor concentration of 1 %, and 8 % more efficient at 10 % of phosphor. LEDs greenhouse emitters; phosphors; energy efficiency https://mpm.spbstu.ru/article/2013.31.4/ MPM_2013_18_2_P04.pdf

RAR RUS 143-147 Ioffe Institute Vinogradova

St.Petersburg, Russia

ITMO University Nikulina

St.Petersburg, Russia

Optogan Group Braslavskii

St.Petersburg, Russia

Optogan Group Solovieva

St.Petersburg, Russia

Ioffe Institute Mynbaev

St.Petersburg, Russia

Ioffe Institute Nikolaev

St.Petersburg, Russia

F-1445-2014 7202768874 0000-0003-3738-408X ITMO University Romanov Alexey alexey.romanov@niuitmo.ru

St.Petersburg, Russia

ITMO University V.E. Bougrov

St.Petersburg, Russia

Temperature stability of colored LED elements Temperature stability of the optical power output of colored (blue-red) light emitting diode (LED) elements is considered. It is shown that LEDs based on blue 455 nm semiconductor chips have the best thermal stability, which is expressed in just 4 % of optical power losses with LED board temperature increasing from 25 °C up to 50 °C. The value of optical power losses for red chips emitting at 660 nm and 730 nm were 7 % and 11 %, respectively, while devices based on 455 nm blue chips and red nitride phosphors with 2 % and 8 % phosphor concentration showed losses of 4 % and 8 %, respectively. Wall plug efficiency of the studied samples demonstrated a similar trend with the temperature increasing as the optical power did. LEDs; temperature stability; greenhouse emitters; phosphors https://mpm.spbstu.ru/article/2013.31.5/ MPM_2013_18_2_P05.pdf

RAR RUS 148-155 Novokuznetsk Branch of the Kuzbass State Technical University Markidonov

Novokuznetsk, Russia

I.I. Polzunov Altai State Technical University Starostenkov

Barnaul, Russia

Durban University of Technology Tabakov

Durban, South Africa

Splitting vacancy voids in the grain boundary region by a post-cascade shock wave The structural transformation of vacancy voids in the grain boundary region of the bicrystal under the influence of post-cascade shock waves is studied with the aid of molecular dynamics simulations. It is shown that the void may be split into two parts or completely displaced. This effect depends on the relative position of the void and grain boundary dislocations. Also shown is a seamless transfer of vacancy clusters through the tilt grain boundary vacancy void; grain boundary; shock wave; method of molecular dynamics; computer simulation https://mpm.spbstu.ru/article/2013.31.6/ MPM_2013_18_2_P06.pdf

RAR RUS 156-170 Alexandria University Ezzat

Alexandria, Egypt

Alexandria University Youssef

Alexandria, Egypt

Generalized magneto-thermoelasticity for an infinite perfect conducting body with a cylindrical cavity A model of the equations of generalized magneto-thermoelasticity for a perfect conducting isotropic thermoelastic media developed in [1] is given. This model is applied to solve a problem of an infinite body with a cylindrical cavity is considered in the presence of an axial uniform magnetic field. The boundary of the cavity is subjected to a combination of thermal and mechanical shock acting for a finite period of time. The solution is obtained by a direct approach by using the thermoelastic potential function. Laplace transform techniques are used to derive the solution in the Laplace transform domain. The inversion process is carried out using a numerical method based on Fourier series expansions. Numerical computations for the temperature, the displacement and the stress distributions as well as for the induced magnetic and electric fields are carried out and represented graphically. Comparisons are made with the results predicted by the generalizations, Lord-Shulman theory, and Green-Lindsay theory as well as to the coupled theory. magneto-thermoelasticity; infinite perfect conducting body; cylindrical cavity https://mpm.spbstu.ru/article/2013.31.7/ MPM_2013_18_2_P07.pdf

RAR RUS 171-178 Ioffe Institute Shilyaev

St.Petersburg, Russia

Ioffe Institute Greshnov

St.Petersburg, Russia

Ioffe Institute Bazhenov

St.Petersburg, Russia

Ioffe Institute Mynbaev

St.Petersburg, Russia

Modeling recombination processes in solid solutions with large-scale composition fluctuations A model describing recombination processes in a solid solution containing large- scale compositional fluctuations is developed. Modeling considered carrier injection, their dynamics in a random potential, energy relaxation via phonon scattering, carrier capture by defects, and radiative and non-radiative recombination. The results of modeling show that intensive luminescence from the samples of solid solutions with large-scale compositional fluctuations, which is observed experimentally, is a substantial increase of carrier concentration in fluctuation-induced potential minima of the energy gap. a solid solution; recombination processes; modeling https://mpm.spbstu.ru/article/2013.31.8/ MPM_2013_18_2_P08.pdf