Analysis of the stressed-strained state of the foundation-shell at interaction with the elastic-plastic medium

On the basis of modern numerical implementations of the finite element method the article presents the justification of the adequacy of the method of solving the problems of structures straining in their contact interaction with the elastic-plastic nonlinear soil medium. Compatible calculations of structures and nonlinear bases, which are described by modern mechanical and soil models within one problem is a significant technical problem. The solution of the assigned tasks is possible only within the framework of numerical methods, the most common of which is the finite element method (FEM). The construction of the computational finite element model raises many complex questions that require additional detailed study. In addition, the compliance with the state building norms and regulations is an important factor for further practical use. The use of numerical methods in the calculation of machines and structures, taking into account their interaction with the elastic-plastic medium is largely determined by the complexity or even impossibility of analytical calculation due to the complexity of structural schemes, heterogeneity of material features, uneven soil layers, implementation of step-by-step work execution technologies and so on. The combination of the latest achievements in the field of structural mechanics and soil mechanics is a promising direction for the development of effective approaches to building discrete models of space systems “structure-nonlinear base” for solving applied problems. The use of the developed method allows to significantly specify the structures stress state interacting with the soil base, and to significantly specify the impact on the calculated level of the base bearing capacity. Only the simultaneous consideration of the nonlinear resistance of the soil base together with the plasticity and the structure destruction in the numerical simulation of the foundation-shell load provided good agreement with the natural experiment data as to the type of the boundary state and the bearing capacity level.

Another Side of Shellac

Shellac discs were quickly eclipsed by the new “Vinylite” LP records after the 1950s and, eventually, discontinued entirely. Yet the hyper-plastic medium lived on, generating a number of widespread and enduring resonances in twentieth-century affective and material cultures. This chapter is about these lives and afterlives of shellac, focusing especially on marginal and deregulated (but not necessarily demonetized) markets since 1950. This chapter argues that repurposing shellac records may ultimately be seen as an act of unlocking, transforming, and liquidating recorded sound. Shellac can thus be interpreted as an allegory of the passages between solid and liquid modernities, where modernity is understood in terms of ceaseless material renegotiations. The chapter explores two main perspectives on material reshapings of history, power, and cultural memory. To study waste and its infrastructures prompts us to examine process-based aspects of culture, considered as an intricate entwinement of natural, historical, geological times. In doing so we may also release “a vitality intrinsic to materiality.” Indeed, this chapter deploys infrastructural analysis “as a political, deconstructive gesture of investigation into the scars, textures, and structures of the contemporary as it dynamically incorporates the past (without ‘resolving’ it).”

MODELING THE PROCESS OF STRAIN AND MOTION OF THE SOIL IN A SUBSOILER OPERATION AREA

Analysis of available literature shows that nowadays an advanced scheme of the technological process and new designs of operating elements of the subsoiler working in conditions of deblocked cutting has been developed. The aim is to improve the quality and to reduce the energy consumption by machines and equipment during deep tillage. However, at present, the theory of vibrations and strength loading of the units of subsoiler, when its operating elements interact with soil, is not sufficiently developed. This paper highlights the issues regarding the modeling of soil during interaction with operating elements of a subsoiler. Based on the use of the Rakhmatulin model of a compressible plastic medium and the Ilyushin «flat cross-section hypotheses», the equation of the soil motion is formulated, and the dynamic phenomena occurring in the soil and subsoiler elements under variable traction are described. The calculation results are obtained in the Maple-8 programming environment using the methods of solid mechanics and soil mechanics.

Screen environment in the Moscow subway (metro)

The Moscow underground (Metro) today is showing active development: new series of trains appear; stations are being built. Apart from material-plastic medium, the screen, virtual reality also emerges. It plays the key role in establishing a new metro mythology. This paper attempts to trace new perspectives of the underground’s virtual life and the points of their interfacing with the objective, material environment. One can loosely specify three types of screen media in the Moscow Metro: information panels (located above the doors in cars), interactive structures (Info-SOS at stations and screens with sockets in “head” and “tail” parts of modern trains), “television” screens” (In the lobby and built-in between car`s door and window, where the Moscow metro lines were traditionally located, and small screens at the eye level of standing passengers). They have different semantic content and types of communication with passengers. There are a number of evident trends in providing video sequence on screens of the Moscow metro in the second half of 2019. The headings broadcast on the screens went sequentially, from more socially significant subjects to quizzes and announcements. The alternation of short stories gave the impression that it took less time to travel. The entire block of on-screen information worked on the effect of “accelerating” time, creating the illusion of greater rapidity of the subway. The Moscow metro today is not so much about the architectural environment but rather a virtual communicative one, which, in addition to entertaining, calming, distracting from problems and uplifting, also represents a function of animating the metro, informing it with a temperament and intonation component. In the process of immersion in a simulated media of the Moscow metro, one finds out that it turns to be a virtual organism with a complex system of “organs”, its own nervous system and its own needs. The first and foremost of which is to preserve, strengthen the love of their passengers, perhaps even make them addicted to the metro environment and inspire them for continuous improvement and modernization of the world.

A Dynamic expansion of a cylindrical cavity in a compressible elastic-plastic medium. The Analysis of medium resistance to dynamic penetration of a sharp-nosed impactor

This paper presents the solution of the problem related to the dynamic cylindrical cavity expansion in a compressible elastic-plastic medium. Finite strains, nonlinear compressibility and dependence of the yield stress versus pressure are taken into account in the problem formulation. The study targets at developing a new engineering model on the penetration of a sharp-nosed impactor in the range of middle impact velocities based on the problem analysis results of the cylindrical cavity expansion in a half-space (cylindrical cavity expansion approximation). Based on the analytical approach a model is obtained that determines the resistance of the medium to dynamic cavity expansion. The main parameters of the model depend on the mechanical properties of the medium. For these dependences we proposed approximating relations based on manipulation of the mechanical properties of a number of materials (some alloys and soils). To derive the dynamic penetration model the A.Ya. Sagomonyan assumption of the radial expansion of the hole is used. It is assumed that particles of the medium material move in a radial direction from the surface of the impactor penetrating into the shield. Such assumption can be applied for the class of impactors in the form of slender sharp-nosed bodies of revolution. Based on the assumptions we obtained a model of the medium resistance to the dynamic penetration of a slender sharp-nosed body of revolution. The new model, in addition to the "standard" strength and inertial components, contains the "attached mass", which changes during the penetration process. The experimental validation of the new penetration model using a series of experimental studies on the penetration of various forms of impactors into aluminum alloys is considered. The influence of the “attached mass” and inertial forces of the medium resistance to the penetration is estimated. The conditions of applicability of the new model are obtained: the penetration model is applicable for estimation of the resistance of a compressible medium to penetration of a thin sharp-nosed body of revolution at impact velocities of 200-800 m/s.

Relaxation model of dynamic deformation of elastic-plastic media

A variant is considered for the relaxation model of a loaded elastic-plastic medium with dislocation kinetics of plastic shearing. The model is formulated in rates and includes two independent strain rates: total strain rate, which corresponds to the rate of external action, and local rate of plastic response of the material, which represents the ability of the medium to generate strain-induced defects. This makes it possible to describe both local relaxation processes in the elastic-plastic medium and average relaxation of stresses in a loaded specimen. The model being developed amounts to microscopic ones. All model parameters are determined from independent experiments for the evolution of the dislocation continuum during loading of macroscopic specimens. The model provides an adequate description of the dynamic effects of the macroscopic response of materials depending on the strain rate: the upper and lower yield points (yield drop, yield plateau), subsequent strain hardening as well as features of cyclic and alternating loading, ideal and nonideal Bauschinger effect.

Three-Dimensional Analysis of a Landslide Process on a Slope in Carpathian Flysch

The paper presents a 3D (spatial) analysis of deformation processes in the landslide slope Bystrzyca in Szymbark near Gorlice (Low Beskid – Carpathians; N 49°37′ 09″, E 21°05′ 49″) carried out by the computer code FLAC3D based on the finite difference method. The numerical analysis was performed to determine the influence of the orientation of layers and discontinuities and of hydrogeological conditions on slope deformations and the failure mechanism during sliding processes. The massif is modeled as an elasto-plastic medium obeying the Coulomb-Mohr criterion. Two variants of hydrogeological conditions are analyzed, namely the “dry slope” (without water) and the “wet slope” (entirely saturated). The influence of the orientation of discontinuities (modeled as “ubiquitous”) on the landslide mechanism is investigated as well. Few orientations of discontinuities with respect to the dip direction of the slope surface are considered, namely consequent, insequent, and subsequent (two variants in each case). The results show a clear impact of the pattern of discontinuities and hydrogeological conditions on the deformational behavior of the landslide and the shape of the slip surface. The 3D approach and results of the numerical simulation of the landslide movement prove the necessity of 3D modeling in some cases.