scholarly journals Production technology of prefabricated structures using fibre cement

2019 ◽  
Vol 6 (1) ◽  
Author(s):  
Nikolay Spiridonov ◽  
Azariy Lapidus
Keyword(s):  
Cross Section ◽  
Production Technology ◽  
Raw Materials ◽  
Compressive Force ◽  
High Mobility ◽  
High Strength ◽  
Polymer Fibers ◽  
Conventional Concrete ◽  
The Cross ◽  
New Generation

The article deals with the production technology of prefabricated structures using fiber cement. Studying the properties of these structures, the author points out that the use of fiber cement made of polymer fibers is advisable in the manufacturing process of prefabricated structures, as a result of their use increases crack resistance, impact strength, fracture toughness, wear resistance, frost resistance, cavitation resistance, and also decreases shrinkage and creep Also in the article noted that the use of fiber cement structures without reinforcement is possible, if their primary work is aimed at compression in the case of the location of the longitudinal compressive force within the cross-section of the element or if the longitudinal compressive force is located outside the cross-section of the element and the bend, but it should be borne in mind that their destruction should not create an immediate danger to such objects, the life and health of workers, it is also necessary to control the serviceability and safety of the equipment. The author comes to the conclusion that today there are a number of opportunities to create high-strength fibroblasts of new generation, using domestic raw materials. Modern effective types of fiber make it possible to simplify the process of its introduction and mixing in the concrete mix, as well as make it possible to use technological equipment that is used in the manufacture of conventional concrete. At the same time, it is possible to obtain and use fiber cement mixtures with high mobility.

scholarly journals Are We Able to Print Components as Strong as Injection Molded?—Comparing the Properties of 3D Printed and Injection Molded Components Made from ABS Thermoplastic

2021 ◽  
Vol 11 (15) ◽  
pp. 6946
Author(s):  
Bartłomiej Podsiadły ◽  
Andrzej Skalski ◽  
Wiktor Rozpiórski ◽  
Marcin Słoma
Keyword(s):  
Tensile Strength ◽  
Injection Molding ◽  
Mechanical Strength ◽  
Cross Section ◽  
Fused Deposition Modeling ◽  
High Strength ◽  
Large Cross Section ◽  
Fused Deposition ◽  
Injection Molded ◽  
The Cross

In this paper, we are focusing on comparing results obtained for polymer elements manufactured with injection molding and additive manufacturing techniques. The analysis was performed for fused deposition modeling (FDM) and single screw injection molding with regards to the standards used in thermoplastics processing technology. We argue that the cross-section structure of the sample obtained via FDM is the key factor in the fabrication of high-strength components and that the dimensions of the samples have a strong influence on the mechanical properties. Large cross-section samples, 4 × 10 mm2, with three perimeter layers and 50% infill, have lower mechanical strength than injection molded reference samples—less than 60% of the strength. However, if we reduce the cross-section dimensions down to 2 × 4 mm2, the samples will be more durable, reaching up to 110% of the tensile strength observed for the injection molded samples. In the case of large cross-section samples, strength increases with the number of contour layers, leading to an increase of up to 97% of the tensile strength value for 11 perimeter layer samples. The mechanical strength of the printed components can also be improved by using lower values of the thickness of the deposited layers.

Springback law of high-strength 21-6-9 stainless steel tube in numerical control bending under different process parameters

2015 ◽  
Vol 231 (10) ◽  
pp. 1783-1792 ◽  
Author(s):  
Jun Fang ◽  
Shiqiang Lu ◽  
Kelu Wang ◽  
Zhengjun Yao
Keyword(s):  
Stainless Steel ◽  
Friction Coefficient ◽  
Cross Section ◽  
Process Parameters ◽  
High Strength ◽  
Steel Tube ◽  
Numerical Control ◽  
Stainless Steel Tube ◽  
Outer Diameter ◽  
The Cross

In order to achieve the precision bending deformation, the effects of process parameters on springback behaviors should be clarified preliminarily. Taking the 21-6-9 high-strength stainless steel tube of 15.88 mm × 0.84 mm (outer diameter × wall thickness) as the objective, the multi-parameter sensitivity analysis and three-dimensional finite element numerical simulation are conducted to address the effects of process parameters on the springback behaviors in 21-6-9 high-strength stainless steel tube numerical control bending. The results show that (1) springback increases with the increasing of the clearance between tube and mandrel Cm, the friction coefficient between tube and mandrel fm, the friction coefficient between tube and bending die fb, or with the decreasing of the mandrel extension length e, while the springback first increases and then remains unchanged with the increasing of the clearance between tube and bending die Cb. (2) The sensitivity of springback radius to process parameters is larger than that of springback angle. And the sensitivity of springback to process parameters from high to low are e, Cb, Cm, fb and fm. (3) The variation rules of the cross section deformation after springback with different Cm, Cb, fm, fb and e are similar to that before springback. But under same process parameters, the relative difference of the most measurement section is more than 20% and some even more than 70% before and after springback, and a platform deforming characteristics of the cross section deformation is shown after springback.

scholarly journals Optimization of Geometrical Parameters of Hollow-core Slabs by Formwork-free Shaping for Construction in Seismic Areas

2020 ◽  
Vol 8 (6) ◽  
pp. 4973-4977
Keyword(s):  
Cross Section ◽  
High Strength ◽  
Geometrical Parameters ◽  
Hollow Core ◽  
Constructive Solution ◽  
Industrial Buildings ◽  
Operational Load ◽  
Wide Range ◽  
Hollow Core Slab ◽  
The Cross

The building norms and standards of Uzbekistan on the reinforced concrete structures do not regulate the design of hollow-core slabs of formwork-free shaping, reinforced with prestressed wire reinforcement. The manufacturing technology of such slabs allows creating a wide range of products that increase the possibility of their use in various structural systems in residential, civil and industrial buildings, but in non-seismic areas only. The aim of this work is to develop a constructive solution for the cross section of a prestressed hollow-core floor slab of bench formwork-free shaping, reinforced with high-strength wire reinforcement, in order to create a wide range of products intended for construction in seismic areas. To achieve the goal, the problem of determining the optimal combination of height and configuration parameters of the cross section of such a slab is solved, meeting the normalized operational requirements and limitations of earthquake-resistant building standards. The main variable parameters are the height and the void degree of the section, characterized by the size and shape of voids. In calculating the cross-section of a hollow-core slab when substantiating the theoretical basis for the calculation, the cross section is reduced to the equivalent I-section. As a result of research, a constructive solution was developed for the slab cross section of the maximum parameter values (the span, operational load) set by the customer. The parameters of the slab cross-section are: the height 190 mm, the hollowness 38%, the height of the upper thickened flange (compared with the height of the lower flange) of the given section is 0.27h, the height of the lower flange is 0.17h, the reduced (total) thickness of all ribs “b” is 0.32 of the width of the upper flange. The voids in the section along the height of the slab are arranged asymmetrically. A patent for a utility model has been received for the proposed constructive solution of the slab cross section.

Microsilica Concrete: A Technological Breakthrough Commercialized

1984 ◽  
Vol 42 ◽  
Author(s):  
Farrokh F. Radjy ◽  
Kjell E. Loeland
Keyword(s):  
Silica Fume ◽  
High Strength ◽  
Binder Phase ◽  
Conventional Concrete ◽  
Technological Breakthrough ◽  
Micropore Structure ◽  
High Durability ◽  
New Generation ◽  
Condensed Silica Fume ◽  
The U.S

AbstractWith the advent of microsilica concrete, a new generation of high to ultra high strength and high durability concretes have become commercially feasible and are now being specified and used internationally. Microsilica concrete is produced by incorporating microsilica (beneficiated condensed silica fume) additives in conventional concrete mixes, using conventional materials and equipment. Flowing microsilica concretes with strengths as high as 17000 psi have become field realizable, also benefiting by durability improvements expressible by factors, not percents.Properties of microsilica concrete are reviewed, and property improvements qualitatively linked to a much refined micropore structure of the binder phase.Some recent and rapidly developing field and laboratory experience both in the U.S. and overseas are presented.

Study on the Porosity in Al-Zn-Mg-Cu High Strength Alloy DC Ingot

2016 ◽  
Vol 879 ◽  
pp. 790-794 ◽  
Author(s):  
Hui Xue Jiang ◽  
Hiromi Nagaumi ◽  
Shi Jie Guo ◽  
Chun Zou
Keyword(s):  
Cooling Rate ◽  
Cross Section ◽  
High Strength ◽  
Direct Chill ◽  
Thickness Direction ◽  
X Ray ◽  
Density Method ◽  
Width Direction ◽  
Strength Alloy ◽  
The Cross

An Al-Zn-Mg-Cu high strength alloy ingot produced by Direct-Chill casting was used in this study. The distribution of porosity in the cross section of the DC ingot was investigated by the precision density method (Archimeds’ principle), also X-ray microtomography technique was used to quantitatively analyze porosities in typical positions. The pattern in the cross section as well as in the thickness and width direction was obtained. The results show that: in the cross section of the ingot, porosity was increasing gradually from the surface to the center of the ingot; porosity shows an overall escalating trend from the surface to the center of the ingot both in thickness direction and in width direction; porosity was closely related to the cooling rate in the ingot; oxide inclusions have an effect on the formation of porosity to some extent.

scholarly journals PRODUCTION TECHNOLOGY AND MECHANICAL PROPERTIES OF A NEW GRADE OF STEEL FOR FORGINGS WITH INCREASED STRENGTH AND IMPACT STRENGTH

2021 ◽  
Vol 72 (4) ◽  
pp. 15-21
Author(s):  
Marek Burdek ◽  
Jarosław Marcisz ◽  
Jerzy Stępień
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Impact Strength ◽  
Cross Section ◽  
Production Technology ◽  
Numerical Calculations ◽  
Steel Composition ◽  
The Cross ◽  
Increased Strength

The study involved the development of the basics of production technology and the testing of the mechanical properties of a new grade of steel for forgings with increased strength and impact strength, intended for special products. The scope of the tests includ-ed a proposal for a new steel composition along with the production of ingots and its further processing into forgings in industrial con-ditions, using an input with various dimensions of the cross-section, proposed as a result of numerical calculations, including the performance of heat treatment in two variants. As a result of tests and analyses, it was found that the proposed technology enables the production of semi-finished products with the assumed level of strength and impact strength.

scholarly journals Manufacturing of fiber-reinforced concrete bridge arches

2021 ◽  
Vol 48 (3) ◽  
pp. 99-105
Author(s):  
M. R. Nakhaev
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Bending Moment ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Concrete Bridge ◽  
Fiber Reinforced ◽  
Reinforced Concrete Bridge ◽  
The Cross ◽  
High Strength Fiber

Objective. A new method of manufacturing arches for a fiber-reinforced concrete bridge in the form of an analogue of permanent formwork is considered. Within the framework of this work, research results have been obtained that confirm the effectiveness of the system for the construction of bridge arches of various configurations.Method. The proposed developments will improve the strength characteristics of the bridge arch for small and medium bridges by optimizing the shape and size of the cross section in accordance with the change in the bending moment along the length of the arch. At the same time, reduce its metal consumption by several times.Result. The results obtained confirmed the effectiveness of electrostatic spraying of dry concrete mixture with simultaneous moisture up to moisture, which contributes to the work of capillary forces for compaction of concrete layers and the manufacture of a profiled strong shell (analogue of non-removable reinforced formwork) from reinforced fiber-reinforced concrete.Conclusion. By varying the shape and dimensions of the cross- section, the thickness of the shell and the degree of its reinforcement, as well as filling this shell with high-strength fiber-reinforced concrete, it is possible to design and manufacture bridge arches for various loads.

scholarly journals Research of physicomechanical and design characteristics of vibrated, centrifuged and vibro-centrifuged concretes

2021 ◽  
Vol 21 (1) ◽  
pp. 5-13
Author(s):  
L. R. Mailyan ◽  
S. A. Stel'makh ◽  
E. M. Shcherban ◽  
Yu. V. Zherebtsov ◽  
M. M. Al-Tulaikhi
Keyword(s):  
Axial Compression ◽  
Cross Section ◽  
Lightweight Concrete ◽  
Raw Materials ◽  
Control Sample ◽  
Standard Samples ◽  
Axial Tension ◽  
The Cross ◽  
Design Characteristics ◽  
Centripetal Forces

Introduction. Currently, the obtaining of lightweight concrete and reinforced concrete products and structures with the improved structure and characteristics is a challenge. This can be achieved through centrifugation or in a more advanced way — vibro-centrifugation. At the same time, the influence of centrifugal and centripetal forces of inertia in these types of technologies causes differences in the cross-section properties of concrete products and structures. To reflect this in the calculations, it is required to experimentally and analytically investigate the qualitative and quantitative patterns of such differences in the characteristics of concretes obtained through different technologies.Materials and Methods. The study used the cross-section averaged characteristics of concrete — “integral characteristics of concrete”. The applicable raw materials included portland cement 500, crushed stone fraction 5-20, medium sand. Nine control samples of annular cross-section obtained through vibrating, centrifuging, and vibro- centrifugation were manufactured and tested. The essence of the technique was that each manufactured experimental control sample was used in several types of tests in-parallel. From the total annular section of each sample, three conditional quadrants were distinguished, from which standard samples of small size were cut out. Subsequently, they were tested for axial compression, tension, and flexural tension. The following test equipment was used: electronically controlled mechanical press IPS-10 — for compression testing of prisms, and the breaking machine R-10 — for testing samples for axial tension. Strain sensors and dial indicators were used to measure concrete deformations. Oscilloscopes were also used to obtain the deformative and strength properties of concrete, including full deformation diagrams with descending branches.Results. We have analyzed the calculation results of the integral design characteristics of the concretes obtained through vibration, centrifugation and vibro-centrifugation. It is established that due to the influence of centrifugal and centripetal forces of inertia under centrifugation and vibration centrifugation, the characteristics of concrete in cross-section become different. In some cases, these differences can be very significant. We have developed and tested the following: a new method for evaluating the dependence of the integral (cross–section averaged) design characteristics of concrete (density, cubic and prismatic axial compressive strength); ultimate deformations under axial compression; axial tensile and flexural tensile strength; ultimate deformations under axial tension; elasticity modulus; diagram of “stress ϭb– strain εb” under compression; diagram of “stress ϭbt–strain εbt” under tension on the manufacturing technology (vibrating, centrifuging, vibration centrifugation).Discussion and Conclusions. Based on the results of the research, conclusions are formulated on the positive effect of the proposed technology of joint vibrating and centrifuging. It consists in improving the integral design characteristics and structure of concrete from vibrating to centrifuging and from centrifuging to vibro-centrifuging.

scholarly journals Characteristics of wool raw materials in the Southern Federal District

2020 ◽  
pp. 29-32
Author(s):  
Yu. A. Kolosov ◽  
V. V. Aboneev ◽  
A. M. Abdulmuslimov ◽  
A. S. Kiselev
Keyword(s):  
Cross Section ◽  
Raw Materials ◽  
Federal District ◽  
High Energy ◽  
International Standards ◽  
Climate Conditions ◽  
Merino Wool ◽  
The Cross ◽  
Strategic Program

Relevance. Sheep wool is one of the types of products that requires high energy costs of feed. Therefore, sheep breeding should be based in regions that allow for their soil and climate conditions to contain animals of this type with the lowest material costs. One of these regions of the Russian Federation is the southern Federal district. Assessment of the state of fine wool production in the region makes it possible to develop a science-based strategic program for managing this process, which can be universal and used in relation to other territories. This is the relevance of our research.Methods. Analytical, statistical, computational, and biometric research methods were used for their implementation.Results. As a result, it was found that there is currently a certain stagnation in the production of Merino wool in the Southern Federal District. Therefore, additional means of regional and federal support are needed to encourage producers to increase the number of sheep that produce uniform wool. Certification of wool based on methods consistent with international standards of the IWTO countries in this territory revealed a number of qualitative features of the raw materials produced. The largest share in the structure of produced wool — 79–93% — is occupied by raw materials with a diameter of the cross section of the fibers of 20.6–23.0 microns. Very insignificant is volume of wool diameter of the cross section of the fibers less than 20.5 microns — less than 1%. It is produced only in the Rostov region. It was also established that the share of wool with contamination by easily-and difficult-to-separate impurities at the level of 1.5–2% is from 38 to 100% of the produced wool in different regions of the district. The authors propose a system of complex selection and technological techniques to improve the quality of fine wool produced.

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