scholarly journals The current state and tendencies of using rheological models for self-forming wooden structures

2020 ◽  
pp. 112-122
Author(s):  
V. S Ponomarev ◽  
G. G Kashevarova
Keyword(s):  
Rheological Model ◽  
Experimental Studies ◽  
The Self ◽  
Building Structures ◽  
Forming Process ◽  
Rheological Models ◽  
Factors Affecting ◽  
Wooden Structure ◽  
Shrinkage And Swelling ◽  
Wooden Structures

Wood is a natural and ecological material. Exceptional mechanical properties of wood allow it to be used in building structures subject to chemically active substances. However some changes in mechanical characteristics of wood under the influence of water and temperature, as well as its anisotropy, limit the application areas of this material. Based on the results of the research by S.P. Timoshenko, foreign scientists proposed a method that makes it possible to use these shortcomings of wood to create wooden structures of unique shapes. This article considers the self-forming process of glued layered wooden structures, which is based on various rheological processes taking place in wood. In order to predict the shape of a glued layered wooden structure obtained with the self-forming method, an accurate rheological model is required, which takes into account all wood deformation mechanisms. We analyzed the available rheological models of wood proposed or described both by Russian and foreign scientists, as well as the international experimental studies and numerical modeling results of the self-formed glued layered wooden structures. Based on the analysis results, it was found that the present rheological models do not take into account a number of factors that influence the process of self-forming of glued layered wooden structures. The rheological model, which includes a complete list of factors affecting wood deformation (elastic and plastic deformation, wood shrinkage or swelling, viscous-elastic creep deformation and mechanical and sorption deformation), is the most promising for creating unique architectural objects from glued wood. But it also has a number of shortcomings, mainly due to inconsideration of some factors and few experimental studies. Such factors include the geometric parameters of layers of the glued wooden structures, the surface treatment of layers, temperature, as well as wood species. These factors influence the process of wood shrinkage and swelling, thus the final shape of a wooden structure. It is necessary to have additional experimental and theoretical studies of the mechanical behavior of glued wooden structures which will take into account these factors, as well as to study other species of wood including their combinations.

scholarly journals ANALYSIS OF RHEOLOGICAL MODELS OF PROCESS OF SELF-FORMING OF GLUED WOODEN

2020 ◽  
Vol 16 (2) ◽  
pp. 94-100
Author(s):  
Vladislav Ponomarev ◽  
Galina Kashevarova
Keyword(s):  
Plastic Deformation ◽  
Numerical Modeling ◽  
Moisture Content ◽  
Rheological Model ◽  
Experimental Studies ◽  
Rheological Models ◽  
Model Experiments ◽  
Promising Technology ◽  
Expansion Coefficients ◽  
Elastic And Plastic Deformation

The article considers a promising technology for self-shaping glued wooden elements of curved forms. This method is based on rheological processes occurring in wood, such as dehumidification and swelling of wood and its anisotropic properties. To predict the final curved shape of the wooden structure, the authors analyzed existing rheological models of wood and concluded that the rheological model proposed by European researchers includes the most complete list of factors that affect the process of deformation of wood: elastic and plastic deformation, drying and swelling of wood, deformation of viscous-elastic creep and mechanical sorption deformation. Based on the results of experimental studies and numerical modeling of the change in the curvature of glued wooden elements, which were made by European researchers, it was found that the proposed rheological model of wood needs to be clarified, namely, the correction of hygro-expansion coefficients depending on the moisture content of wood. A further direction of the authors’ research will be aimed at conducting model experiments to determine the hygro-expansion coefficients of different grades of wood depending on the thickness of the wooden elements and the orientation of the layers in the glued structure.

scholarly journals Influence of vibration impacts from vehicles on the state of the foundation structure of a residential building

2019 ◽  
Vol 135 ◽  
pp. 03053
Author(s):  
Tatiana Zolina ◽  
Natalya Kupchikova
Keyword(s):  
Seismic Waves ◽  
Soil Layer ◽  
Experimental Studies ◽  
Residential Building ◽  
Structural Type ◽  
The State ◽  
Building Structures ◽  
Factors Affecting ◽  
Building Foundation ◽  
Foundation Structure

In this work, experimental studies were conducted on the effect of vibrational influences from highways on the state of the foundation structures of a five-story residential building in Astrakhan. The studies were combined with an examination of the geo-base, foundations, and foundation of a multi-story brick residential building. Studies have shown that over four years, damaged building structures underwent significant changes due to increased vibration from the highway, and the rate of deformation in the supporting structures prove their emergency state. It is confirmed that the main factors affecting the magnitude of vibration acceleration of the building foundation structure are: structural type of the building; distance from the building to the source of seismic waves; longitudinal wave propagation velocity in the soil layer.

DIESEL ENGINE OPERATION IN USE OF FUEL WITH ADDITIVES

2018 ◽  
pp. 18-24
Author(s):  
Petar Kazakov ◽  
Atanas Iliev ◽  
Emil Marinov
Keyword(s):  
Diesel Engine ◽  
Fuel Consumption ◽  
Diesel Fuel ◽  
Internal Combustion Engines ◽  
Experimental Studies ◽  
Combustion Engines ◽  
Engine Operation ◽  
Factors Affecting ◽  
Operating Modes ◽  
Positive Effects

Over the decades, more attention has been paid to emissions from the means of transport and the use of different fuels and combustion fuels for the operation of internal combustion engines than on fuel consumption. This, in turn, enables research into products that are said to reduce fuel consumption. The report summarizes four studies of fuel-related innovation products. The studies covered by this report are conducted with diesel fuel and usually contain diesel fuel and three additives for it. Manufacturers of additives are based on already existing studies showing a 10-30% reduction in fuel consumption. Comparative experimental studies related to the use of commercially available diesel fuel with and without the use of additives have been performed in laboratory conditions. The studies were carried out on a stationary diesel engine СМД-17КН equipped with brake КИ1368В. Repeated results were recorded, but they did not confirm the significant positive effect of additives on specific fuel consumption. In some cases, the factors affecting errors in this type of research on the effectiveness of fuel additives for commercial purposes are considered. The reasons for the positive effects of such use of additives in certain engine operating modes are also clarified.

Assessment of the volume activity of α-radioactive wastes on surface and specific contamination by portable γ-spectrometry method

2020 ◽  
pp. 468-473
Author(s):  
I. P. Korenkov ◽  
A. I. Ermakov ◽  
A. B. Mayzik ◽  
T. N. Laschenova ◽  
V. N. Klochkov ◽  
...  
Keyword(s):  
Specific Activity ◽  
Experimental Studies ◽  
Germanium Detector ◽  
Low Energy ◽  
Gamma Ray Spectrometry ◽  
Building Structures ◽  
Germanium Detectors ◽  
Volume Activity ◽  
Β Decay ◽  
Γ Spectrometry

The aim of the study is to evaluate the volume activity of radioactive waste (RW) by surface and specific alpha contamination using portable gamma-spectrometry.Materials and methods. Methods of rapid assessment of the content of α-emitting radionuclides in solid waste of various morphologies using gamma-spectrometers based on germanium detectors are considered. Computational methods for determining the effectiveness of radionuclide registration are presented.Results. The possibility of using portable gamma-ray spectrometry to assess the surface and specific activity of various materials contaminated with α-emitters (232Th, 235U, 238U, 237Np, 239Pu, 240Pu and 241Am) is shown. The calculated values of the registration efficiency of low-energy gamma-emitters obtained by modeling the spatial-energy parameters of the detector are given.To simplify the solution of this problem, the calculation program used 20 standard templates of various geometries (rectangular, cylindrical, conical, spherical, etc.). The main sources of error in the survey of contaminated surfaces, largesized equipment and building structures were investigated.Conclusions. The possibilities of portable γ-spectrometry for estimating the volume of RW based on the surface density of contamination of materials with radionuclides of uranium and transuranic elements are investigated. When using γ-spectrometer with a high-purity germanium detector with a range of γ-quanta extended in the low-energy region, radionuclides such as 232Th, 235U,238U, 237Np, 241Am were determined by their own radiation or by the radiation of their daughter products.The “problem” element is plutonium, for rapid evaluation of which it is proposed, in accordance with the radionuclide vector methodology, to use 241Am, which accumulates during the β-decay of 241Pu.According to calculations, the most likely value of the activity ratio 239Pu/241Am for the object where the work was performed (scaling factor) varies in the range from 5.0 to 9.0.Based on the results of calculations and experimental studies, the parameters of the efficiency of registration of various α-emitting radionuclides by portable γ-spectrometers. It has been found that for germanium detectors with an absolute efficiency of registering a point source of 7÷15%, it is n×10–5÷n×10–4%.

ADOLESCENTS IN CRIMINAL STREET GROUPINGS: REASONS AND MOTIVATIONS

2019 ◽  
Vol 29 (2) ◽  
pp. 195-199
Author(s):  
E.O. Chernova
Keyword(s):  
At Risk ◽  
Preventive Measures ◽  
Experimental Studies ◽  
Motivational Factors ◽  
Social Motives ◽  
Factors Affecting ◽  
Social Communities ◽  
Criminal Groups

The article gives an analysis of the results of authorial experimental studies. Motivational factors affecting adolescents' participation in criminal groups are considered, they are: dominant groups of motives, the predominance of aspiration to success or avoidance of failures. Thus, the author explores the subjective potential of the personality of adolescent groupers. According to the results of the research, the author concludes that the specificity of the motivation of such adolescents consists in the predominance of material motives, social motives (involvement in social communities, groupings) and motives of recognition and respect. The author notes that the motivation for avoiding failures is more characteristic of such adolescents than the motivation for the pursuit of success. It is concluded that the data obtained can serve as a basis for developing preventive measures when working with adolescents at risk.

The methodology of experimental research of the feed components extrusion process in order to improve its energy performance

2020 ◽  
pp. 147-152
Author(s):  
E. M. Ratnikov ◽  
D. O. Milko
Keyword(s):  
Experimental Studies ◽  
Energy Performance ◽  
Extrusion Process ◽  
Mathematical Methods ◽  
Screw Extruder ◽  
Mathematical Planning ◽  
Factors Affecting ◽  
Extrusion Processing ◽  
Definition Of

Annotation Purpose. Development of a program and methods for conducting experimental studies of the extrusion process with the definition of parameters and modes of operation of the extruder to improve its energy performance. Methods. Methods of mathematical statistics, synthesis, analysis, description and modeling were used. Results. The application of mathematical methods, in particular mathematical planning, reduces the number of experiments several times, and allows to evaluate the role of influencing factors, obtain a mathematical model of the process and determine the optimal conditions for its parameters and modes, etc. Conclusions. The methodology for experimental studies of a screw extruder is presented with the necessary equipment and methodology for processing the obtained experimental data. A mathematical method of planning, which reduces the number of experiments several times, allows us to evaluate the role of factors affecting productivity and energy intensity is presented. Keywords: extruder, auger, nutrients, research methodology, extrusion, processing, feed.

Evaporative self-assembly of binary mixture of soft colloids

2021 ◽  
Author(s):  
Merin Jose ◽  
Muraleedharapai Mayarani ◽  
Madivala G Basavaraj ◽  
Dillip Kumar Satapathy
Keyword(s):  
Binary Mixture ◽  
Self Assembly ◽  
Sessile Drop ◽  
Experimental Studies ◽  
The Self ◽  
Soft Colloids

We report experimental studies on the self-assembly and degree of ordering of binary mixture of soft colloids in the monolayer deposits obtained by controlled evaporation. A sessile drop containing soft...

Erosion Experiment of Self-Excited Oscillation Pulsed Jet

2014 ◽  
Vol 937 ◽  
pp. 614-619
Author(s):  
Chuan Lin Tang ◽  
Jie Pei ◽  
Dong Hu ◽  
Xiao Ting He
Keyword(s):  
Significant Influence ◽  
Cavity Length ◽  
Experimental Studies ◽  
The Self ◽  
Erosion Depth ◽  
Pulsed Jet ◽  
Excited Oscillation ◽  
Erosion Effect ◽  
Erosion Volume ◽  
Peak Value

In order to improve the erosion effect of jet under submergence condition, experimental studies of erosion generated from the self-excited pulsed jet was carried out by using developed self-excited oscillation nozzle. The erosion volume and depth of pulsed jet were measured and taking mortar block as an erosion part. The results were that the standoff has significant influence on erosion effect. The erosion volume firstly decreases with increases in cavity length and then increases to a peak value. Erosion volume of pulsed jet is significantly higher than that of continuous jet, the erosion depth of two jet has slight difference.

scholarly journals Formability study and metallurgical properties analysis of FSWed AA 6061 blank by the SPIF process

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Payam Tayebi ◽  
Ali Fazli ◽  
Parviz Asadi ◽  
Mahdi Soltanpour
Keyword(s):  
Base Metal ◽  
Strain Distribution ◽  
Thickness Distribution ◽  
Experimental Studies ◽  
Welding Process ◽  
Forming Limit ◽  
Forming Process ◽  
Friction Stir ◽  
Numerical Process ◽  
Tailor Welded Blank

AbstractIn this study, in order to obtain the maximum possible formability in tailor-welded blank AA6061 sheets connected by the friction stir welding (FSW) procedure, the incremental sheet forming process has been utilized. The results are presented both numerically and experimentally. To obtain the forming limit angle, the base and FSWed sheets were formed in different angles with conical geometry, and ultimately, the forming limit angle for the base metal and FSWed sheet is estimated to be 60° and 57.5°, respectively. To explore the effects of welding and forming procedures on AA6061 sheets, experimental studies such as mechanical properties, microstructure and fracture analysis are carried out on the samples. Also, the thickness distribution of the samples is studied to investigate the effect of the welding process on the thickness distribution. Then, the numerical process was simulated by the ABAQUS commercial software to study the causes of the FSWed samples failure through analyzing the thickness distribution parameter, and major and minor strains and the strain distribution. Causes of failure in FSWed samples include increased minor strain, strain distribution and thickness distribution in welded areas, especially in the proximity of the base metal area.

scholarly journals The use of classical methods and neural networks in deformation studies of hydrotechnical objects

2020 ◽  
Vol 12 (1) ◽  
pp. 718-725
Author(s):  
Maria Mrówczyńska ◽  
Jacek Sztubecki ◽  
Małgorzata Sztubecka ◽  
Izabela Skrzypczak
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Cylinder Surface ◽  
Building Structures ◽  
Steel Cylinder ◽  
Factors Affecting ◽  
Initial Stage ◽  
Artificial Neural ◽  
Set Of Points

Abstract Objects’ measurements often boil down to the determination of changes due to external factors affecting on their structure. The estimation of changes in a tested object, in addition to proper measuring equipment, requires the use of appropriate measuring methods and experimental data result processing methods. This study presents a statement of results of geometrical measurements of a steel cylinder that constitutes the main structural component of the historical weir Czersko Polskie in Bydgoszcz. In the initial stage, the estimation of reliable changes taking place in the cylinder structure involved the selection of measuring points essential for mapping its geometry. Due to the continuous operation of the weir, the points covered only about one-third of the cylinder area. The set of points allowed us to determine the position of the cylinder axis as well as skews and deformations of the cylinder surface. In the next stage, the use of methods based on artificial neural networks allowed us to predict the changes in the tested object. Artificial neural networks have proved to be useful in determining displacements of building structures, particularly hydro-technical objects. The above-mentioned methods supplement classical measurements that create the opportunity for carrying out additional analyses of changes in a spatial position of such structures. The purpose of the tests is to confirm the suitability of artificial neural networks for predicting displacements of building structures, particularly hydro-technical objects.

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