Bar Section Research Articles

Reduced Order Modeling and Parameter Identification of Induction Motors Based on FEA Solutions

Saturation and skin effects are two key factors which affect the simulation accuracy of three-phase induction motors. This paper introduces a methodology to decouple the rotor parameters to consider the saturation effect and skin effect independently. The skin-effect parameters are further modeled by a two-branch circuit with optimized sectioned-bar parameters. Then, a reduced order model (ROM) is developed based on the two-rotor-branch circuit to consider the skin effect in the time domain. All model parameters are identified by a two-stage algorithm based on FEA solutions in the frequency domain at various stator phase currents and rotor slips, using a locked rotor scheme with equivalent rotor conductivities. The first stage identifies both the decoupled saturation-effect parameters and skin-effect parameters, and the second stage identifies the two-rotor-branch parameters based on the optimal value of the rotor bar section ratio. The simulation results using the proposed model are compared with the transient FEA results and measured data.

Structural Analysis of Building with Diaphragm: A Review

The way of behaving of built up substantial second opposing casing structures in late tremors all around the world has featured the outcomes of lackluster showing of shaft segment joints.Huge measure of exploration completed to comprehend the mind boggling systems and safe way of behaving of bar section joints has gone into code proposals. The plan of built up substantial designs exclusively relies upon different boundaries like bowing second; shear power and stress prompted in a specific individual from a construction. Variety in the size of these boundaries might modify the whole plan of a specific component.In this paper we are introducing survey of writing connected with examination of designs considering stomach impact. Key Word: Slab, Review, Analysis, Structure, Forces, Stresses.

Development of Pure Torsion Test System for Micro Torsion Bars

MEMS scanners use micro torsion bars made of single crystal silicon. The push-in method is used to measure the mechanical properties of these micro torsion bars, in which a lever connected to the torsion bar is pushed. In the push-in method, the sliding force increases as the indentation amount increases, decreasing measurement accuracy. As a method to reduce the sliding force, we proposed to generate pure torsion in the torsion bar section by rotating a sample holder with a test sample attached. The proposed method can maintain the load detection axis of the load cell and the lever part at almost a right angle regardless of the degree of torsional angle, preventing slip at the contact point between the load cell and the lever part. The torsional spring constants of test samples were obtained and compared by three different methods: a testing system using this principle, a resonance frequency method, and a theoretical calculation. The accuracy of the developed testing system is -17.5 % to 12.7 % of the measurement error compared to the torsion beam spring constant obtained from the resonance frequency, and -15.6 % to 7.2 % compared to the theoretical calculation value, thus verifying the effectiveness of the proposed test method.

A study of the dependence of the 3-phase cage motor maximum torque on the centroid of the rotor bar section

The paper investigates the relative influence of the centroid of the three-phase squirrel cage induction motor rotor bar cross section, on the breakdown (maximum) torque of the machine. The influence of the angle of taper, the top width and the radial depth of the bar section, as established design variables, were also investigated so as to properly situate the degree of influence of the centroid, in comparison; as far as the maximum torque is concerned. The machines were investigated in their steady state operating mode using the equivalent circuit method. The machine learning capabilities of the Least Square Support Vector Machine (LSSVM) was deployed to extract by prediction, information about the likely dependencies between the randomized block of the geometric variables and the maximum torque, and the captured information was stored using the Root Mean Square Error (RMSE) of predictions. The validated results show that the rotor leakage reactance – a part determinant of the maximum torque; tends to show some significant sensitivity to a design change in the centroid of the transverse section of the rotor bar.

A study of the dependence of the 3-phase cage motor maximum torque on the centroid of the rotor bar section

A study of the dependence of the 3-phase cage motor maximum torque on the centroid of the rotor bar section

Comparative experiment of steel bar corrosion at concrete construction joints

Introduction: Construction joint is common and even inevitable in most of the reinforcement concrete structures. This study was to assess the effect of construction joints on chloride-induced corrosion of reinforcing steel in concrete.Methods: Test parameters included two environmental conditions (salt solution immersion condition and cyclic wet-dry condition), two forms of construction joint (direct wet joint and roughened wet joint) and four types of steel bar (mild steel bar, ferritic stainless-steel bar, austenitic-ferritic stainless-steel bar and epoxy-coated steel bar). The corrosion test of 90 specimens was carried out by electrochemical accelerated corrosion method. The weight loss of each steel bar and steel bar section in specimens was measured. An influence coefficient (k_j) of construction joint on local weigh loss of steel bars was defined.Results: Except for epoxy-coated steel bars, the most severe corrosion of experimental steel bars in concrete specimens all occurred at the joints, while the corrosion in non-joint sections of steel bars was relatively uniform and less. The weight loss rate of specimens has the range of 1.18% to 15.73% with an average value of 6.22%. The average k_j of mild steel bars, S11203 stainless steel bars, and S23043 stainless steel bars are 1.38, 1.92, and 1.97, respectively. The average k_j of specimens in immersion condition and cyclic wet-dry condition are 1.44 and 2.07. The corrosion of epoxy-coated steel bars mainly occurred at the damage locations of epoxy coating, not mainly at the joints.Conclusion: Chloride-induced corrosion of steel bars at construction joints was always more severe than at non-joints, especially in cyclic wet-dry environments, even for stainless-steel bar, but epoxy-coated steel bars were excluded.

Seismic Modelling of Corroded Reinforced Concrete Columns

Deterioration of seismic resistance of columns due to existing corrosion damage is investigated using advanced non-linear finite element simulation and analysis of a large database of tests with the objective to develop performance criteria for seismic evaluation and assessment. Current guidelines for structural seismic evaluation do not address how to account for the condition of the reinforcement. Incorporating the degree of bar corrosion in the evaluation procedures would complicate significantly the problem of seismic assessment. However, bar section loss, embrittlement, loss of material strength and interfacial bond, all affect the member’s residual mechanical properties, the hierarchy of failure modes and the consequences on seismic performance of complete structural components. In this work, simple modifications of existing nonlinear assessment procedures are proposed, in order to account for the effects of corrosion on seismic performance. Reduction factors of reinforcement stress–strain properties and column stiffness, strength and deformation capacity were calibrated to an assembled database of experimentally tested corroded columns, and were verified through advanced nonlinear finite element analysis, after modeling the effect of mass loss on material properties.

Study of the Vibrations of Some Composite Bars with Polypropylene Honeycomb Core and Carbon Fiber and Fiberglass Fabric Faces

The paper generalizes the Timoshenko model for thick bars, using a new model that is applied to the vibration study of multilayer composite bars. In the proposed mathematical model, three coefficients are introduced that take into account the non-uniformities of the tangential and normal stresses in the bar section. The vibrations of some composite bars with a polypropylene honeycomb core with a thickness of 10 mm, 15 mm and 20 mm are experimentally studied, on the faces of which one or two layers of carbon fiber, respectively glass fiber was poured. For each analysed bar, the stiffness and the equivalent modulus of elasticity are determined and the variation of the damping coefficient according to the length of the bar is studied.

Optical fiber measurement of local strains in a ribbed bar

AbstractRibbed bars are known for their enhanced bond to concrete. Their ribs make bar section variable along the axis and the strain profile is variable as well, under any given applied force. Such variable strain profile has not been measured so far, thus the stress profile and its effect on the global behavior of the bar cannot be determined. Though optical fibers are an effective means to measure the strains in structural members, their application to the study of bond behavior is still in its infancy. Such an application is the objective of this research project. Specially manufactured partly smooth and partly ribbed bars with optical fibers were tested in pure tension (bare bars) and in the pullout from concrete to investigate the strain profile variability. In the bare bars, the strain measured in the smooth part was constant (as expected), while in the ribbed part higher strains were measured but no localized effects were detected, and the location of the ribs was not identified. Similar behavior was obtained by 3D finite‐element analysis, which merely yielded slight ups and downs at ribs' locations, with an average strain that is similar to the measured strain. However, in the pull‐out tests, the strains were constant in the unbonded smooth part and exhibited an undulating profile in the bonded ribbed part, where the peaks were related to the locations of the ribs. Such promising results motivate further studies to improve the resolution of the proposed technique.

A New Form of Beauty: Irish Postpunk and the Liberalization of Ireland, 1977–1991

A New Form of Beauty: Irish Postpunk and the Liberalization of Ireland, 1977–1991 Kenneth L. Shonk (bio) the dark space festival was held on February 16–17, 1979, at the Project Arts Centre in the Temple Bar section of central Dublin.1 The multimedia event featured film, artwork, a striptease act, and live performances from a number of musical groups that eschewed tropes of rock and punk in favor of a new sound and aesthetic.2 The festival was to be headlined by John Lydon’s post–Sex Pistols group PiL (Public Image Limited) and English avant-garde troupe Throbbing Gristle. For reasons unknown the featured acts never made it to Ireland for the event. Nonetheless, Irish bands were able to fill in for the missing headliners, and those that did perform included the Virgin Prunes, the Modern Heirs, Berlin, the Atrix, Phantom Orchestra, Rocky de Valera and the Gravediggers, U2, and the New Versions.3 Noted British DJ John Peel was in attendance, and his presence—according to Irish Times journalist Joe Breen—may have “prompted the energetic performances [of the bands] and it is reasonable to assume he was [End Page 81] accordingly impressed.”4 Days before the event, festival organizer and center director Jim Sheridan said, “We think of it as a lovely hippy concept. . . . We think it’s gonna be total bleedin’ anarchy.”5 The event also included food. Tickets for the festival were £6—later reduced to £4 after the headliners dropped out— and could be purchased at various sites in Dublin, including upscale Grafton Street retailer Brown Thomas. Film, art, and food aside, the significance of this festival lay in the coalescing of groups central to a burgeoning Irish postpunk scene, where bands played a style of music that was a “particular kind of art rock” performed by “bohemian non-conformists” who wrote songs that “grappled with classic existentialist quandaries: the struggle and agony of having a ‘self’; love versus isolation; the absurdity of existence; the human capacity for perversity and spite; the perennial ‘suicide, why the hell not?’”6 More than a collection of transgressive and loud “new wave,” the Dark Space Festival was a moment of anarchic liberalization of Ireland—an early marker of a willingness by some in Ireland to shrug off the nation’s “culture of containment.” The Dark Space Festival marked a key watershed in not only the history of Irish popular music but also in Ireland’s social and cultural liberalization. That a youthful musical avant-garde was on display for a mere £4 speaks to an emergent and accessible space for a new musical aesthetic. The moment was not finite, however, as some of the bands that played the Dark Space Festival were featured in A Sense of Ireland, a government-sponsored showcase of Irishness where the cutting edge was situated alongside traditional arts. In short order, this localized music scene was elevated to a position where transgressive youth were part of the outward-facing Irish visage, marking a structural acceptance and promotion of countercultural alterity. The existence of an Irish variant of postpunk parallel to “scenes” in England and the United States presents an opportunity to examine a cultural moment when Irish musicians offered an explicit and thoughtful reaction to contemporary Ireland. The aesthetic of these bands—such as those featured at the Dark Space Festival and in A Sense of Ireland—conveyed a visual and aural transgression that was intent on identifying and rejecting the conservative elements [End Page 82] of Ireland’s culture of containment, in turn marking a particular moment in our growing understanding of Ireland’s transformation from “one of the most conservative places in Europe” to its “more socially liberal” status.7 The Dark Space Festival—and Irish postpunk writ large—shares some lineage with other Irish cultural watersheds, for it existed because of intrinsic and extrinsic forces rooted in Ireland’s history. Societal and demographic shifts in the 1960s and 1970s helped foster and define the Irish postpunk moment, and its form and function were undoubtedly Irish but not beholden to traditional Gaelic cultural tropes: there were little to no flourishes of Celtic themes or instrumentation, nor were there...

Behavior comparison of seven-types of steel–concrete composite stub columns under axial compression

Steel-concrete composite columns are widely used in civil engineering structures for superior structural performance and economical cost. In response to the varying construction conditions, extensive types of composite columns have been developed nowadays, including concrete-filled steel tubes (CFST), CFST with steel bar (CFST-B) or steel section embedded (CFST-S), steel tubed concrete (T-C), steel tubed reinforced concrete (T-RC), steel tubed steel-reinforced concrete (T-SRC), and the newly proposed steel-tube-confined CFST (T-CFST), etc. A systematic and comparative experimental study was conducted for the seven types of steel–concrete composite stub columns with the same steel ratio, aiming to clarify their differences and facilitate an appropriate selection. Experimental results showed that all the conventional composite columns suffered from brittle failure, which was changed to ductile failure for T-CFST. Moreover, the employment of internal rebar or structural steel led to a variation of 13.3% in the ultimate load of CFST members; setting steel gap at the column ends for T-C columns increased the ultimate load by about 10% further; the addition of outer steel tube and sandwich material in T-CFST achieved up to 42.4% higher ultimate load. The enhanced mechanical properties of T-C and T-CFST were resulted from the increasing concrete confinement by the outer steel tube. The current design codes for different types of composite columns were examined by the experimental results, and a more suitable design method is needed for T-CFST.

Comparison of Stress Fields near Longitudinal Construction Joints of Tied and Doweled Sections in Portland Cement Concrete Pavements

In Portland cement concrete (PCC) pavements, tie bars are commonly used at longitudinal construction joints (LCJs) to prevent the lanes from separating. Meanwhile, the increase in multiple lanes due to greater traffic volumes has raised concerns about potential longitudinal cracking; this has led to the use of dowel bars instead of tie bars at LCJs. However, there is a paucity of studies focused on the comparison between the behaviors of concrete pavement based on the restrained conditions provided by tie and dowel bars at LCJs. In this study, we investigated the effects of the placement of tie and dowel bars at LCJs on the potential for longitudinal cracking in response to the increase in concrete stress that may occur when the lanes are tied together in PCC pavements. Field testing verified that the variation in concrete strain was more restrained in the case of a tie bar than a dowel bar, whereas it resulted in higher stress in the concrete element in the tie bar section. However, the use of dowel bars caused more movement in the transverse direction at LCJs as compared with tie bars. Thus, our results indicate that using dowel bars reduces the potential for longitudinal cracking; however, it may increase the potential for lane separation.

Study of Temperature Field Inhomogeneities in Parallel Wire Strand Sections under ISO834 Fire

An accurate prediction of temperatures of parallel wire strands is essential to determine the fire-induced mechanical responses of cable-supported bridges. In this paper, the theoretical formula applicable to the temperature field calculation of parallel wire strand sections is established based on the basic theory of heat transfer, and its accuracy is verified. An equivalent steel round bar numerical model of the parallel wire strand is established, and the temperature history of the parallel wire strand section under ISO834 fire is analyzed using the theoretical formula and the equivalent steel round bar numerical model. The results show that the heating law of each layer steel wires of the parallel wire strand section is basically the same and all have a tendency to approach the fire source temperature with the increase of fire time. Due to the existence of thermal resistance, large temperature gradients occur in the parallel wire strand sections. The temperature field of the parallel wire strand section shows more significant inhomogeneous distribution than that of its equivalent steel round bar section due to the influence of the cavities. It indicates that the traditional equivalent steel round bar model does not genuinely reflect the inhomogeneous temperature rising characteristics of the parallel wire strand section. The temperature of the surface layer steel wires of the parallel wire strand section and its equivalent steel round bar section is very close. In contrast, the temperature difference of the inner steel wires is significant, i.e., the parallel wire strand section has a larger temperature gradient than its equivalent steel round bar section.

Formation of a Gradient Structure in Austenitic Stainless Steel AISI 321 by Radial-Shear Rolling

One of ways to increase the strength of a structural material is to grind its microstructure to an ultra-fine-grained state. But with the simultaneous increase in strength properties in ultrafine materials, there is an inevitable decrease in its plastic properties. The use of metal materials with a gradient structure is an effective way to solve the problem of increasing the plasticity of metal products in general. This work is devoted to the study of the possibility of a gradient structure forming in austenitic stainless steel AISI-321 using radial-shear rolling. The results of the studies showed that the UFG-structure extends in the bar from its surface to a depth of at least a quarter of the radius of the bar. The transition zone is in the region between 0.5 R and 0.25 R of the bar section. Anything deeper is rolling texture. Due to the structural heterogeneity of the cross-section of the bar, there is a smooth drop in the micro-hardness of the central zone of the bar by 10.2 %. All this testifies to the gradient character of the structure formed in bars of AISI-321 steel deformed on the radial-shear rolling mill.

Considering Grid Division Optimization of Free-Form Surface Roof Structure

The free-form surface roof structure is widely used in large-span public buildings due to its beautiful shape. Its grid division form is diverse, and the size and shape of the structural grid directly affect its bearing performance. In this paper, the grid optimization research is carried out for the free-form surface single-layer reticulated shell roof, based on the Rhino platform and the grasshopper module for parametric modeling. The karamba plug-in is used for structural analysis, and the roof structure of different grid divisions under various load conditions is analyzed, computing its response and its carrying capacity. Genetic algorithm is used to optimize free-form surface roof structure, with grid density, member bar length and section size as parameters. Comprehensive consideration of structural self-weight and maximum displacement and other design goals are considered. It provides reference for the design of free-form roof structure.

Experimental and numerical investigation on ultimate strength of four-legged latticed columns

Latticed built-up columns are applied more extensively than solid columns in structural engineering because of their excellent load-carrying capacity and light weight. Studies on the bearing capacity of latticed columns, particularly multiple-legged latticed columns, need to be conducted in detail. In this investigation, seven four-legged latticed column specimens of different bar sections, bar distributions and loading eccentricities under compressive loads were subjected to experimental tests. The initial geometric imperfections of the legs and bars were measured and introduced into the FE numerical method. The experimental results were then compared with those of Geometrical and Material Non-Linear Analysis with Imperfection in ABAQUS software. The combined data indicate that the bar section, bar distribution and loading eccentricity significantly influenced the ultimate strength of four-legged latticed columns, producing maximum variations of 105.67%, 65.7% and 48.48%, respectively. This investigation demonstrates the influence of lacing bars and improves the results obtained from FE numerical analytical techniques.

Realization of the innovative potential of radial-shear rolling for forming the structure and mechanical properties of AISI-321 austenitic stainless steel

In this paper the grain structure and mechanical properties of AISI-321 austenitic stainless steel subjected to 7 passes of radial-shear rolling at 1000 °С were investigated. The tensile strength (1076 MPa) and Vickers microhardness (322 HV) after 7 passes increased by 2.2 times and 2 times, respectively, relative to the initial annealed state (480 MPa, 160 HV). Ultra-fine grained structure (200-700 nm) formed in the bar section area from its surface to a depth of 0.25 of the radius. The transition zone is located in the area between 0.5 R and 0.25 R of the bar section. Anything deeper is a rolling texture. The 7-pass radial-shear rolling process is an effective way to form UFG structure and improved mechanical properties in AISI-321 austenitic stainless steel. Keywords: severe plastic deformation, ultra-fine grained structure, radial-shear rolling, microstructure, mechanical properties.

Sports bars: environmental design, drinking, and sports betting

Background Informed by literature on venue design and ‘nudging’ in the context of choice architecture, the purpose of this article is to investigate the physical design of, and practices enacted within, sports bars to provide some indication as to whether these venues are spaces that encourage risky drinking and betting. Methods Our analysis draws on three arms of data collection: (i) website review of licensed venues in Victoria, Australia that promoted sports telecasting; (ii) observational data collection including site visits to 50 venues in Victoria that promoted sport telecasting, and more intensive sessions of observation during six sporting matches; and (iii) in situ interviews with 200 sports bar patrons. Findings We identified three types of sports bars: (i) prototypical sports bars; (ii) venues that have a sports bar section; and (iii) venues that televise sport on occasion. Sports bar attendees reported moderately heavy drinking at sports bars and frequent engagement in sports betting. We identified two distinct groups of sports bettors. Prototypical sports bars and venues that televise sport on occasion attracted younger men who bet the least frequently but in the highest amounts, while venues that have a sports bar section attracted older men who bet more often but in smaller amounts. Conclusions We identified several design elements across the three types of venues, each ‘nudging’ sports betting and drinking in different ways. Any focused public health work in relation to sports bars will need to consider the social and physical design elements of different sports betting environments.

Changes in the vertical distribution of hyporheic and benthic fauna associated with low flow conditions in the headwaters of the Tafna river (northwest Algeria)

This study investigated temporal changes in the vertical distribution of invertebrates during periods of low flows in the Tafna wadi, a semi-arid Mediterranean river characterised by a general decline in average flows. The hyporheos was sampled along a 130-m stretch at depths of 0.3, 0.6 and 1 m in a pool-riffle sequence and a lateral gravel bar. Benthic fauna was collected on each sampling occasion from different locations in the studied sections. Sampling was conducted in two consecutive years (2014 and 2015) at the end of the spring (high waters) and over a 2-month period during the low summer flow. The results indicated that high surface water temperatures may initiate the movement of some taxa into the interstitial habitat, thus supporting the hyporheic refuge hypothesis. In the hyporheic zone, the low oxygen rates recorded deeper in the sediment and in the last low-flow months caused significant declines in taxonomic richness, and lower pH values resulted in a reduction in invertebrate abundances. In the benthic zone, high flow velocities increased richness but decreased invertebrate abundances. A large number of taxa were found in the gravel bar section reflecting the more suitable living conditions in this habitat compared with the river reach (high DO rates).

Effect of Residual Stresses on the Fatigue Behaviour of Torsion Bars

This article deals with the effect of residual stresses on the fatigue behaviour of torsion bars exposed to cyclic torsional loading with different effective loading ratios, R. The residual compressive stresses on the surface were induced during technological processes by cold surface rolling and torsional overloading (presetting) into the plastic region due to the increase in the elastic linear range for torque. In the paper, we consider two different technological processes for introducing compressive residual stress on the surface of same material. We analysed the stress states affected by different residual and applied stress using the Drucker-Prager criterion in order to determine the actual stress state. Results show that the fatigue limit can be achieved if the maximum principal stresses (combined from residual and applied stresses) do not overcome the safe stress zone. As soon as the maximum principal stress reaches the edge of the safe zone, the number of cycles to failure rapidly reduces. Experimental results show that the effective loading ratio Reff, and consequently the stress amplitude, varies through the cross section of the bar. This initiates the fatigue crack under the surface, in the highest amplitude stress zone, independent of the effective loading ratio Reff. Consequently, increasing the compressive residual stresses on the surface by a second technological process has no significant effect on fatigue crack initiation in situ far from the surface. Increasing the plastic torsional prestress can shift the maximum stress amplitude far from the surface, but a significant volume of material should remain elastically loaded in order to ensure balance with compressive stresses from the surface of the solid bar section.