Papers by Keyword: Load Capacity

Abstract: Background. Clinching is a conventional cold forming process in which two or more sheets can be joined without auxiliary parts. A pre-forming of the parts to be joined, which is introduced by previous manufacturing steps, has an influence on the joining result. When considering the suitability for joining with regard to the formability of the materials, the influence of the preforming steps must be taken into account. The influences of strain hardening and sheet thickness on the joining properties must be investigated. In this context, a Finite Element Method (FEM) based metamodel analysis of the clinching process was carried out in [1] to investigate the robustness of the clinching process with respect to the different material pre-strains. In [2], the method was extended to the load bearing simulation.Procedure. The metamodel from preliminary work based on various FE models, which predicts the load-bearing capacity of a clinched joint influenced by pre-straining, is compared here with experimental data and the accuracy of the metamodel prediction is discussed. For this purpose an experimental procedure was further develop which allows the preforming of metal sheets from which joining specimens can be separated with a certain degree of unidirectional deformation. In the study, the procedure for preparing the joint specimens and the results of the loading tests are presented. Different possible relevant pre-strain combinations are investigated and compared with the simulation results, to validate the FE models and choose suitable metamodel.

Abstract: Concrete filled steel tubes (CFST) represent a composite building member suitable especially for the construction of columns of a skeleton frame. Filling the steel tube with concrete allows the use of suitable properties of both materials and their interaction. This is very beneficial in a fire exposure, where a circular column has slightly better fire resistance than a square column. In case of an assessment of columns at the ultimate limit state (ULS), a buckling resistance decides. In previous research, it was found that increasing the strength of concrete increases buckling resistance only to a certain extent. The main aim of the article is to show through a theoretical study what benefit the use of ultra-high strength concrete has for buckling resistance of CFST.

Abstract: "Fiber Reinforced Polymers FRP" provide good alternatives to regular reinforcing steel, as their resistance to environmental factors specifies them and provide durability, in addition to their appropriate prices. These polymers are of various compositions and forms, some of which have a basic composition of glass fibers, others contain carbon or additional materials. They have used instead of steel reinforcement as the main longitudinal rebar, also as laminates that can be attached to the concrete surfaces for shear or flexural resistance. In this study, "Glass Fiber Reinforced Polymers GFRP" has tested for shear performance, where a practical program has applied. Three "simply supported beams" as control specimens have been prepared and tested, with the other nine beams with different combinations of reinforcement of steel and GFRP for flexure and shear resistance. Specimens have examined and the results have analyzed. The results showed that the use of GFRP as for main reinforcement with GFRP laminates instead of shear steel reinforcement increases the load capacity by 11%, also decreases the deflection by 46%.

Abstract: An ice crossing is a road constructed on an ice-covered river, organized in the absence of a bridge, as well as in view of the impossibility of a ferry crossing in winter due to the formation of ice cover on water bodies. For most of the regions of Russia, in the cold season, the establishment of negative temperatures is typical, as a result of which ice crossing is a common transport facility. So, in the country annually opens more than 500 crossings, about 20 of which are located in the Perm Krai. Their opening takes place in December - early January, and closing - in late March - early April. The easiest way to arrange crossings is on natural ice, as a result of which their carrying capacity increases as the natural thickness of the ice increases. Because of this, the passing of heavy vehicles is possible only in January – February, which is a significant drawback. Today, there are several ways to artificially increase the carrying capacity, which include reinforcing the ice sheet with geosynthetic material. This method is a new and rather promising direction in road construction due to the reusable use of geomeshs. The article discusses the dependence of changes in the characteristics of the ice cover on the applied geosynthetic material, as well as technological and economic comparison of reinforcement variants. To this end, materials were collected on organized crossings of the Perm Krai, possible types of geomeshs were examined, and calculations were carried out to determine the carrying capacity of the crossing. This reinforcement method contributes to the earlier passage of heavy vehicles at the crossing, and also improves the safety of traffic on it and prolongs its service life.

Abstract: The aerostatic journal bearings are widely used in ultra-precision machine tools. Due to remarkable ability of the porous medium in flow restriction, the porous aerostatic journal bearings are better than other types of aerostatic bearings in load carrying capacity, stiffness, damping and dynamic stability. The partially porous aerostatic journal bearing has the advantages of easy production and low cost. Moreover, the gap between the porous insert and the spindle can be adjusted to reduce the eccentricity due to high speed rotation. In this study, the effects of the size of the porous insert and the thickness of the air gap between the spindle and the housing on the gap pressure, the stiffness and the load carrying capability of the partially porous aerostatic journal bearing were figured out for performance evaluation.

Abstract: This article describes load capacity of dynamically loaded gears, more precisely describes the mechanical pulsation tests of carburized gears with different thickness of case-hardened depth and case-hardening technology, i.e. addition or removal of certain steps during the case-hardening process of the tooth flank and foot root. The comparison was made on six different process chemical-heat treatment, in two thicknesses of case-hardened depth and two pressure angles. Results are shown and compared in a Wöhler’s curve.

Abstract: This paper presents an analysis of porous layered long journal bearing lubricated with ferrofluid using displaced infinitely long wire magnetic field model. The ferrofluid flow in the porous region is analyzed using modified Brinkman model. Nondimensional pressure and shear stress expressions are derived using Reynolds boundary conditions. Nondimensional load capacity and coefficient of friction are evaluated under the influence of permeability of porous media, porous layer thickness, lubricant layer thickness, magnetic field intensity and distance ratio parameter. A porous layered journal bearing lubricated with ferrofluid increases the load carrying capacity and reduces the coefficient of friction.

Abstract: The article describes the version of safety fluid couplings where synchronization is ensured by using the lockup device with steel balls. The ways to increase the load capacity of the lockup device are considered. The mechanical behavior of the safety fluid coupling with the lockup device used for synchronizing has been parameterized in the course of experiments.

Abstract: Due to that the load capacity of the conventional herringbone-grooved cylindrical journal bearing (HGJB) decreases significantly with a decreasing dimension, a requirement exists for miniature HGJB with high load capacity in miniaturized spindle motor applications. This paper investigates the design and characterization of a novel HGJB using dual-layer herringbone-grooved patterns for small spindle motors and cooling fans. In contrast to conventional HGJBs, the proposed HGJB contains another set of herringbone-grooved pattern on its outer surface. The performance of the proposed HGJB is characterized numerically using flow field analysis software. Results show that compared to the conventional HGJB presented by the current group in a previous study, the proposed HGJB can improve the load capacity by 53.7% of the previous value.

Abstract: Crack is a common cause of the degradation of concrete and may affect its structural durability. In order to ensure the bridge is safe utilized in anticipated period of their future service, a proper maintenance process and procedure should be taken. Therefore in this study, static load test were performed on a pre-tensioned (PRT) concrete beam to investigate crack behaviour before and after retrofitting process as well as to determine the effectiveness of the retrofitting method. A control beam named PRTB1 will fully loaded until fail to determine its maximum load capacity and critical load of the beam. Hence another beam named PRTB-FRP will be loaded until it reached it critical load capacity before retrofitted using Fiber Reinforced Polymer (FRP) plates located beneath the centre of the beam. After the retrofitting process PRTB-FRP will be put again under the static load. The load capacity of PRTB-FRP increased compared to PRTB1 with some improvement in crack propagation behaviour after retrofitted.