Деформация тонких пленок полуметаллов методом купольного изгиба подложки

The results of a study of the semimetal films deformation produced by dome bending of the substrate are presented. Deformation control was carried out by means of X-ray diffraction analysis. It is shown that the dome bending method can be used to study films under planar deformation in a film-substrate system with different thermal expansion coefficients. The maximum in-plane deformation for bismuth films of 1 mkm thickness order was found. It was shown that the deformation created by the dome bending of the substrate in combination with the use of substrates with different temperature expansion makes it possible to obtain a relative in-plane deformation of bismuth films up to 0.8% at 300 K.

Блочные и монокристаллические пленки сплава висмут--сурьма 3-12 ат% с подслоем сурьмы

We investigated the effect of the antimony underlayer (10 nm) on the structure and galvanomagnetic properties of bismuth-antimony solid solution thin films (3-12 at.% Sb). The films were obtained on mica substrates by discrete vacuum evaporation and zone recrystallization. We found that the misorientation of the crystallite plane (111) increases relative to the film plane as well as the crystallite sizes decrease. The antimony underlayer does not change the crystallographic orientation during recrystallization and increases the film adhesion. The change in the galvanomagnetic coefficients when using a sublayer is due to the classical dimensional effect and increasing plane deformation.

Layer-dependent Fracture Strength of Few-layer WS2 Induced by Interlayer Sliding: A Molecular Dynamics Study

Understanding the relationship of interlayer interaction with mechanical properties and behaviors of two-dimensional layered materials (2DLMs) is critical in favoring the development of related nanodevices, nevertheless, still challenging due to the difficulties in experiments. In this work, nanoindentation simulations on few-layer WS2 were conducted by varying tip radius, suspended membrane radius and membrane size using molecular dynamics simulation. Consistent with our previous experimental results, few-layer WS2 exhibited layer-dependent reduction in fracture strength owing to the uneven stress distribution among individual layer induced by interlayer sliding under out-of-plane deformation. Besides, apparent curve hysteresis was observed due to interlayer sliding in the supported region when large tip radius and membrane radius were employed. However, instead of the supported part, the interlayer sliding within the suspended part resulted in the reduced fracture strength with the increase of layer number. These findings not only provide an in-depth comprehension on the influence of interlayer sliding on the fracture strength of few-layer WS2, but also suggest that the role of interlayer interaction should be seriously considered during nanodevice design.

Analysis of the structural behavior of a historical mosque damaged due to an earthquake: Sofular mosque example

Since the earliest period of history, many civilizations have ruled our country. Historical structures, which we inherited from these civilizations, should be transferred safely to future generations. For this purpose, it is essential to clearly determine the behavior of these historical structures. In the present study, one of these historical structures, Sofular mosque located in Merzifon, was examined in detail by static and dynamic analysis. In the analysis, the mechanical properties of the material obtained by experimental studies were used. In the static analysis, the mosque was analyzed under its own weight, and it was obtained that the stresses have large values at the supports of the main dome. So, it can be said that the dome has to be supported at these points. The results of the modal analysis show that the mosque has translational displacements with great mass ratios through two orthogonal directions. This shows that the mosque will have out of plane deformation during an earthquake. Also, under the dynamic effects of seismic forces, it was identified that critical out of plane deformations could occur at the upper parts of the eastern and western facades. Also, it is clear that large stress and deformation values could occur at the narthex part. Moreover, it is determined that the dome portion is involved in translational motion and can be damaged during an earthquake.

Mathematical Model of the Deaeration of Finely Dispersed Solid Media in a Spherical Matrix of a Roller-Type Apparatus

The additional operation of deaeration (compaction) of powders affects the quality of many products of chemical industries, the conditions for their delivery. Otherwise, energy consumption increases significantly. The aim of this work is the modeling of the deaeration of solid finely dispersed media in a gap with perforated hemispherical shapes on the surfaces of the shaft and conveyor belt within the framework of the mechanics of heterogeneous systems. A plane-deformation model is described, neglecting the forces of interphase interaction and taking into account the compressibility of a solid-particle-gas mixture without elastoplastic deformations. The model assumes consideration of the movement of (1) the components of the solid skeleton together with the carrying phase as a whole; (2) gas in an isothermal state through the pores of a finely dispersed material. This work is devoted to the study of part (a), i.e., behavior of the solid particle-gas system as a whole. The efficiency of the seal-deaerator is estimated using the obtained analytical dependencies for the main strength and speed indicators. The change in the degree of compaction of a spherical granule made of kaolin with given strength characteristics is investigated. It is shown that for the initial time interval up to 3.7⨯10−2 s, the growth of the porosity value relative to the horizontal coordinate along the conveyor belt is exponential and increases by a factor of 1.1. After eight such time intervals, the porosity values stabilize along the indicated coordinate with an increase of more than 1.4 times from the initial value.

Out-of-plane deformation reduction via inelastic hinges in fibrous metamaterials and simplified damage approach

The mechanical behavior of fibrous metamaterials is mainly determined by the interactions between the fibers composing the architecture. These interactions are usually of two different kinds: those directly depending on the positions of the fibers and those that need mediators, usually consisting of hinges, either inelastic or perfect, inducing restrictions on the kinematics of the fiber joints. In cases of interest, it has been observed that hinges can either have a certain torsional stiffness or behave as perfect joints, simply ensuring that the fibers remain interconnected, but not applying any constraint on the relative rotations between them. Here the effect of torsional stiffness of inelastic hinges is studied in two shear tests for a selected fibrous metamaterial. It is shown that the stiffness of hinges can be tailored to avoid, or at least reduce, out-of-plane deformations. Moreover, it is shown that, after reaching a threshold, permanent deformations are observed. This phenomenon is treated in a simplified way, by introducing damage in the continuum model.

Stress Analysis in Damaged Pipeline with Composite Coating

This paper studied the distribution of stresses near damage in the form of axial surface cracks in a pipeline reinforced with a spiral-wound composite coating. The authors applied the homogenization method to determine the effective elastic characteristics of a structurally anisotropic layered package. By means of the classical momentless theory of shells, it was established that the stress state of the coated intact pipe under the pressure of the pumped product depends on the parameters of the geometry of the capacity strip, as well as on the component composition of the heterogeneous coating. The finite element method was applied to solve the problem of plane deformation of a piecewise homogeneous ring with an internal crack perpendicular to the interface. This problem assumes the linearity of the materials and the ideal mechanical contact with the layers. The effect of the composite coating and the size of the damage on the magnitudes of the energy flow into the crack tip, and on the stress intensity factor, was studied in detail. Various variants of the coating were considered, namely, winding of the coating on an unloaded pipe and reinforcement of the pipe under repair pressure.

Intramolecular Charge Transfer of 1-Aminoanthraquinone and Ultrafast Solvation Dynamics of Dimethylsulfoxide

The intramolecular charge transfer (ICT) of 1-aminoanthraquinone (AAQ) in the excited state strongly depends on its solvent properties, and the twisted geometry of its amino group has been recommended for the twisted ICT (TICT) state by recent theoretical works. We report the transient Raman spectra of AAQ in a dimethylsulfoxide (DMSO) solution by femtosecond stimulated Raman spectroscopy to provide clear experimental evidence for the TICT state of AAQ. The ultrafast (~110 fs) TICT dynamics of AAQ were observed from the major vibrational modes of AAQ including the νC-N + δCH and νC=O modes. The coherent oscillations in the vibrational bands of AAQ strongly coupled to the nuclear coordinate for the TICT process have been observed, which showed its anharmonic coupling to the low frequency out of the plane deformation modes. The vibrational mode of solvent DMSO, νS=O showed a decrease in intensity, especially in the hydrogen-bonded species of DMSO, which clearly shows that the solvation dynamics of DMSO, including hydrogen bonding, are crucial to understanding the reaction dynamics of AAQ with the ultrafast structural changes accompanying the TICT.